The Urinary System - Part 1 (week 10) Flashcards
state 4 methods of treating hypertension (high blood pressure)
- diuretics
- beta-adrenergic receptor blockers
- calcium ion channel blockers
- angiotensin-converting enzyme (ACE) inhibitors
explain how diuretics can help reduce blood pressure / treat hypertension
diuretics increase the excretion of Na+ and H2O, decreasing cardiac output with no change in peripheral resistance
explain how beta adrenergic receptor blockers can help reduce blood pressure / treat hypertension
reduce cardiac output by blocking the binding site for norepinephrine / epinephrine
explain how calcium ion channel blockers can help reduce blood pressure / treat hypertension
reduce entry of calcium ions (Ca2+) into vascular muscle cells = weaker contractions = lower peripheral resistance
explain how angiotensin-converting enzyme (ACE) inhibitors can help reduce blood pressure / treat hypertension
the final step in the formation of angiotensin 2 (a vasoconstrictor) is mediated by an ACE. blocking this enzyme causes vasodilation, lowering blood pressure
explain the role of aldosterone of in the renin-angiotensin system
aldosterone is a slow acting steroid hormone that stimulates Na+ reabsorption by the kidney tubules
explain the role of vasopressin (ADH) in the renin-angiotensin system
rapid acting peptide hormone, produced by the hypothalamus and secreted by the posterior pituitary gland, which stimulates water reabsorption
explain the role of angiotensin-converting enzymes (ACE) in the renin-angiotensin system
they are found on endothelial cells and mediate the final step of angiotensin 2 production (a vasoconstrictor)
explain the role of the intra-renal baroreceptors in the renin-angiotensin system
intra-renal baroreceptors detect changes in stretching which is proportional to changes in blood volume which stimulates a change in the production of renin
what do cardiac cells produce which is used in the renin-angiotensin system
atrial natriuretic peptide (ANP)
state the 3 functions of atrial natriuretic peptide (ANP) in the renin-angiotensin system
- inhibits Na+ reabsorption by the kidney tubule cells
- acts on renal blood vessels to increase filtration rate causing Na+ excretion
- inhibits the action of aldosterone
state what it is meant by the key term - Renin
Renin is an enzyme produced by the juxtaglomerular cells, secreted, and stored in the kidneys, which promotes the production of the hormone Angiotensin
state what occurs within hours of blood loss (4 points)
- compensatory movement of interstitial fluid into the capillaries to increase plasma volume (redistribution)
- an increase in thirst (slower)
- a decrease in Na+ and H2O secretion (slower)
- mediated by hormones (renin, angiotensin, aldosterone) and kidney function
state what occurs within days of blood loss (2 things)
- erythropoiesis
2. haematopoiesis
what is the normal human body core resting temperature? and what is the normal range?
- 36.5 - 37.5 degrees
2. 35 - 39 degrees
what proportion of energy from food is lost from the body as heat?
2/3 of all energy liberated from food is lost as heat
what is the value of heat produced by the average body at rest?
1.25 - 1.5 kcal/min
what is the value of heat produced by the average body during exercise?
15 - 20 kcal/min
state the 5 sources of heat gain
- solar radiation
- thermal radiation
- convection
- metabolic heat production
- conduction
state the 5 sources of heat loss
- radiation
- convection
- respiratory evaporation
- conduction
- sweat evaporation
state the 4 values of heat loss at rest, in ambient environmental conditions
(i.e. radiation, convective air currents, conduction and evaporation)
- radiation - 60%
- convective air currents - 12%
- conduction (eg - feet to floor) - 3%
- evaporation (lungs + skin) - 25%
what percentage of heat loss can be lost from evaporation from the skin during exercise?
80% of heat loss can occur via evaporation from the skin during exercise (dependent on humidity)
state the kidneys role in water and electrolyte balance
the kidney cannot restore a body water deficit, but can help to preserve body water and electrolytes during periods of increased loss