Nephrology (Biology 20) Flashcards
Four functions of the kidney
1) removal of digestive waste products in blood
2) water balance
3) blood pH balance (moving HCO-3 or H+)
4) body salt balance (moving NaCl)
Deamination
Occuring in the liver, this process takes amino acids and turns them into glucose the body can use, often happening at night. The byproduct is toxic ammonia gas, which the body mixes with CO2 to create a less toxic product, urea.
Three steps in the kidneys urine production
1) filtration
2) reabsorption
3) secretion
Aorta
Carries oxygenated blood to the body
Renal artery
Branch of aorta which takes blood to kidneys
Renal vein
Carries blood from kidney to inferior vena cava
Inferior vena cava
Large vein which carries blood to the heart
Ureter
Carries urine from kidney to bladder
Urinary bladder
Stores urine until signalled to release from body (signals emptying at 200 ml; at 600 ml you lose control)
Urethra
Tube which carries urine from bladder out of body
Kidney
Site of blood filtration (cleaning) and urine (waste) production.
Cortex
Outer layer of connective tissue where most of the functional unit, the nephron, is found.
Medulla
Salty layer where the loop of Henle from nephron is found.
Renal pelvis
Hollow chamber where kidney joins ureter. Collects urine and directs it towards the bladder.
Afferent arteriole
Carries blood to the glomerulus.
Efferent arteriole
Carries blood away from the glomerulus
Glomerulus
Network of capillaries where filtration of blood occurs.
- Has small openings in the walls of capillaries that allows filtrate to pass through into nephron tubules
- Small molecules are forced through opening due to pressure created as blood passes through the small capillaries.
- Material that passes through are amino acids, glucose, salt ions, urea, uric acid, and of course, water (large blood proteins and blood cells are too large to cross)
Collecting duct
- ADH also works here as the final chance for the body to reabsorb water if needed and causes urine to become more concentrated.
- Urine (water, salt, urea, uric acid, minerals) is carried to the renal pelvis to be moved into the bladder.
- A hormone called aldosterone from the adrenal gland causes the distal tubule and collecting duct to increase Na+ reabsorption by active transport (Cl- follows passively) to maintain the bodies salt balance.
- Also causes K+ to be secreted into the distal tubule if too high in blood.
Proximal tubule
First part of tubule following Bowman’s capsule where 65% of filtrate is reabsorbed.
- Glucose, amino acids, NaCl, are immediately reabsorbed back into blood through active transport, and K+ by passive transport.
- Water moves by osmosis with these substances as it follows the osmotic gradient
- Bicarbonate ions (move out passively) and H+ (move in with active transport) move to help control blood pH.
Bowman’s capsule
Funnel shaped part of nephron which surrounds glomerulus; collects filtrate from glomerulus and moves it to tubules.
Descending loop Henle
Permeable to water, so reabsorption of water by osmosis here, which concentrates filtrate.
Ascending loop of Henle
- Thin segment permeable to salt, so NaCl passively moves out of tubule and into medulla.
- Thick segment requires active transport to continue moving NaCl out of tubule and into medulla (Na+ moves by active transport and Cl- ions follow passively)
- 2/3 of Na+ and water is reabsorbed by now.
Distal tubule
active transport used to regulate the amount of NaCl and K+ in the blood; if needed, NaCl can be moved out and K+ can be secreted into tubule (excess in blood) - both by active transport.
- pH of blood also controlled here by either secreting (active transport) H+ into the tubule, or reabsorbing (this time with active transport) bicarbonate ions (HCO3- out of tubule by osmosis (alchohol decreases ADH release, so more water is urinated out)
- Materials not normal to the body (penicillin, drugs) and excess of other (ammonia, uric acid, histamines) are secreted here.
What systems regulate body fluid levels?
The nervous system and endocrine system.
What receptors detect blood osmotic pressure?
Osmoreceptors in the hypothalamus
ADH
Hypothalamus sends message to pituitary gland in brain to release the hormone, which causes the distal tubule and collecting duct to become more permeable to water.
Aldeosterone
Responsible for regulating blood pressure - stimulates nephrons to reabsorb NaCl, which increases the osmotic gradient and causes more water to move out of the nephrons into the blood.
