Urinary system Flashcards
What is X?
Kidney
What is X?
Ureter
What is X?
Urethra
What is X?
Renal artery
what are the main functions of the urinary system
filter out waste, toxins and excess water from the blood, and excrete it through urine
regulate fluid balance and electrolytes (BP)
regulate pH (homeostasis)
produce vit D
stimulate RBC production
what is A and what is its function?
renal artery- to transport oxygenated blood away from the heart, to the kidney
what is B and what is its function?
renal vein- to transport deoxygenated blood from the kidney to the heart
what is D and what is its function?
renal pelvis- stores urine before sending it to the bladder via the ureter
what is E and what is its function?
medulla- regulates concentration of urine
what is F and what is its function?
cortex- outer layer that protects medulla and renal pelvis
What is the function of the bladder?
To store urine
What is the function of the kidneys?
to regulate blood volume
to filter blood by removing pathogens
What is X?
Bladder
structure and function of a nephron
S= microscopic structural and functional unit of the kidney
F= filter blood and reabsorb substances into the blood based on need
What is A 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 (then descending loop of henle absorbs water and ascending absorbs salts to regulate BP)
NB can be passive or active depending on conc grad
What is B and what is its function?
afferent arteriole
to deliver blood to the glomerulus for filtration
What is C and what is its function?
glomerulus
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 function?
efferent arteriole
to transport filtered blood from the glomerulus back to general circulation (RBC and platelets remain in the blood)
What is E and what is its function?
Bowman’s capsule
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 F 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 G and what is its function?
collecting duct
to collect urine from the nephrons and transport it to the renal pelvis
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?
ascending loop of Henle
to reabsorb salts which attract water to regulate blood volume and hence BP
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)
describe the thirst response
osmoreceptors in the hypothalamus detect insufficient water levels in the body –> thirst centre in hypothalamus stimulates –> increased thirst –> increased water consumption
ADH (Anti-diuretic hormone)
produced by hypothalamus
secreted by pituitary gland
increases membrane permeability of the distal convoluted tubule and collecting duct of nephron of the kidney
increases water absorption into blood via aquaporins
increases concentration of urine
decreases urine output
Aldosterone
secreted by adrenal gland
increases reabsorption of salt and therefore water
ANP (Atrial natriuretic peptide)
secreted by atria of the heart in response to high BP
decreases reabsorption of sodium and water
glomerular filtration
high pressures in the glomerulus pushes small molecules eg.glucose in the blood through the permeable capillary walls of the bowmen’s capsule into the proximal convoluted tubule
selective reabsorption
occurs in proximal convoluted tubule
selective reabsorption of substances eg. glucose from glomeral filtrate into the blood based on need via PERITUBULAR CAPILLARIES
tubular secretion
occurs in distal convoluted tubule
eliminates excess unwanted substances not already in the filtrate to form urine and is sent to the collecting ducts
The bladder is able to expand as urine accumulates within it due to the presence of
Transitional epithelium
3 systems involved in the elimination of wastes + waste products
Digestive—> faeces
Urinary —> urine, urea, water
Respiratory—> CO2
What is the function of urethra?
To transport urine from the bladder to the outside of the body (pathway) excretion
What is the function of ureters?
To transport urine from the kidneys to the bladder via peristalsis
Glomerular capillaries
produce filtrate
Peritubular capillaries
reclaim filtrate
ACID BASE BALANCE IS CONTROLLED SEQUENTIALLY BY:
1) Chemical buffers
2) Respiratory mechanisms
3) Renal mechanisms
Three Major Chemical Buffer Systems:
- Protein Buffer System
- Phosphate Buffer System
- Carbonic Acid-Bicarbonate Buffer System
Protein Buffer System
- Buffers intracellular fluid
- Largest buffering system.
- Release or accept H+
Phosphate Buffer System
- Buffers intracellular and extracellular fluid.
- Buffer pH of urine and ICF
- Phosphate molecules (i.e., DNA)
Carbonic Acid-Bicarbonate Buffer System
- Buffers extracellular fluid.
- Protect against effects of acids generated during metabolism.
- Binds or releases hydrogen.
- IF EXCESS: Bicarbonate (HCO3-) binds with excess H+
- IF SHORT: Carbonic acid (H2C03) disassociates to form hydrogen and bicarbonate ions.
Respiratory Regulation
A decrease in the CO2 concentration, decreases the H+ Concentration (INCREASES BLOOD PH) –> INCREASES RESPIRATION RATE
An increase in CO2 concentration, increases the H+ Concentration (DECREASES BLOOD PH) –> DECREASES RESPIRATION RATE
Renal Regulation
- Kidneys secrete H+
- Slow
- Only way to eliminate acids is through urine.
Acidosis
(Plasma [H+] increases)
the kidneys pump out more H+ and retrieve more bicarbonate.
Alkalosis
(Plasma [H+] decreases)
the kidneys excrete less H+ ions and retrieve less bicarbonate.
RENIN ANGIOTENSIN ALDOSTERONE SYSTEM (RAS)
- Renin is produced by juxtaglomerular cells of the nephron in the kidneys in response to =
- Sympathetic NS is activated.
- Decrease stretch, due to decreased blood pressure and volume. - Once renin is in the bloodstream, it will cleave angiotensinogen into angiotensin I.
- Angiotensin I is converted to angiotensin II through the enzyme angiotensin-converting enzyme (ACE) in the lungs
a. Angiotensin II will do two things . . .
i. Vasoconstriction of blood vessels, increasing blood pressure.
ii. Increase antidiuretic hormone release by the posterior pituitary gland, this increases thirst, water reabsorption by the kidneys, and an increase in blood volume. - Angiotensin II increases the release of aldosterone by the adrenal glands.
a. aldosterone will promote sodium reabsorption in the kidneys which, together with the ADH release from the angiotensin II, iresults in an increased water reabsorption
