Optometry Semester 1

OPTOMETRY · SEMESTER 1 Brain, Cranial Nerve And Supply Human Anatomy and Physiology START READING NOTES Contents of This Topic General structure of NS (1) General structure of NS Brain, Cranial Nerve And Supply General structure of NS (4) General structure of NS (5) Neuroglia in the CNS include astrocytes, microglial cells, ependymal cells and oligodendrocytes. Ependymal cells are another glial subtype that line the ventricles of the CNS to help circulate the CSF. The Brain: The largest part of the human brain is the cerebrum, which consists of two hemispheres separated by the longitudinal fissure. The cerebral cortex is divided into lobes that have the same names as the cranial bones external to them The Precentral (Motor) Area The Brain: Cerebrum (Specialized areas) cont.. The Parietal Area Auditory Area Visual Area The Brain: Thalamus Also called Basal ganglia The Brain: Hypothalamus The Brain: Cerebellum The Brain: Brainstem Pons Other special features in medulla oblongata Ventricular System of the Brain Communicate through holes or foramen as summarized below Fourth ventricle Cerebro-Spinal Fluid (1) Cerebrospinal fluid is formed by choroidal epithelial cells of the choroid plexuses in the lateral, 3rd, and 4th ventricles Flow of CSF (1) CSF also passes into the extensions of the subarachnoid space around the cranial nerves. Cranial nerves Olfactory nerve (I) Optic nerve (II) Optic nerve (II) cont.. Oculomotor nerve (III) Trochlear nerve (IV) Trigeminal nerve (V) Abducens nerve (VI) Facial nerve (VII) Vestibulocochlear nerve (VIII) Glossopharyngeal nerve (IX) Vagus nerve (X) Accessory nerve (XI) Hypoglossal nerve (XII) Blood supply of the head and neck Common Carotid Artery Carotid Sinus Relations External Carotid Artery Branches Superior Thyroid Artery Ascending Pharyngeal Artery Lingual Artery Facial Artery Occipital Artery Posterior Auricular Artery Superficial Temporal Artery Maxillary Artery Branches of Maxillary Artery Internal Carotid artery Arterial blood supply to the brain Anterior choroidal artery Vertebral arteries Meningeal branch –supplying falx cerebelli,a sheet of dura matter The two arteries converge to form the basilar artery Arterial circle of willis Circle of willis Three main branches of circle of Willis To complete the circle two connecting vessels are also present External Jugular Vein Anterior Jugular Vein Internal Jugular Vein Tributaries of Internal Jugular Vein Lymphatic drainage of the head and neck INTRODUCTION INTRODUCTION CONTD… SUPERFICIAL LYMPH NODES SUPERFICIAL CERVICAL NODES ANTERIOR CERVICAL NODES DEEP LYMPH NODES NODES OF MIDLINE DEEP CERVICAL LYMPH NODES DEEP CERVICAL LYMPH NODES CONTD… UPPER DEEP CERVICAL LYMPH NODES LOWER DEEP CERVICAL LYMPH NODES LOWER DEEP CERVICAL LYMPH NODES CONTD… LYMPH NODES OF HEAD &NECK LYMPH NODES OF HEAD &NECK CONTD… PRELARYNGEAL NODES SUBMENTAL NODES SUBMANDIBULAR NODES SUBMANDIBULAR NODES CONTD… SUBMANDIBULAR NODES CO NTD… BUCCAL NODES PAROTID (PREAURICULAR) NODES MASTOID (POSTAURICULAR) NODES MASTOID (POSTAURICULAR) NODES CONTD… OCCIPITAL NODES HEAD AND NECK General structure of NS (1) The nervous system has two divisions. The central nervous system (CNS) consists of the brain and spinal cord. The peripheral nervous system (PNS) consists of cranial nerves and spinal nerves. The PNS includes the autonomic nervous system (ANS). The brain is contained within the cranial cavity of the skull, and the spinal cord is contained within the vertebral cavity of the vertebral column. General structure of NS Nervous tissue, present in both the CNS and PNS, contains two basic types of cells: neurons and glial cells. Neurons are cells and therefore have a cell body, axon and the dendrite. Looking at nervous tissue, there are regions that predominantly contain cell bodies and regions that are largely composed of just axons. These two regions within nervous system structures are often referred to as gray matter (the regions with many cell bodies and dendrites) or white matter (the regions with many axons). Brain, Cranial Nerve And Supply A localized collection of neuron cell bodies in the CNS is referred to as a nucleus. In the PNS, a cluster of neuron cell bodies is referred to as a ganglion. A bundle of axons, or fibers, found in the CNS is called a tract whereas the same thing in the PNS would be called a nerve. In the peripheral nervous system, axons and dendrites are “wrapped” in specialized cells called Schwann cells General structure of NS (3) General structure of NS (4) Neurons may be classified into three groups: sensory neurons, motor neurons, and interneurons. Sensory neurons (or afferent neurons) carry impulses from receptors to the central nervous system. Interneurons are found entirely within the central nervous system. They are arranged so as to carry only sensory or motor impulses, or to integrate these functions. Motor neurons (or efferent neurons) carry impulses from the central nervous system to effectors General structure of NS (5) Glial cells oA supportive cell in the central nervous system. oUnlike neurons, glial cells do not conduct electrical impulses. oThe glial cells surround neurons and provide support for and insulation between them. oGlial cells are the most abundant cell types in the central nervous system. Types of glial cells include oligodendrocytes, astrocytes, ependymal cells, Schwann cells, microglia, and satellite cells. Neuroglia in the CNS include astrocytes, microglial cells, ependymal cells and oligodendrocytes. Neuroglia in the PNS include Schwann cells and satellite cells. Astrocytes support and brace the neurons and anchor them to their nutrient supply lines. They also play an important role in making exchanges between capillaries and neurons. Microglial cells can transform into a special type of macrophage that can clear up the neuronal debris, while monitoring the health of the neuron. General structure of NS (6) Ependymal cells are another glial subtype that line the ventricles of the CNS to help circulate the CSF. Oligodendrocytes are cells that wrap their process tightly around the fibers producing an insulating covering called myelin sheath. Schwann cells are similar in function to oligodendrocytes and microglial cells. Satellite cells perform a similar function to astrocytes General structure of NS (7) The Brain: The brain constitutes about 2% of the body weight and lies within the cranial cavity, the parts are: Cerebrum Cerebellum Brain stem Midbrain Pons Medulla oblongata The largest part of

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

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 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 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