Kidney and renal function Flashcards
Excretion, homeostatic and regulatory functions of the kidneys.
Excretions:
- Removes endogenous waste products
- Removes drugs and their metabolites
Homeostasis:
- Water and electrolyte balance
- Acid/base balance
Regulation:
Production of hormones like EPO and renin.
Cortical nephrons
Type of nephron in the cortex.
- Makes up most of the nephrons in the kidneys [70-80%]
Has a short loop of Henle in the medulla.
Juxtamedullary nephrons
Type of nephron that is closer to the medulla.
- Loop of Henle extends deep into the medulla.
- Makes urine more concentrated by developing steeper osmotic gradients.
Fewer than cortical nephrons- 20-305.
Pathway of blood supply to kidneys
Abdominal aorta—-> Renal artery —-> Segmental artery ——> Interlobar arteries—–> Arcuate arteries—–> Interlobular arteries——> Afferent arterioles—–> Glomerulus —–> Efferent arterioles
Pathway of blood drainage from kidneys
Peritubular capillaries—–> Venules—–> Interlobular veins —-> Arcuate veins—> Interlobar veins —-> Renal vein
Blood supply to nephrons
Afferent arterioles drain into glomerulus.
- Efferent drains away from glomerulus.
Peritubular capillaries run with nephrons- especially loop of Henle
Vasa recta
Capillaries that run parallel to the loop of Henle
Sympathetic supply to kidneys
- Effects of innervation
Postganglionic fibres from sympathetic chain- splanchnic nerves.
- Fibres from coeliac ganglion
Stimulates reduction in blood supply during stress
Paraympathetic supply to kidneys
- Effects of innervation
Renal plexus at hilum contains fibres from vagus nerve
- Control tone of efferent arterioles
- Modifies GFR and renal blood flow
Three major functions of the kidney
Filtration of blood.
Reabsorption:
- water
- ions
- organic nutrients
Secretion of waste
Glomerular filtration
First step of filtration at glomerulus into Bowman’s capsule.
Small molecules filtered:
- Electrolytes
- Amino acids
- Glucose
- Metabolic waste
- Some drugs and its metabolites
Large molecules and cells stay in the blood.
Tubular reabsorption
More than 99% of water and electrolytes filtered are reabsorbed back into the blood.
Water:
Down osmotic gradient into aquaporins.
Gradient created by Na+.
Na+ and other ions:
Down electrochemical gradients.
Cotransport:
Such as glucose and Na+
Active reabsorption:
Uses ATP- like Na+K+-ATPase
Absorption can be paracellular or transcellular.
Tubular secretion
Can be transcellular or paracellular.
Some substances are too larger or bound to proteins so cannot be filtered in glomerulus.
Pumps in the proximal tubule bring compounds into nephron from plasma:
- Organic acid and drug pump
- Organic base or drug pump
