11. Urinary System Flashcards
The tubes that connect the kidneys to the bladder
Ureters
The tube exiting the bladder to remove urine from the body
Urethra
List 4 functions of the urinary system
- Excretion of unwanted substances
- Maintenance of water & electrolyte balance
- pH regulation of body fluids
- Production of hormones
- Regulation of red blood cell production
- Regulation of blood glucose levels
- Regulation of blood pressure, volume and osmolarity
What gas is found in all metabolic waste products?
Nitrogen
List the 3 metabolic waste products.
- Urea (from protein metabolism)
- Uric Acid (from purine metabolism)
- Creatine (from muscle metabolism)
What is the main ion excreted in urine?
Hydrogen (H+)
What is the minimum urine content required to clear body waste?
500 ml/day
What are electrolytes?
Charged atoms in solution
Name the 3 most important electrolytes that are regulated by the kidney.
Sodium (Na+)
Potassium (K+)
Hydrogen (H+)
An excess in what electrolyte is a reflection of an acidic solution?
Hydrogen (H+)
What pH should blood be?
7.35 - 7.45
What are the two primary pH control systems in the body and how do they work?
- Lungs - excrete CO2 through respiration
- Kidneys - excrete H+ into urine and produce the buffer HCO3 (bicarbonate)
What are the two main hormones produced by the kidneys and what are their functions?
Calcitriol - the active form of vitamin D that increases bone formation by increasing calcium.
Erythropoietin - stimulates erythropoiesis
How does calcitriol increase bone formation?
1) Stimulates calcium and magnesium update in the GIT
2) Reduces calcium loss in the kidneys
Bone formation increases due to the increase in calcium.
What hormone is released by the kidneys in response to hypoxia?
Erythropoietin
In renal failure, erythropoietin production is inadequate and hence results in what pathology?
Anaemia
What is the renal threshold for glucose?
9 mmol/L
What is a normal blood glucose level?
4 - 7 mmol/L
How do the kidneys make glucose?
The kidneys are able to make glucose from the amino acid glutamine to help elevate blood sugar levels when hypoglycemia.
NB this is called gluconeogenesis
How do the kidneys control blood volume, pressure and concentration?
1) Conserving or eliminating water in urine.
2) Regulating the solute loss in the urine helps maintain a constant blood concentration.
3) Secrete the enzyme renin which activates the renin-angiotensin-aldosterone pathway increasing blood pressure.
Where are the kidneys located?
- Partially protected by the 11th & 12th ribs.
- Between vertebra levels T11 - L3
- Right kidney is lower because the liver occupies space on the right.
What are the 3 layers surrounding the kidney?
1) Renal capsule - deep later of connective tissue
2) Adipose capsule - middle layer of fatty tissue
3) Renal fascia - superficial layer of connective tissue
What are the two regions within the kidneys?
1) Renal cortex - superficial, light red area
2) Renal medulla - dark area consisting of several cone-shaped structures
Describe the functional portions of the kidneys.
Several cone-shaped structures called renal pyramids.
The apex of each renal pyramid is called the renal papilla.
What is the term for the function unit of the kidneys and how many are there in each kidney?
Nephrons
1 million per kidney
Name the artery and vein going in and out of the kidneys.
Renal artery and vein
Name the two parts of a nephron.
1) Renal corpuscle
2) Renal tubule
Describe the route urine travels once it’s formed
Once formed within the nephrons, urine drains into the renal papilla, then into the minor and major calyces.
From there, urine travels out of the kidney into the ureter, into the bladder, and then the urethra.
Name the artery and vein going in and out of the kidney
Renal artery and vein
Describe what the renal corpuscle consists of.
Consists of the glomerulus & Bowman’s capsule:
The glomerulus is a tangled capillary network that receives blood from an afferent arteriole and is 50x more leaky than normal capillaries.
The Bowman’s capsule is a double-walled epithelial cup that surrounds the glomerulus and receives contents of filtered blood.
Name the 3 sections of the renal tubule and their location in the kidney
1) Proximal convoluted tubule
2) Loop of Henle
3) Distal convoluted tubule
Proximal and distal convoluted tubules sit in the renal cortex.
The Loop of Henle often extends into the renal medulla.
What is the overall role of the renal tubule?
Filtered fluid passes through the tubules where the reabsorption and secretion of various solutes occur.
What part of the nephron does antidiuretic hormone (ADH) act on?
Distal convoluted tubule
What are the arterioles that enter and exit the nephron called?
Afferent arteriole (entering)
Efferent arteriole (exiting)
What prevents the backflow of urine from the bladder back into the ureters?
A physiological valve
Name and briefly describe the 3 layers of tissue that form the wall of the ureters.
1) Inner mucous membrane
Transitional epithelium that can stretch, along with goblet cells secreting mucous for protection.
2) Muscularis
Smooth muscle fibres for peristaltic contractions
3) Adventita
Outer coating of connective tissue with blood and lymph vessels, and nerves.
What is the total capacity of the bladder and at what point does the desire to urinate occur?
Total capacity is 600-700ml
Desire to urinate from about 200ml
What is the triangular area on the posterior floor of the bladder called and what is found there?
Called the trigone.
The two ureteral openings enter here along with the urethral opening at the base.