11. URINARY SYSTEM Flashcards
List four functions of the urinary system
- Excretion of waste: Uric acid, urea, toxins
- Maintenance of water & electrolyte balance
- pH regulation of body fluids (especially blood)
- Production of hormones (erythropoietin & calcitriol)
- Regulation of red blood cell production.
- Regulation of blood glucose levels.
- Regulation of blood pressure, volume and osmolarity (concentration of a solution)
Name three metabolic wastes containing nitrogen excreted by the urinary system.
Urea
Uric acid
Creatinine
Name one ion excreted by the kidneys
Hydrogen
State the minimum daily quantity of urine (ml) required to clear body waste.
500ml
What is creatine phosphate?
A protein based molecule that stores ATP to be used by muscles.
What is the waste product formed from the metabolism of creatine phosphate in muscles?
Creatinine
Name three electrolytes regulated by the kidneys
Sodium (Na+)
Potassium (K+)
Hydrogen (H+)
Describe specifically how the kidneys play a role in blood pH balance.
The kidneys excrete H+ into urine and produce the buffer HCO3 (bicarbonate) to counter blood acidity.
Describe the main role of the following hormones in relation to the kidney:
a. Calcitriol
b. Erythropoietin
a. The kidneys convert inactive Vitamin D into its active form (Calcitriol) which stimulates the uptake of calcium and magnesium from the GIT and reduces the calcium loss from the kidneys.
b. Erythropoietin (EPO) is a hormone that the kidneys produce in response to hypoxia and it stimulates erythropoiesis in the red bone marrow.
Explain why anaemia is common in renal failure
The lack of the production of erythropoietin leads to inadequate red blood cell levels and hence results in anaemia.
What range of blood glucose levels is considered as normal?
4-7 mmol/L
State the normal renal threshold for glucose in mmol/L
9 mmol/L [above this level in the blood, glucose cannot be reabsorbed from the nephrons into the blood when passing through kidney tubules]
Describe specifically how the kidneys compensate for ‘low blood glucose’
Through a process known as gluconeogenesis, the kidneys are able to make glucose from the amino acid glutamine, in order to raise blood glucose levels during periods of hypoglycaemia.
What pathology is ‘hyperglycaemia’ indicative of?
Diabetes Mellitus
What enzyme is secreted by the kidneys to help regulate blood pressure?
Renin
Explain why the right kidney is lower than the left kidney
The right kidney is lower than the left because the liver occupies considerable space on the right side of the body, superior to the kidney.
Are the kidneys positioned within or outside the peritoneum?
Outside - they are retroperitoneal
What are the three layers of tissue that surround the kidneys?
- Renal capsule (deep layer) - smooth, transparent connective tissue
- Adipose capsule (middle layer) - mass of fatty tissue that protects and supports
- Renal fascia (superficial layer) - anchors kidneys to surrounding structures
Name the two distinct regions in the kidney
Renal cortex
Renal medulla
What is the functional units of the kidney called?
nephrons
Urine formed by the nephrons drain into the ______ and major _______.
minor
calyces
Explain what is meant by the ‘hilum’
The hilum is the concave medial border of the kidney where blood vessels, lymph vessels, nerves and ureters enter the kidney.
What % of cardiac output is received by the kidneys?
20-25%
Name the two parts that make up the nephron
The renal corpuscle and the renal tubule.
Where can the peritubular capillaries be found?
Surrounding the proximal and distal tubule and loop of henle of the nephron.
State which of the following components are in the ‘renal tubule’ or ‘renal corpuscle’:
a. Loop of Henle
b. Distal convoluted tubule
c. Bowman’s capsule
d. Proximal convoluted tubule
e. Glomerulus
a. Tubule
b. Tubule
c. Corpuscle
d. Tubule
e. Corpuscle
Name the specific location in a nephron where anti-diuretic hormone acts.
Distal convoluted tubule
Describe the role of the ‘muscularis’ in the ureter
The muscularis consists of smooth muscle fibres and is responsible for the peristaltic contractions that propels the urine.
State the volume of urine (ml) which, when exceeded within the bladder, triggers the desire to urinate.
200ml
Name the small triangular area located on the posterior floor of the bladder.
The trigone
Is the internal urethral sphincter voluntary or involuntary? Which muscle forms this sphincter?
Involuntary. The muscularis of the bladder, also known as the ‘detrusor’.
List two differences between the female and male urethras.
The female urethra is 4cm long whilst the male urethra is about 20cm long. The male urethra passes through the prostate, where it receives semen during ejaculation.
Name the smooth muscle found in the bladder wall
The detrusor muscle
Name three processes involved in urine formation
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
Name the specific location in a nephron where anti-diuretic hormone acts.
Distal convoluted tubule
How is urine transported from the renal pelvis to the urinary bladder?
Two ureters transport urine from the renal pelvis to the bladder. There is peristaltic contractions of the ureters’ muscular walls that propels the urine forward, aided by gravity and the pressure of the urine.