Structure and Functions of the Urinary System – PST04103 Human Anatomy and Physiology
NTA Level 4 • Semester 1 • PST04103 Structure and Functions of the Urinary System Human Anatomy and Physiology • Source Session/Topic 30 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 30: Structure and Functions of the Urinary System Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define the Urinary System • List Structures of Urinary System • Describe the Structures of the Urinary System • Explain the Functions of the Structures of the Urinary System Resources Needed: • Flip charts, marker pens, and masking tape • Black/white board, chalk and whiteboard markers • Overhead projector (OHP) and computer SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 | |Presentation |Definition and Type of Structures of| | |25 minutes |Brainstorming |the Urinary System | |3 | |Presentation |Structures of the Urinary System | | |50minutes | | | |4 |30 minutes |Presentation |Functions of the Structures of the | | | |Buzzing |Urinary System | |5 |05 minutes |Presentation |Key Points | | 6 |05 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning tasks and clarify ASK students if they have any questions before continuing STEP 2: Definition of the Urinary System (25 minutes) |Activity: Brainstorming (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What is urinary system? | |What are the structures of urinary system? | | | |ALLOW few students to respond | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARISE by using the content below | Urinary system: is the system which regulates the content of blood plasma to maintain the homeostasis of the internal fluid environment within normal limits (control the composition of blood and blood volume) • It removes waste products from the blood, of which many of them are toxic • The principal organ of the urinary system is the kidney • The accessory organs include the ureters, urinary bladder and urethra • The following are the structures of the urinary system: o Kidneys o Ureters o Urinary bladder, o Urethra STEP 3: Structures of the Urinary System (50 minutes) The kidneys • Are bean shaped organs with a medial indentation, • located in the upper abdominal cavity on either side of the vertebral column, behind the peritoneum • Are embedded in adipose tissue that acts as a cushion and is in turn covered by a fibrous connective tissue membrane called the renal fascia, which helps hold the kidneys in place • The renal artery enters the kidney, and the renal vein and ureter emerge • The outer tissue layer is called the renal cortex, which is made of renal corpuscles and convoluted tubules • The inner tissue layer is the renal medulla, which is made of loops of henle and collecting tubules • The renal medulla consists of wedge-shaped pieces called renal pyramids. • The tip of each pyramid is its apex or papilla • Renal pelvis is a cavity formed by the expansion of the ureter within the kidney at the hilus • Funnel shaped extensions of the renal pelvis; called calyces enclose the papillae of the renal pyramids • Urine flows from the renal pyramids into the calyces, then to the renal pelvis and out into the ureter Nephron o Nephron is the structure and function unit of the kidney o It is well associated with the blood vessels and the urine is formed there o Each nephron has two major portions: a renal corpuscle and a renal tubule Renal corpuscle ▪ Consists of a glomerulus surrounded by a Bowman’s capsule. ▪ The glomerulus is a capillary network that arises from an afferent arteriole and empties into an efferent arteriole. ▪ The diameter of the efferent arteriole is smaller than that of the afferent arteriole, which helps maintain a fairly high blood pressure in the glomerulus. Bowman’s capsule ▪ Is the expanded end of a renal tubule and encloses the glomerulus. ▪ The fluid that is formed from the blood in the glomerulus will eventually become the urine The renal tubule o Continues from Bowman’s capsule and consists of the proximal convoluted tubule (in the renal cortex), loop of Henle (in the renal medulla), and distal convoluted tubule (in the renal cortex). o The distal convoluted tubules from several nephrons empty into a collecting tubule. o Several collecting tubules then unite to form a papillary duct that empties urine into a calyx of the renal pelvis. [pic] Source: F.A.Davis (2007). Figure 30.1: Structure of the kidney o Blood flow and urine formation o Blood enters the kidney through the renal artery and flows downstream to afferent arterioles and emerge through efferent arterioles, flowing to upper stream to renal veins, and finally to inferior vena cava o The formation of urine involves three major processes ▪ The first is glomerular filtration, which take place in the renal corpuscles and ▪ The second and third are tubular reabsorption and tubular secretion, which take place in the renal tubules. o Accessory organs of the urinary system o The ureters, urinary bladder, and urethra are responsible for the periodic elimination of urine and do not change the composition or amount of urine. o Ureter ▪ Each ureter extends from the hilus of a kidney to the lower, posterior side of the urinary bladder ▪ The smooth muscle in the wall of the ureter contracts in peristaltic waves to propel urine toward the urinary bladder. ▪ As the bladder fills, it expands and compresses the lower ends of the ureters to prevent backflow of urine. o Urinary bladder ▪ It is a muscular sac