Optometry Notes

OPTOMETRY · SEMESTER 1 Blood Human Anatomy and Physiology START READING NOTES Contents of This Topic Overview Blood Composition Cells of the body are serviced by 2 fluids Blood The haematocrit Components of Blood Blood Plasma Plasma Constituents Formed Elements of Blood Erythrocytes (RBC) Erythrocytes Concentration of RBC in Blood Erythropoeisis Substances Required for Synthesis of RBC Genesis of RBC Myeloid stem cells give rise to RBCs, platelets, and all WBCs except for lymphocytes. Regulation of RBC Production Hemopoietic Growth Factors Role of erythropoeitin Regulation of Erythropoiesis Feedback Control of RBC Production Medical Uses of Growth Factors Formation of Haemoglobin Formation of haemoglobin Haemoglobin Iron Metabolism Transport of Iron Absorption of Iron Daily Loss of Iron Destruction of RBC Anaemia Blood Loss Anaema Aplastic anaemia Megaloblastic anaemia Haemolytic anaemia THE BLOOD Overview Blood Composition and functions Red blood cells: -Characteristics & functions, formation and destruction White blood cells: -Characteristics, functions, formation Platelets : -Haemostasis, fibrinolysis Blood groups and transfusion problems Blood Composition Blood Is an opaque, red liquid Consisting of several types of cells suspended in a complex, amber fluid Plasma Composed of Cells Plasma, liquid in which the cells are suspended The cells (formed elements) include Erythrocytes (RBCs) Leukocytes (WBCs) Platelets (cell fragments) The branch of science concerned with the study of blood, blood-forming tissues, and the disorders associated with them is called Hematology. Cells of the body are serviced by 2 fluids blood composed of plasma and a variety of cells transports nutrients and wastes interstitial fluid bathes the cells of the body Nutrients and oxygen diffuse from the blood into the interstitial fluid and then into the cells Wastes move in the reverse direction. Blood Its pH is 7.4 (7.35-7.45) 99% of the cells are RBC which are the O2 carrying cells of blood Blood is thicker (more viscous) than water and flows more slowly than water Average blood volume = 8% of body weight = 5.6L (70*0.08) On the average 60% of blood vol = plasma ( 3 liters) 40% of blood vol = RBC (2 liters) Values vary considerably in different people depending on sex and other factors The haematocrit Defined as the % of total blood that is erythocytes It is determined by centrifuging a sample of blood in a haematocrit tube Erythrocytes are forced to the bottom Plasma remains at the top Leucocyte and platelets form a thin layer in between Blood Plasma = 55% Leukocytes and platelets (buffy coat) RBC = 45% (Hct = 45%) Components of Blood Hematocrit 55% plasma 45% cells 99% RBCs < 1% WBCs and platelets Blood Plasma Non-cellular part of blood 0ver 90% water 7% plasma proteins created in liver confined to bloodstream albumin maintain blood osmotic pressure globulins (immunoglobulins) antibodies bind to foreignsubstances called antigens form antigen-antibody complexes fibrinogen for clotting 2% other substances electrolytes, nutrients, hormones, gases, waste products Plasma Constituents Constituent Functions 1 Water =92% of plasma wt Medium for carrying all other constituents 2 Electrolytes (inorganic) Total < 1% plasma wt Keep water in ECF, act as buffers, for blood clotting, for excitability of cells 3 Proteins 7% of plasma wt.= 7.3 g/100 ml Albumin, globulin, fibrinogen Provide non penetrating solute of plasma, Act as buffers, transport protein,clotting factors, enzymes, antibodies Blood Plasma Constituents Constituent Functions 4 Gases CO2, O2 CO2 is waste product, O2, for oxidative metabolism, 5 Nutrients Glucose, amino acids, lipids and cholesterol, vitamins, trace elements Nutrition Blood Plasma Constituents Constituent Functions 6 Waste products: urea, creatinine, uric acid, bilirubin 7 Individual hormnes Metabolic, Control system Blood Formed Elements of Blood Red blood cells ( erythrocytes ) White blood cells ( leukocytes ) Granular leukocytes neutrophils, eosinophils, basophils Agranular leukocytes lymphocytes = T cells, B cells, and natural killer cells monocytes Platelets (special cell fragments) Erythrocytes (RBC) Blood Erythrocytes Functions of RBC To transport Haemoglobin Hb carries O2 Hb carries O2 form lungs to tissue In lower animals Hb circulates as free protein in plasma In human being when it is free 3% leaks from capillaries Into tissue spaces; glomerular filtrate Erythrocytes Blood Hence for Hb to remain in blood stream It must exist inside the RBC Other functions of RBC include; Buffer function Contain carbonic Anhydrase which catalyze H2o + Co2 H2co3 Hco3- + H+ -Thus transport CO2 from tissues to lungs in the form of HCO3- Hb is an excellent acid/base buffer -Thus RBC are responsible for most buffering capacity of the blood Erythrocytes Blood Shape and size of RBC Biconcave discs Diameter = 7.8 µm Thickness at the thickest point = 2.5 µm average volume = 90 – 95 µ3 The shape of the RBC can change remarkably It is a bag which can be deformed To any shape; This allows it to pass through capillaries without problem Normal RBC Has great excess cell membrane for quantity inside Hence deformation does not stretch the membrane to cause it to rapture Concentration of RBC in Blood Blood In normal men average number of RBC Is 5,200,000 (+/- 300,000) per cubic ml In women average number of RBC Is 4,700,000 (+/- 300,000) Quantity of Hb in RBC When Hb formation is deficient in bone marrow % Of Hb in RBC may fall and volume of RBC may decrease Concentration of RBC in Blood Blood When Haematocrit = 40 – 45% Quantity of Hb in each cell is normal Whole blood of men contain 16 gm Hb/dl Whole blood of women contain 14 gm Hb/dl Each gram of pure Hb Combine with 1.39 ml of O2 Hence in normal man total amount carried Is = 1.39 * 16 = 21 ml of O2 per dl of blood In normal woman Is = 1.39 * 14 = 19 ml of O2 per dl of blood RBC have the ability to conc HB up to 34 g/dl Erythropoeisis Blood Sites of RBC production include York sack During early weeks of embryonic life Liver, spleen, lymph nodes Middle trimester Bone marrow Last trimester, after birth Bone marrow of all bones Up to

OPTOMETRY · SEMESTER 1 Body Fluids Human Anatomy and Physiology START READING NOTES Contents of This Topic BODY FLUIDS COMPARTMENT INTRODUCTION INTRODUCTION CONT … Body Water Content BODY FLUIDS Total Body Water Fluid Compartments Intracellular Fluid Compartment (ICF) FLUID COMPARTMENTS Fluid Compartments in the Human Body Intracellular Fluid Intracellular Fluid CONT … Extracellular Fluid Extracellular Fluid CONT … Extra Cellular Fluid Compartment (ECF) Blood Volume Composition of Body Fluids Composition of Body Fluids CONT … The Concentrations of Different Elements in Key Bodily Fluids PART II Fluid Movement between Compartments Fluid Movement between Compartments CONT … Capillary Exchange Capillary Exchange CONT … Exchange Between Plasma and ISF Exchange Between ECF and ICF PART III Solute Movement between Compartments Solute Movement between Compartments CONT … Facilitated Diffusion OF GLUCOSE Water Balance Water Balance CONT … Regulation of Water Intake Regulation of Water Intake CONT … Regulation of Water Output Regulation of Water Output CONT … Role of ADH Role of ADH CONT … Aquaporins diuretic ANY QUESTIONS? BODY FLUIDS COMPARTMENT BODY FLUIDS 1 INTRODUCTION Homeostasis, or the maintenance of constant conditions in the body, is a fundamental property of all living things. In the human body, the substances that participate in chemical reactions must remain within narrows ranges of concentration. Too much or too little of a single substance can disrupt your bodily functions. BODY FLUIDS 2 INTRODUCTION CONT … Because metabolism relies on reactions that are all interconnected, any disruption might affect multiple organs or even organ systems. Water is the most ubiquitous substance in the chemical reactions of life. The interactions of various aqueous solutions—solutions in which water is the solvent—are continuously monitored and adjusted by a large suite of interconnected feedback systems in your body. Understanding the ways in which the body maintains these critical balances is key to understanding good health. BODY FLUIDS 3 INTRODUCTION CONT … The chemical reactions of life take place in aqueous solutions. The dissolved substances in a solution are called solutes. In the human body, solutes vary in different parts of the body, but may include proteins—including those that transport lipids, carbohydrates, and, very importantly, electrolytes. Often in medicine, a mineral dissociated from a salt that carries an electrical charge (an ion) is called an electrolyte. For instance, sodium ions (Na+) and chloride ions (Cl-) are often referred to as electrolytes. BODY FLUIDS 4 INTRODUCTION CONT … In the body, water moves through semi-permeable membranes of cells and from one compartment of the body to another by a process called osmosis. Osmosis is basically the diffusion of water from regions of higher concentration of water to regions of lower concentration of water, along an osmotic gradient across a semi-permeable membrane. As a result, water will move into and out of cells and tissues, depending on the relative concentrations of the water and solutes found there. An appropriate balance of solutes inside and outside of cells must be maintained to ensure normal function. BODY FLUIDS 5 Body Water Content Human beings are mostly water, ranging from about 75 percent of body mass in infants to about 60 percent in adults, to as low as 45 percent in old age. The percent of body water changes with development, because the proportions of the body given over to each organ and to muscles, fat, bone, and other tissues change from infancy to adulthood. Your brain and kidneys have the highest proportions of water, which composes 80–85 percent of their masses. In contrast, teeth have the lowest proportion of water, at 8–10 percent. BODY FLUIDS 6 BODY FLUIDS 7 Total Body Water In normal adult human 70 kg Total body water = 60% of body weight = 42 liters (70*0.6) However, % can change depending on Age, sex, degree of obesity An increase in age is accompanied by increase in fat Hence % of body wt that is water decreases By age of 60 TBW = 50% of body wt in men BODY FLUIDS 8 Total Body Water Women have more fat Contain less water than men Total body water is 45 – 50% of body wt Children Neonate contain more water than adults (75 – 80% TBWt) By about 1 yr body water = 60% of body wt BODY FLUIDS 9 Fluid Compartments Intracellular Fluid Volume = 28 L, 2/3 TBW Interstitial Fluid Volume = 10.5 L, 75% of ECF Plasma Vol = 3.5 L, 25% of ECF BODY FLUIDS ICF (2/3 TBW) ECF (1/3 TBW) Total Body Water (TBW) 42 L, 60% of Body Wt 10 Intracellular Fluid Compartment (ICF) About 28 liters of the 42 liters are inside body cells ICF constitutes 40% of total body weight (for 70kg), or 2/3 of total body water (60% of body water) BODY FLUIDS 11 FLUID COMPARTMENTS EXTRACELLUAR FLUID INTRACELLULAR FLUID INTERSTITIAL FLUID PLASMA TRANSCELLULAR FLUID CSF Intra ocular Pleural Peritoneal Synovial Digestive Secretions BODY FLUIDS 12 Fluid Compartments Body fluids can be discussed in terms of their specific fluid compartment, a location that is largely separate from another compartment by some form of a physical barrier. The intracellular fluid (ICF) compartment is the system that includes all fluid enclosed in cells by their plasma membranes. Extracellular fluid (ECF) surrounds all cells in the body. Extracellular fluid has two primary constituents: the fluid component of the blood (called plasma) and the interstitial fluid (IF) that surrounds all cells not in the blood. BODY FLUIDS 13 FLUID COMPARTMENTS BODY FLUIDS 14 Fluid Compartments in the Human Body The intracellular fluid (ICF) is the fluid within cells. The interstitial fluid (IF) is part of the extracellular fluid (ECF) between the cells. Blood plasma is the second part of the ECF. Materials travel between cells and the plasma in capillaries through the IF. BODY FLUIDS 15 Intracellular Fluid The ICF lies within cells and is the principal component of the cytosol/cytoplasm. The ICF makes up about 60 percent of the total water in the human body, and in an average-size adult male, the ICF accounts for about 25

OPTOMETRY · SEMESTER 1 Physiology Of Digestive System Human Anatomy and Physiology START READING NOTES Contents of This Topic LEARNING OUTCOMES INTRODUCTION FUNCTIONAL ANATOMY OF DIGESTIVE SYSTEM FUNCTIONAL ANATOMY OF DIGESTIVE SYSTEM CONT … WALL OF DIGESTIVE SYSTEM WALL OF DIGESTIVE SYSTEM CONT .. FOOD INTAKE REGULATION FUNCTIONS OF DIGESTIVE SYSTEM FUNCTIONS OF DIGESTIVE SYSTEM CONT … MECHANISM OF SWALLOWING/DEGLUTITION MECHANISM OF SWALLOWING/DEGLUTITION CONT … SALIVA FUNCTIONS OF SALIVA FUNCTIONS OF SALIVA CONT … REGULATION OF SALIVARY SECRETION REGULATION OF SALIVARY SECRETION CONT … THE STOMACH AND GASTRIC JUICE CELLS LINING STOMACH CELLS LINING STOMACH CONT … STRUCTRE NERVE SUPPLY TO THE STOMACH FUNCTIONS OF THE STOMACH GASTRIC JUICE FUNCTIONS OF GASTRIC JUICE FUNCTIONS OF GASTRIC JUICE CONT … FOOD DIGESTION IN THE STOMACH REGULATION OF GASTRIC JUICE SECRETION CEPHALIC PHASE GASTRIC PHASE INTESTINAL PHASE GASTRIC SECRETION INHIBITION BY GI HORMONES FACTORS INFLUENCING GASTRIC SECRETION PANCREATIC EXOCRINE SECRETIONS COMPOSITION OF PANCREATIC JUICE FUNCTIONS OF PANCREATIC JUICE REGULATION OF PANCREATIC JUICE SECRETION PHASES OF PANCREATIC JUICE SECRETION HORMONES THAT STIMULATE AND INHIBIT PANCREATIC SECRETION NEURAL REGULATION OF PANCREATIC JUICE SECRETION BILE SALTS FUNCTIONS OF BILE SALTS REGULATION OF BILE SALTS SECRETION FUNCTIONAL ANATOMY OF SMALL INTESTINE FUNCTIONS OF SMALL INTESTINE INTESTINAL VILLI AND GLANDS OF SMALL INTESTINE PROPERTIES AND COMPOSITION OF SUCCUS ENTERICUS FUNCTIONS OF SUCCUS ENTERICUS REGULATION OF SECRETION OF SUCCUS ENTERICUS FUNCTIONAL ANATOMY OF LARGE INTESTINE STRUCTURE OF WALL OF LARGE INTESTINE SECRETIONS OF LARGE INTESTINE FUNCTIONS OF LARGE INTESTINE ABSORPTION IN SMALL AND LARGE INTESTINE KEY ABSORBED SUBSTANCES IN SMALL INTESTINE KEY ABSORBED SUBSTANCES IN SMALL INTESTINE CONT … LARGE INTESTINE: WATER AND ELECTROLYTE RECLAMATION LARGE INTESTINE: WATER AND ELECTROLYTE RECLAMATION CONT … DEFECATION Physiology Of Digestive System PATHWAY FOR DEFECATION REFLEX WHEN YOU START EATING FOODS WITHOUT LABELS, YOU NO LONGER NEED TO COUNT CALORIES FOR PHYSIOLOGY OF DIGESTIVE SYSTEM LEARNING OUTCOMES BY THE END OF THIS SESSION STUDENTS MUST ABLE TO: Describe propulsive and mixing movements of the alimentary canal Describe the mechanism of swallowing(deglutition) Describe composition, functions and regulation of secretion of saliva Describe composition, functions and regulation of secretion of gastric juice Describe composition, functions and regulation of secretion of pancreatic juice Describe composition, functions and regulation of secretion of bile Describe composition, functions and regulation of secretion of the small intestines Describe absorption in the small and large intestines PART I INTRODUCTION Digestion is defined as the process by which food is broken down into simple chemical substances that can be absorbed and used as nutrients by the body. Digestive process is accomplished by mechanical and enzymatic breakdown of food into simpler chemical compounds. While the terms Alimentary Canal and Gastrointestinal (GI) Tract are often used interchangeably to refer to the Digestive System, it's important to understand the distinction: the alimentary canal and GI tract are actually components (building blocks) of the broader Digestive System. FUNCTIONAL ANATOMY OF DIGESTIVE SYSTEM Digestive system is made up of gastrointestinal tract (GI tract) or alimentary canal and accessory organs, which help in the process of digestion and absorption GI tract is a tubular structure extending from the mouth, pass through the thorax, abdomen and pelvis and ends at the anus, with a length of about 30 feet. It opens to the external environment on both ends. GI tract is formed by two types of organs: Primary digestive organs. Accessory digestive organs FUNCTIONAL ANATOMY OF DIGESTIVE SYSTEM CONT … Primary Digestive Organs :are the organs where actual digestion takes place. i. Mouth ii. Pharynx iii. Esophagus iv. Stomach v. Small intestine vi. Large intestine 2. Accessory Digestive Organs: are those which help primary digestive organs in the process of digestion. Accessory digestive organs are: i. Teeth ii. Tongue iii. Salivary glands iv. Exocrine part of pancreas v. Liver vi. Gallbladder. FUNCTIONAL ANATOMY OF DIGESTIVE SYSTEM CONT … WALL OF DIGESTIVE SYSTEM In general, wall of the GI tract is formed by four layers which are from inside out: 1. Mucosa layer (Mucus Layer) 2. Submucus layer 3. Muscular layer 4. Serosa (Serous) or fibrous layer WALL OF DIGESTIVE SYSTEM WALL OF DIGESTIVE SYSTEM Mucosa is the innermost layer made up of three layers The inner epithelium Lamina propria Muscularis mucosae Submucosa,this layer is composed of connective tissue, it contains numerous small glands, blood vessels, and parasympathetic nerves that form the submucosal plexus (Meissner plexus) WALL OF DIGESTIVE SYSTEM CONT .. Muscular is thick layer of smooth muscle tissue which consists of inner circular layer and outer longitudinal layer Between the two layers of muscles there is a nervous plexus called myenteric plexus (Auerbach plexus) Serosa is the outermost layer of made up loose connective tissue (visceral peritoneum) FOOD INTAKE REGULATION Food intake and energy expenditure are key regulators of body weight In humans, food intake is an essential function that is coordinated by the gastrointestinal, endocrine and nervous systems to maintain energy homeostasis The food intake cycle stages are hunger, satiation and satiety Hunger is the desire to eat and it is described as an uncomfortable emptiness in the abdomen. Satiation refers to the sensation of fullness that results in meal termination. Satiety is the term given to the postprandial events that determine the timing for the next meal FUNCTIONS OF DIGESTIVE SYSTEM Digestive system plays the major role in the digestion and absorption of food substances. Thus, the functions of digestive system include: Ingestion or consumption of food substances Breaking them into small particles by Mastication. Transport of small particles to different areas of the digestive tract through Propulsion. Secretion of necessary enzymes and other substances for digestion Digestion of the food particles Absorption of the digestive products (nutrients) Removal of unwanted substances from the body. FUNCTIONS OF DIGESTIVE SYSTEM CONT … Ingestion; taking in food into the stomach through the oral cavity, although liquid can be introduced directly into the stomach by nasogastric tube. Mastication; is the process by which food taken into the mouth is chewed by the teeth and broken down into small particles. Digestive enzymes cannot easily penetrate solid food particles

OPTOMETRY · SEMESTER 1 Renal Physiology Human Anatomy and Physiology START READING NOTES Contents of This Topic INTRODUCTION Renal Physiology INTRODUCTION CONT… FUNCTIONS OF URINARY SYSTEM functions CONT … Kidneys External Anatomy of the Kidney Internal Anatomy of the Kidney Internal Anatomy of the Kidney CONT … Blood Supply of the Kidneys Kidneys CONT … The nephron The nephron CONT … Cortical Nephron Juxtamedullary Nephron Juxtaglomerular Apparatus Juxtaglomerular Apparatus CONT … Formation of urine Formation of urine CONT … Filtration Filtration AND FILTRATION PRESSURES Blood constituents in glomerular filtrate Blood constituents remaining in glomerular capillaries Selective reabsorption Selective reabsorption CONT … Hormones that influence selective reabsorption Hormones that influence selective reabsorption CONT … Atrial natriuretic peptide Tubular secretion Renin–angiotensin–aldosterone system Renin–angiotensin–aldosterone system CONT … Micturition IN INFANTS Micturition IN INFANTS CONT … Micturition IN ADULTS Micturition IN ADULTS CONT … Extracellular Fluid Osmolarity Extracellular Fluid Osmolarity CONT … Components Affecting Extracellular Fluid Osmolarity Sodium and potassium balance Sodium and potassium balance cont … RENAL PHYSIOLOGY INTRODUCTION The urinary system is the main excretory system and consists of the following structures: 2 kidneys, which secrete urine 2 ureters, which convey the urine from the kidneys to the urinary bladder the urinary bladder where urine collects and is temporarily stored the urethra through which the urine passes from the urinary bladder to the exterior. Renal Physiology Urine is excreted from each kidney through its ureter and is stored in the urinary bladder until it is expelled from the body through the urethra. The specialized branch of medicine that deals with structure, function, and diseases of the male and female urinary systems and the male reproductive system is known as nephrology. The branch of surgery related to male and female urinary systems and the male reproductive system is called urology. INTRODUCTION CONT… INTRODUCTION CONT… The urinary system plays a vital part in maintaining homeostasis of water and electrolyte concentrations within the body. The kidneys produce urine that contains metabolic waste products, including the nitrogenous compounds urea and uric acid, excess ions and some drugs. FUNCTIONS OF URINARY SYSTEM The main functions of the urinary system and its components are to Regulate blood volume and composition (e.g. sodium, potassium and calcium) Regulate blood pressure. Regulate pH homeostasis of the blood. Contributes to the production of red blood cells by the kidney. Helps synthesize calcitrol the (active form of Vitamin D). Stores waste product (mainly urea and uric acid) before it and other products are removed from the body. functions CONT … The main functions of the kidneys are: Formation and secretion of urine, which regulates total body water, electrolyte and acid–base balance and enables excretion of waste products Production and secretion of erythropoietin, the hormone that stimulates formation of red blood cells Production and secretion of renin, an important enzyme in the control of blood pressure Kidneys The kidneys lie on the posterior abdominal wall, one on each side of the vertebral column, behind the peritoneum and below the diaphragm. They extend from the level of the 12th thoracic vertebra to the 3rd lumbar vertebra, receiving some protection from the lower rib cage, specifically11th & 12th ribs . The right kidney is usually slightly lower than the left, probably because of the considerable space occupied by the liver. External Anatomy of the Kidney Near the center of the concave medial border of the kidney is a vertical fissure called the hilus, through which the ureter leaves and blood vessels, lymphatic vessels, and nerves enter and exit. Three layers of tissue surround each kidney: the innermost renal capsule, the adipose capsule, and the outer renal fascia. Nephroptosis is an inferior displacement of the kidneys. It most often occurs in thin people. This condition is dangerous because the ureters may kink and block urine flow. Internal Anatomy of the Kidney Internally, the kidneys consist of cortex, medulla, pyramids, papillae, columns, calyces, and pelves. The renal cortex and renal pyramids constitute the functional portion or parenchyma of the kidney. The nephron is the functional unit of the kidney. Internal Anatomy of the Kidney CONT … Parenchyma of kidney renal cortex = superficial layer of kidney renal medulla inner portion consisting of 8-18 cone-shaped renal pyramids separated by renal columns renal papilla point toward center of kidney Drainage system fills renal sinus cavity cuplike structure (minor calyces) collect urine from the papillary ducts of the papilla minor & major calyces empty into the renal pelvis which empties into the ureter Internal Anatomy of the Kidney CONT … Blood Supply of the Kidneys Blood enters the kidney through the renal artery and exits via the renal vein. Kidneys CONT … Kidneys are bean-shaped organs, about 11 cm long, 6 cm wide, 3 cm thick and weigh 150 g. They are embedded in, and held in position by, a mass of fat. A sheath of fibrous connective tissue, also known as the renal fascia, encloses the kidney and the renal fat. The kidneys receive about 20% of the cardiac output. The nephron The nephron consists of a tubule closed at one end, the other end opening into a collecting tubule. The closed or blind end is indented to form the cup-shaped glomerular capsule (Bowman’s capsule), which almost completely encloses a network of tiny arterial capillaries, the glomerulus. The nephron CONT … The loop of Henle consists of a descending limb, a thin ascending limb, and a thick ascending limb. There are two types of nephrons that have differing structure and function. A cortical nephron usually has its glomerulus in the outer portion of the cortex and a short loop of Henle that penetrates only into the outer region of the medulla. A juxtamedullary nephron usually has its glomerulus deep in the cortex close to the medulla; its long loop of Henle stretches through the medulla and almost reaches the renal papilla. Cortical Nephron 80-85% of nephrons are cortical nephrons Renal corpuscles are in outer cortex and loops of Henle lie mainly in cortex Juxtamedullary Nephron 15-20% of nephrons are

OPTOMETRY · SEMESTER 1 Respiratory System Part A Human Anatomy and Physiology START READING NOTES Contents of This Topic Learning Objectives Introduction The Function of the Nose Functions of the pharynx Function of larynx Types of respiration External Respiration Internal Respiration Transport of Oxygen in Blood Stream Oxygen-Haemoglobin Dissociation Curve RESPIRATORY SYSTEM PHYSIOLOGY Learning Objectives 3 Mention the functions of respiratory passageways Explain the types of respiration Describe the mechanism of inhalation and exhalation Describe pulmonary volumes and capacities Learning Objectives Explain alveolar ventilation Describe principles of gas exchange through respiratory membranes Describe transport of oxygen and carbon dioxide between lungs and tissues Describe factors regulating respiration 4 FUNCTIONS OF RESPIRATORY PASSAGEWAYS Introduction The respiratory system is divided into two divisions Upper respiratory tract The organs are located outside of the thorax and consists of the nose, pharynx and larynx Lower respiratory tract The organs are located within the thorax and consists of the trachea, the bronchial tree and the lungs 6 Introduction The main role of the respiratory system is to provide gas exchange between the blood and the environment. Primarily, oxygen is absorbed from the atmosphere into the body and carbon dioxide is expelled from the body. The following are organs from the respiratory system Nose Pharynx Larynx Trachea Bronchi Lungs 7 8 9 The Function of the Nose Respiration (breathing) The nose is the first part of the respiratory system through which the inspired air passes The nose humidify, warming, filtering and cleaning of air Reception and elimination of secretions from the nasal mucosa, paranasal sinuses, and nasolacrimal ducts Olfaction (smelling) The nose is the organ of sense of smell It aids speech- this is enhanced by the presence of paranasal sinuses, which act as resonating chambers for speech 10 Functions of the pharynx Passageway for air and food Warming and humidifying air Protection Taste Facilitates Hearing The pharynx is also important in vocalization and Speech 11 Function of larynx Respiration filters, humidifies and warms air as it passes to the lungs. Swallowing The epiglottis and vestibular folds prevent swallowed material from moving into the larynx Phonation; the vocal folds are the primary source of sound production 12 TYPES OF RESPIRATION Types of respiration Respiration:The exchange of gases between body cells and the environment It involves: Breathing (pulmonary ventilation) Ventilation is the process of moving air into the lungs (inspiration) and out of the lungs (expiration) The flow of air in and out of the lungs require pressure gradient in the opposite direction Exchange of gases in the lungs: external respiration and in the tissues: internal respiration. 14 External Respiration 15 External Respiration External respiration: An exchange of gases by diffusion between the alveoli and the blood in the alveolar capillaries, across the respi­ratory membrane Each alveolar wall is one cell thick and is surrounded by a network of tiny capillaries (the walls of which are also only one cell thick) 16 External Respiration Venous blood arriving at the lungs has travelled from all the tissues of the body, and contains high levels of CO2 and low levels of O2 Carbon dioxide diffuses from the blood down its concentration gradient into the alveoli until equilibrium with alveolar air is reached. By the same process, oxygen diffuses from the alveoli into the blood 17 External Respiration The PO2 within alveoli averages approximately 104mmHg, and as blood flows into the pulmonary capillaries, it has a PO2 of approximately 40mmHg. Consequently, oxygen diffuses from the alveoli into the pulmonary capillary blood because the PO2 is greater in the alveoli than in the capillary blood. 18 External Respiration The slow flow of blood through the capillaries increases the time available for gas exchange to occur. When blood leaves the alveolar capillaries, the oxygen and carbon dioxide concentrations are in equilibrium with those of alveolar air 19 Internal Respiration Internal respiration: An exchange of gases by diffusion between blood in the capillaries and the body cells Gaseous exchange does not occur across the walls of the arteries carrying blood from the heart to the tissues, because their walls are too thick. P02 of blood arriving at the capillary bed is therefore the same as blood leaving the lungs 20 Internal Respiration Blood arriving at the tissues has been cleansed of its CO2 and saturated with O2 during its passage through the lungs, and therefore has a higher P02 and a lower PC02 than the tissues. Carbon dioxide is continually produced as a by-product of cellular respiration, and a diffusion gradient is established from tissue cells to the blood within the tissue capillaries. 21 Internal Respiration The intracellular Pco2 is approximately 46mmHg, and the interstitial fluid Pco2 is approximately 45 mmHg. At the arterial end of the tissue capillaries, the Pco2 is a close to 40 mmHg. As blood flows through the tissue capillaries, carbon dioxide diffuses from a higher Pco2 to a lower Pco2 until equilibrium in Pco2 is established. 22 Internal Respiration At the venous end of the capillaries, blood has a Pco2 of 45 mmHg. CO2 diffuses from the cells into the extracellular fluid, then into the bloodstream towards the venous end of the capillary. 23 TRANSPORT OF OXYGEN AND CARBON DIOXIDE BETWEEN LUNGS AND TISSUES Transport of Oxygen in Blood Stream Transport of blood oxygen and carbon dioxide is essential for internal respiration to occur. Oxygen is carried in the blood in: Chemical combination with haemoglobin as oxyhaemoglobin (98.5%) Solution in plasma water (1.5%). 25 Transport of Oxygen in Blood Stream The amount of O2 in the blood is determined by the amount of dissolved O2, the amount of hemoglobin in the blood, and the affinity of the hemoglobin for O2. In normal adults, most of the hemoglobin molecules contain two alpha and two beta chains Heme 26 Transport of Oxygen in Blood Stream Each of the four iron atoms can bind reversibly one O2 molecule. The iron stays in the ferrous state, so that the reaction is an oxygenation, not an oxidation The reaction is rapid, requiring

OPTOMETRY · SEMESTER 1 Respiratory System Part B Human Anatomy and Physiology START READING NOTES Contents of This Topic Transport of Oxygen in Blood Stream Transport of Carbon Dioxide in Blood Stream Breathing Thoracic diaphragm 17 Inspiration(1) Inspiration(2) 20 Expiration(1) Expiration(2) Expiration(3) A Spirometer Spirometry Pulmonary Volumes Pulmonary Capacities Vital capacity Transport of Oxygen in Blood Stream The pH of blood falls as its CO2 content increases, so that when the PCO2 rises, the curve shifts to the right. In active tissues there is increased production of carbon dioxide and heat, which leads to increased release of oxygen. In this way oxygen is available to tissues in greatest need. When oxygen leaves the erythrocyte, the deoxygenated haemoglobin turns purplish in colour. 2 Transport of Oxygen in Blood Stream The affinity of fetal hemoglobin (hemoglobin F) for O2, which is greater than that for adult hemoglobin (hemoglobin A), facilitates the movement of O2 from the mother to the fetus 3 Transport of Carbon Dioxide in Blood Stream Carbon dioxide is one of the waste products of metabolism It is excreted by the lungs and transported in three mechanisms As bicarbonate ions (HC03-) in the plasma (70%) Some is carried in erythrocytes, loosely combined with haemoglobin as carbaminohaemoglobin (23 %) Some is dissolved in the plasma (7%) 4 Transport of Carbon Dioxide in Blood Stream The solubility of CO2 in blood is about 20 times that of O2; therefore considerably more CO2 than O2 is present in simple solution at equal partial pressures The CO2 that diffuses into red blood cells is rapidly hydrated to H2CO3 because of the presence of carbonic anhydrase 5 Transport of Carbon Dioxide in Blood Stream The H2CO3 dissociates to H+ and HCO3–, and the H+ is buffered, primarily by hemoglobin, while the HCO3– enters the plasma Some of the CO2 in the red cells reacts with the amino groups of hemoglobin and other proteins (R), forming carbamino compounds Since deoxygenated hemoglobin binds more H+ than oxyhemoglobin does and forms carbamino compounds more readily, binding of O2 to hemoglobin reduces its affinity for CO2 (This is known as Haldane effect) 6 Transport of Carbon Dioxide in Blood Stream Venous blood carries more CO2 than arterial blood, CO2 uptake is facilitated in the tissues, and CO2 release is facilitated in the lungs About 7-11% of the CO2 added to the blood in the systemic capillaries is carried to the lungs as carbamino-CO2 In the plasma, CO2 reacts with plasma proteins to form small amounts of carbamino compounds, and small amounts of CO2 are hydrated; but the hydration reaction is slow in the absence of carbonic anhydrase 7 Transport of Carbon Dioxide in Blood Stream Carbon dioxide from tissue diffuses into red blood cells within the capillaries Some of the carbon dioxide binds to haemoglobin, but most of it reacts with water inside the red cells to form carbonic acid, a reaction catalyzed by carbonic anhydrase The carbonic acid then dissociates to form bicarbonate and hydrogen ions 8 Transport of Carbon Dioxide in Blood Stream Since the rise in the HCO3– content of red cells is much greater than that in plasma as the blood passes through the capillaries, about 70% of the HCO3– formed in the red cells enters the plasma The excess HCO3– leaves the red cells in exchange for Cl– This exchange is called the chloride shift 9 Transport of Carbon Dioxide in Blood Stream Because of it, the Cl– content of the red cells in venous blood is therefore significantly greater than in arterial blood The chloride shift occurs rapidly and is essentially complete in 1 second 10 MECHANISM OF INHALATION AND EXHALATION Breathing Breathing (Ventilation): Breathing supply oxygen to the alveoli and eliminate carbon-dioxide Expansion of the chest during inspiration occurs as a result of muscular activity, partly involuntary and partly voluntary. The main muscles used in normal breathing are the intercostals muscles and the diaphragm There are eleven pairs of intercostals muscles that occupy the spaces between the 12 pairs of ribs. 12 Breathing The average respiratory rate is 12 to 15 breaths per minute Each breath consists of three phases Inspiration Expiration Pause 13 Breathing During difficult or deep breathing, muscles of the neck, shoulders and abdomen assist in respiration. These muscles are: sternocleidomastoid and scaleneus muscles- anterior, middle and posterior 14 Thoracic diaphragm The diaphragm is a dome-shaped musculo-fibrous septum which separates the thoracic cavity from the abdominal cavity, its convex upper surface forming the floor of the former, and its concave under surface the roof of the latter. The diaphragm is pierced by a series of apertures to permit of the passage of structures between the thorax and abdomen. 15 Thoracic diaphragm There are three large openings (diaphragmatic hiatus): the aortic the esophageal and the vena cava openings The clinical importance of oesophageal opening is that; weakness can occur and this can cause the development of hiatus hernia The diaphragm is crucial for breathing and respiration The diaphragm is innervated by the phrenic nerve 16 17 Inspiration(0) Inspiration(1) During inspiration, the diaphragm contracts and moves downwards while the external intercostals muscles contracts raising the ribs and elevate the sternum, increasing the size of the thoracic cavity even more This causes expansion of the lungs, as a result, the intra-alveolar pressure falls and the atmospheric pressure forces more air into the airways 18 Inspiration(2) The process of inspiration is active, as it needs energy for muscle contraction. This process is enhanced by the following: Compliance; ability of pulmonary tissue to stretch, making inspiration possible The pressure between parietal and visceral pleura is always less than atmospheric pressure. Elastic coil – tendency of pulmonary tissue to return to a smaller size after having been stretched, passively during expiration 19 20 Expiration(0) Expiration(1) During expiration, the diaphragm and intercostals muscles relax, causing the lungs to recoil, and return to the original shape. This increases the intra-alveolar pressure above the atmospheric pressure, so the air inside the lungs is forced out through the

OPTOMETRY · SEMESTER 1 Respiratory System Part C Human Anatomy and Physiology START READING NOTES Contents of This Topic Functional residual capacity Total lung capacity Inspiratory capacity Dead spaces Physiological dead space Alveolar ventilation Introduction Factors regulating respiration Physiological variables affecting Respiratory membrane Factors that affect the rate of gas diffusion Functional residual capacity Functional residual capacity – the amount of air remaining in the lungs at the end of a normal expiration, therefore it is the sum of ERV + RV = 2.2 -2.4 litres. 2 Total lung capacity Total lung capacity – the sum of all four lung volumes – the total amount of air a lung can hold i.e. = TV+ IVR + EVR + RV = 5.7 – 6.2 litres. 3 Inspiratory capacity Inspiratory capacity is the Tidal volume plus the inspiratory reserve volume 4 Dead spaces Anatomical dead space – air in passageway that do not participate in gas exchange. Dead space:since gaseous exchange in the respiratory system occurs only in the terminal portions of the airways, the gas that occupies the rest of the respiratory system is not available for gas exchange with pulmonary capillary blood. This gas is known to be in dead space 5 Dead spaces Dead space can be: Anatomical dead space – anatomical dead space is the gas in the conducting areas of the respiratory system, such as the mouth, trachea and bronchi where the air doesn't come to the alveoli of the lungs, that do not participate in gas exchange Physiological dead space. 6 Physiological dead space The physiological dead space is equal to the anatomical dead space plus the alveolar dead space Alveolar dead space is the area in the alveoli that does get air to be exchanged, but there is no enough blood flowing through the capillaries for exchange to be effective It is normally very small (less than 5 mL) in healthy individuals. It can increase dramatically in some lung diseases 7 Physiological dead space Physiologic dead space can be measured by Bohr's method. An equation and example are provided below: In physiology, dead space is air that is inhaled by the body in breathing, but does not partake in gas exchange. In adults, it is usually in the range of 150 mL. 8 Alveolar ventilation Alveolar ventilation is the volume of new air that moves into and out of the alveoli per minute. It is equal to the tidal volume minus the anatomical dead space, multiplied by the respiratory rate: 9 Alveolar ventilation Alveolar ventilation per minute is the total volume of new air entering the alveoli and adjacent gas exchange areas each minute. Alveolar ventilation is one of the major factors determining the concentrations of oxygen and carbon dioxide in the alveoli. 10 11 12 FACTORS REGULATING RESPIRATION Introduction Control of respiration is normally involuntary. Voluntary control is exerted during activities such as speaking and singing but is overridden if blood CO2 rises (hypercapnia) 14 Factors regulating respiration The respiratory centre: This is formed by groups of nerve cells that control the rate and depth of respiration They are situated in the brain stem, in the medulla oblongata and the pons influence respiration 15 Factors regulating respiration Central chemoreceptors: These are on the surface of the medulla oblongata and are bathed in cerebrospinal fluid. When the arterial PCO2 rises (hypercapnia), the central chemoreceptors respond by stimulating the respiratory centre, increasing ventilation of the lungs and reducing arterial PCO2. The sensitivity of the central chemoreceptors to raised arterial PCO2 is the most important factor in maintaining homeostasis of blood gases in health. 16 Factors regulating respiration 17 Factors regulating respiration Peripheral chemoreceptors: These are situated in the arch of the aorta and in the carotid bodies They are more sensitive to small rises in arterial PCO2 than Nerve impulses, generated in the peripheral chemoreceptors, are conveyed by the glossopharyngeal and vagus nerves to the medulla and stimulate the respiratory centre. The rate and depth of breathing are then increased. An increase in blood acidity stimulates the peripheral chemoreceptors, resulting in increased ventilation, increased CO2 excretion and increased blood pH. 18 Factors regulating respiration Breathing may be modified by the higher centres in the brain by: speech, singing emotional displays, e.g. crying, laughing, fear drugs, e.g. sedatives, alcohol Sleep Temperature influences breathing: In fever respiration is increased due to increased metabolic rate while in hypothermia it is depressed, as is metabolism. Temporary changes in respiration occur in swallowing, sneezing and coughing. 19 Factors regulating respiration In strenous exercise, both the rate and depth of breathing increase, increasing oxygen uptake and carbon dioxide excretion in order to meet increased needs. 20 Physiological variables affecting respiration Elasticity. Elasticity is the term used to describe the ability of the lung to return to its normal shape after each breath. Loss of elasticity of the connective tissue in the lungs necessitates forced expiration and increased effort on inspiration 21 Physiological variables affecting respiration Compliance. This is a measure of the distensibility of the lungs, i.e. the effort required to inflate the alveoli. When compliance is low the effort needed to inflate the lungs is greater than normal, e.g. in some diseases where elasticity is reduced or when insufficient surfactant is present. It should be noted that compliance and elasticity are opposing forces. 22 Factors regulating respiration Airflow resistance. When this is increased, e.g. in bronchoconstriction, more respiratory effort is required to inflate the lungs. 23 GAS EXCHANGE THROUGH RESPIRATORY MEMBRANES Respiratory membrane 25 Respiratory membrane The respiratory membrane has the following layers : 1. A layer of fluid lining the alveolus and containing surfactant that reduces the surface tension of the alveolar fluid 2. The alveolar epithelium composed of thin epithelial cells 3. An epithelial basement membrane 26 Respiratory membrane 4. A thin interstitial space between the alveolar epithelium and the capillary membrane 5. A capillary basement membrane that in many places fuses with the alveolar epithelial basement membrane 6. The capillary endothelial membrane 27 Factors that affect the