Urinary System Flashcards
What is A and what is its structure and function?
Kidney
- S = bean-shaped organ, the size of a fist. Kidneys are retroperitoneal and the right kidney sits more inferior
- F = filter metabolic wastes out of blood to forming urine, secrete erythropoietin (hormone for RBC formation), produce renin (BP regulation), metabolise Vit D to its active form
What is C and what is its function?
Renal artery
- To transport oxygenated blood away from the heart, to the kidney
What is D and what is its function?
Renal vein
- To transport deoxygenated blood from the kidney to the heart
What is B and what is its function?
Medulla
- Regulates concentration of urine
What is A and what is its function?
Cortex
- Outer layer that protects medulla and renal pelvis
What is F and what is its function?
Renal pelvis
- Stores urine before sending it to the bladder via the ureters
Structure and function of a nephron
- S = microscopic structural and functional unit of the kidney
- F = filter blood and reabsorb needed substances into the blood
What is A and what is its function?
Afferent arteriole
- To deliver blood to the glomerulus for filtration
What is B and what is its function?
Efferent arteriole
- To transport filtered blood from the glomerulus back to general circulation (RBC and platelets remain in the blood)
What is C and what is its structure and function?
Glomerulus
- S = tuft of capillaries with small holes
- F = glomerular filtration: high pressure pushes small molecules (e.g. water, salts, amino acids) through the semi-permeable capillary walls and the Bowman’s capsule into the proximal convoluted tubule. Large substances e.g. blood cells and platelets should not pass through the capillary walls.
What is D and what is its structure and function?
Bowman’s capsule
- S = membranous, double walled capsule which surrounds the glomerulus
- F = receives the glomerular filtrate e.g. H2O, NaCl, amino acids, which passes through to the proximal convoluted tubule, NOT blood cells and platelets
What is E and what is its function?
Distal convoluted tubule
- Eliminate excess unwanted substances not already in filtrate e.g. K+, drugs, H+ ions (pH regulation), to form urine which is sent to the collecting duct
What is F and what is its function?
Proximal convoluted tubule
- Selective reabsorption of substances (water, glucose, amino acids, salts) from the glomerular filtrate back into the blood, based on need
NB can be passive or active depending on conc grad
What is G and what is its function?
Ascending loop of Henle
- To reabsorb salts which attract water to regulate blood volume and hence BP
What is H and what is its function?
Descending loop of Henle
- To reabsorb water to regulate blood volume and hence BP (this occurs first since water is more important than salt)
What is I and what is its function?
Collecting duct
- To collect urine from the nephrons and transport it to the renal pelvis
State the 3 steps (in order) of urine formation and where they occur
- Glomerular filtration (glomerulus and Bowman’s capsule)
- Selective reabsorption (proximal convoluted tubule and loop of Henle)
- Tubular secretion (distal convoluted tubule)
Features of healthy urine
- Clear, straw-coloured liquid due to excretion of bile pigments
- Large majority is water with some excreted wastes
What is B and what is its structure and function?
Ureter
- S = tubes consisting of a fibrous outer layer, smooth muscle and mucous membrane that connect the kidneys to the bladder
- F = to transport urine from the renal pelvis (kidney) to the bladder via peristalsis
What is C and what is its structure and function?
Bladder
- S = a distensible muscular sac (can contract and relax) which contains a detrusor muscle (allows it to contract to empty) and transitional epithelium (allows it to expand). Sphincters control the release of urine.
- F = to store urine prior to voiding (urination)
What happens to the bladder as people age?
Bladder capacity and tone decrease, leading to incontinence (leakage of urine) and more frequent micturition (urination)
What is D and what is its structure and function?
Urethra
- S = muscular tube that extends from the bladder to the outside of the body, surrounded by sphincters (male is longer, runs within the prostate gland and transports both urine and semen whereas female is shorter, only transports urine)
- F = to excrete urine from bladder to outside of the body