Kidney Flashcards
Homeostasis
Maintenance of a constant internal state
Control system
Sensor
Having a sensor (receptor) that monitors the factor being controlled (by providing info for the monitoring of the factor being controlled)- can be in the brain or localised throughout he body- control centre usually in the brain
Control system
Corrective mechanism
Brings about changes resulting in regulation of this factor
- receptors show a departure from normal levels (the set point) the. A corrective mechanism brings about he changes required to return it to normal
Mammals overheat, sweating or vasodilation of capillaries in skin
Control system
Negative feed back system
Stops the corrective mechanism and prevents over correction- corrective mechanism involves negative feedback, causes corrective measure to turn off as factor being controlled is returned to normal level. Prevents over correction.
Why homeostasis control of mammalian body essential
- providing optimum conditions for enzyme reactions in terms of pH and temp
- avoiding osmotic problems in cells and in body fluids
Two imports fundtions of Kinsey
Excretion ( removal of toxic waste products of metabolism) (urea and creatine) and osmoregulation (maintenance optimal water potential of body fluids)
Kidney and nephron funstion involves two main processes
Ultrafiltration and readsorption
Ultrafiltration
The filtration ofnplasma and substances below a certain size into the bowl and capsule (nephron)
Readsorption
As ultrafiltration is based purely on molecular size or not whether products are useful or not it is essential that filtered useful products are selectively reabsorbed back into the bloodstream from the nephron
Why does blood entering the glomerulus have a high hydrostatic pressure
Short distance from the heart that the blood travels down the aorta and into the renal aretery before branching into the kidney arteriols
Afferent arterial is wider than its efferent
Cooling of capillaries in glomerulus restricts blood flow therefore inc pressure
Affarent arteriols vs efferent
Wider in diameter
Main driving force for ultra filtration
High blood pressure within glomerular capillaries
Opposes blood pressure
Osmotic gradient from the filtrate in the nephron into the glomerula capillaries
Back pressurenif the filtratebin the nephron
Active transport of what in PCT
Glucose, amino acids and salts from filtrate to the epithelial cells to the capillaries if the vasa texts system
How osmotic gradient created
Lowering of solute potential in the cuboidal epithelium and the blood capillaries
Responsible for bulk of water readsorbed
