Unit 4 Flashcards
What are the two fluid compartments of the body and what do they contain?
Intracellular – within the cells
Extracellular – tissue, plasma, lymph, transcellular fluid
Total body water is contained
What is the ratio of body fluids?
Intracellular = 2/3 Extracellular = 1/3
If total body water amounts to 40L
25L= intra
15L = extra
What are the 7 functions of the kidney?
- maintenance of water balance
- maintenance of electrolyte balance
- maintenance of blood pH
- removal of wastes and toxins
- gluconeogenesis
- hormone production
- urine production
What is gluconeogenesis?
- Making glucose from non glucose
* During prolonged periods of fasting the kidneys make glucose from amino acids and other precursors (lactic acid)
What is the main function of the urinary system?
Control the internal environment of the body by controlling the composition of the blood.
Blood must always be in equilibrium with other body fluids
What hormones are produced directly by kidney?
Erythropoietin
• Stimulates red blood cell formation in red bone marrow
• Stimulus for production = decrease of oxygen in blood
• Encourages multipotent stem cells to become erythrocytes (RBC’s)
What is active vitamin D?
- Indirect hormone production
- Result of action of UV light against skin
- 2 hydroxyl groups are added by liver and kidney
- Results in molecule that stimulates absorption of calcium from GI tract
What is aldosterone?
- Indirect hormone secretion by adrenal gland in response to renin secreted in kidney during low bP.
- Renin = enzyme produced by kidney in response to decreased Bp
Summarise the aldosterone pathway (7 steps)
- low bP
- renin production (kidney)
- production of angiotensin 2
- aldosertone secretion (adrenal gland)
- inc absorption of Na+ & H20 in kidney tubules
- blood volume inc
- blood pressure inc (to normal)
What is a nephron?
The functional unit of the kidney, they do the kidneys job (filter blood and produce urine)
About 1 million per kidney
What are the main parts of the nephron?
- Renal corpuscle (consists of glomerulus and bowmans capsule)
- Proximal convoluted tubule
- Loop of henle
- Distal convoluted tubule (2-4 make up renal tubule)
- Collecting duct
What are the two layers of the bowmans capsule?
What is the bowmans space?
• Outer parietal layer
Inner visceral layer (in contact w glomerulus)
• The space between the parietal and visceral layers
What is the filtration barrier?
What is its function?
The barrier between the blood flowing through the glomerulus and the filtrate in the bowmans capsule.
Filters water and small solutes from blood plasma into renal tubule as the 1st step in urine production. Large molecules not filtered, remain in blood
What are the 3 layers of the filtration barrier?
- glomerular capillary endothelium
- basement membrane of glomerulus
- epithelium of visceral layer of bowmans capsule
What is the difference between the glomerulus and normal capillaries?
- Much longer, larger surface area
* More permeable so has higher rate of filtration
What is the function of the renal tubule and what are the 3 main parts?
What is the collecting duct function?
Function: reabsorption and secretion of substances
- PCT
- nephron loop/loop of henle
- DCT
Receive filtrate from many nephrons
What are the 3 protective layers of the kidney?
- renal capsule
- adipose capsule
- renal fascia
What are the two capillary networks in the nephron?
- glomerulus
- peritubular capillaries/vasa recta
at all points the renal tubule is intimately associated with the peritubular capillary network to allow transfer of materials between peritubular blood and lumen of tubule.
What is the structure and function of juxtamedullary nephrons?
- make up 15% of nephrons
- longer loop of henle, extends to medulla (inner).
- has vasa recta (blood capillaries around loop)
- involved in concentrating and diluting urea
What is the hilus/hilum?
The indentation on one side of the kidney where the ureters and blood vessels enter and leave kidney
Blood supply is mainly to the cortex as that is where filtration occurs
What amount of cardiac output do kidneys receive?
Which vein /artery carries blood to and from the kidneys?
25% which is approx. 1200ml of blood per minute
Renal artery = into
Renal vein = away from