Hormones Flashcards
What is the definition of a hormone?
A regulatory substance produced in an organism and transported in tissue fluids such as blood to stimulate specific cells or tissues into action. Chemical messenger- stimulates specific cells or tissues.
Describe water soluble hormones?
*binding to extracellular receptors
* freely transported in the blood
*cannot diffuse through bilayer, must bind to the receptor which will then open channel proteins to allow the transport into the cell.
*Exert their effects through an intracellular second messenger that is activated when a hormone binds to a
membrane receptor
Describe lipid soluble hormones?
- Diffuse through and bind to intracellular receptors
- Need binding protein for transport- usually polar
- Pass through the membrane via diffusion
- Diffuse into the cell, where they bind to intracellular receptors. migrate to the nucleus, and activate specific target sequences of DNA.
Where is ADH produced?
Hypothalamus.
Where is aldosterone produced?
Adrenal glands
Angiotensin II is produced where?
Liver.
Erythropoietin is produced where?
Erythropoietin is produced by interstitial fibroblasts in
the kidney in close association with peritubular capillary and proximal convoluted tubule.
Renin is produced where?
Glomerular cells of kidneys.
What does EPO do?
. Erythropoietin stimulates the production of new RBCs inthe bone marrow
. A common consequence of renal failure ¡s reduced EPO, leading to reduced PCV, therefore non
regenerative anaemia.
Why might the kidney be particularly vulnerable to ischaemic damage?
Because renal arteries are end arteries, so have no anastomosis between them, so if one vessel is cut off/blocked, the part of the kidney it is supplying will not receive enough blood.
The kidneys’ vulnerability is also attributed to their being a major recipient of cardiac output, having a
high level of metabolic activity, the complexity of multiple enzyme pathways, actions of biotransformation enzymes, intricate endothelial cell transport, a large capacity for
reabsorption, and a high oxygen (02) consumption of the outer medulla.
Why are older cats more susceptible to renal disease?
*over time nephrons stop functioning and reserve nephrons take over. At some point all nephrons that can function are functioning and no reserve can take over. Because of the system of reserve nephrons, there are no signs of kidney insufficiency until the damage is really significant. When two thirds of the nephrons are lost the kidneys will no longer be able to conserve water, and the cat will pass larger amounts of dilute urine. By the time that the creatinine levels are elevated on a cat’s bloodwork, 75 percent of nephrons in both kidneys are gone.
