8194100
Descrição
FlashCards por Louise Mason, atualizado more than 1 year ago
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Criado por Louise Mason
mais de 7 anos atrás
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| Questão | Responda |
| What are the two consequences of an increases in osmolarity of the extracellular fluid? | dehydration and thirst |
| What hormone is released from the posterior pituitary in response to plasma omsolarity changes? | Antidiuretic Hormone/Vasopressin |
| How is a rise in plasma osmolarity detected? | by osmoreceptors in the hypothalamus |
| What action do osmoreceptors take to respond to osmolarity changes? | regulate the release of ADH from neuroendocrine cells, which is stored in vesicles to be released from the posterior pituitary as needed |
| What effect does excess fluid have on body fluid osmolarity? | lowers body fluid osmolarity by diluting solutes in plasms |
| At normal plasma osmolarity, is there any ADH in the blood? | yes, allowing a response to increases and decreases in body fluid osmolarity |
| What effect will an increase in osmolarity have on level of ADH? | increases circulating levels of ADH and increases water reabsorption |
| What effect will a decreases in osmolarity have on circulating levels of ADH? | decreases levels of ADH and so decreases water reabsorption |
| What effect does an increases in ADH have on urine production? | prevents the excretion of urine |
| What part of the nephron does ADH have an effect on? | distal tubules and collecting duct |
| What other change within the body can stimulate the release of ADH? | a decrease in blood pressure increases ADH secretion |
| How does an increase in ADH work to return blood pressure to normal levels? | increases water reabsorption to reduce the osmolarity to restore blood pressure |
| At what percentage decrease of blood pressure does it become a strong stimulus for ADH secretion? | a decrease by over 10% |
| Which factor, osmolarity changes and blood pressure changes, acts as a more effective stimulus for ADH response? | osmolarity changes |
| At levels that are higher than needed to concentrate urine, what effect does ADH also have? | acts as a vasoconstrictor to increase blood pressure at its maximum secretion |
| What two factors together allow the ECF to be diluted to lower osmolarity? | conservation of water and the same solute excretion levels |
| What does a change in ADH levels actually affect on a cellular structure level? | the number of aquaporins expressed on the cell membrane (increases or decreases this amount) |
| What time frame does ADH respond within to changes in osmolarity? | within minutes |
| What is the half life for ADH within the blood? | 15 minutes |
| What happens to the ADH to be removed from circulation? | removed by the kidneys or metabolised to allow further responses to be carried out |
| What substance found in cigarettes affects ADH release? | Nicotine increases ADH release (like morphine) |
| How does diabetes insipidus affect ADH release? | Central: removes control over osmolarity changes and so affects the production of ADH Nephrogenic: receptors to ADH are not present on the collecting ducts so there is no renal response |
| What is the most important extracellular ion in terms of regulation of osmolarity? | Sodium |
| What system would be affected if total Sodium levels weren't regulated but osmolarity was maintained? | Cardiovascular system; total body fluid might increase which would increase the strain on the CVS |
| What percentage of the ECF osmolarity is made up by Sodium ions? | 94% |
| What Sodium levels must be equalised to maintain a stable ECF volume? | amount of Sodium ingested and the losses from the body |
| What is the only body fluid that can be acted upon to regulate the volume and composition of ECF? | plasma |
| What hormone is the most important determinant of renal Na+ reabsorption? | Aldosterone |
| Where is Aldosterone produced? | in the adrenal cortex (result of angiotensin II) |
| What effect does Aldosterone have? | stimulates the Na+ reabsorption in the distal parts of the nephron |
| What ions does Aldosterone promote the secretion of? | H+ and K+ via H+K+ATPase |
| Besides from the distal tubule and collecting ducts, where else does Aldosterone promote Na+ reabsorption from? | colon, gastric glands and sweat glands |
| What overall effect does Aldosterone have on body fluid volume? | increases body fluid volume |
| What change in ionic composition of the plasma stimulates Aldosterone release? | increase in K+ |
| What are the two most important changes within the body that stimulate Aldosterone release? | change in plasma K+ concentration and a decrease in effective circulatory volume |
| Via what system does a decrease in effective circulatory volume lead to an increase in Aldosterone levels? | renin-angiotensin system |
| What enzyme is produced by the juxtaglomerular apparatus when body Na+ is reduced? | Renin |
| What change in arterial blood pressure also induces the release of renin? | a fall in arterial blood pressure |
| What effect does Angiotensin II have on reabsorption? | increases tubular reabsorption of salt and water |
| How can sympathetic activity have an effect on Angiotensin II? | an increase in activity leads to an increase in renin release (more angiotensin II and so aldosterone) |
| Angiotensin II prioritises the perfusion of which organs? | the brain and the heart |
| What action does Angiotensin II have on afferent and efferent arterioles? | constricts arterioles to reduce renal blood flow |
| How does arteriolar constriction lead to increased reabsorption? | the reduction in renal blood flow increases the oncotic pressure in blood leaving the glomerular capillaries and so favours water and salt reabsorption |
| What is the only way in which Angiotensin II can actually increase Na+ content? | by stimulating Aldosterone |
| What enzyme, found in the endothelial cells of the lung, converts Angiotensin ! to Angiotensin II? | Angiotensin converting enzmye (ACE) |
| What treatment can be given for high blood pressure? | ACE inhibitors |
| What centre in the hypothalamus is also stimulated by Angiotensin II? | thirst centre to increase the body fluid intake |
| What substances are synthesised and released from cardiac atrial cells? | Atrial Natriuretic Peptides |
| What are ANP's released in response to? | released in response to atrial stretch/increased extracellular volume |
| What effect do ANP's have on Sodium and ECF volume? | inhibit Na+ reabsorption and increase Sodium excretion to reduce ECF volume and blood plasma |
| ANP's inhibit the production of which hormone involved in Sodium regulation? | Aldosterone |
| What action do ANP's have on afferent arterioles and what effect does this have in the kidney? | vasodilation of afferent arterioles and increase the glomerular filtration rate |
| Which ionic exchange is increased by Angiotensin II and where does this take place? | Na+/H+ exchange in the proximal tubule |
| How does Angiotensin II affect the GFR? | reduces the GFR |
| What effect does an increase in sympathetic activity have on Sodium filtration? | decreases filtration |
| Where in the nephron do osmotic diuretics act on? | proximal tubule to decrease reabsorption |
| What do Thiazide diuretics do and where do they have an effect within the nephron? | block Na+ transporters in the distal tubule |
| What do Loop diuretics do? | inhibit Na+ re-uptake in the ascending limbs of the LoH, which reduces the gradient needed for Sodium reabsorption |
| Where in the nephron do K+ sparing diuretics and Na+ channel blockers have an effect? | in the collecting duct |
| What hormone is produced in the kidney that stimulates red blood cell production? | erythropoetin |
| What is micturition? | urination |
| How does urine composition change once it leaves the renal pelvis? | it doesn't - only in horses where mucus secretion in the ureter makes the urine slightly viscous |
| How is urine transported from the kidneys to the bladder? | moves as boluses via peristaltic contraction of smooth muscle |
| What sphincter is involuntarily controlled and keeps the entrance to the urethra closed? | the internal sphincter |
| What autonomic activity causes the internal sphincter to remain closed? | tonic sympathetic activity |
| What form of innervation is responsible for keeping the external sphincter closed? | tonic somatic activity |
| How is a change in bladder volume detected? | stretch-sensitive receptors in the walls of the bladder detect this |
| What happens to sensory neurones as the bladder fills? | an increase in pressure within the bladder causes an increase in activity of the sensory neurones |
| What does an increase in parasympathetic activity have within the bladder? | detrusor muscle contracts, bladder pressure increases, increased contractions, increased pressure etc |
| As the contractions and pressure in the bladder increases, what eventually happens? | decrease in somatic activity to the external sphincter, sphincter opens and the neck of the bladder dilates |
| What is reflex emptying of the bladder an example of? | positive feedback |
| What does urine flow out of the bladder stimulate? | stimulates urethra sensory cells to increase parasympathetic activity to the bladder muscles to allow complete emptying |
| Where in the brain does voluntary suppression of urination originate from? | cerebral cortex |
| In newborn and untrained animals, what is urination a result of? | urination is the result of a spinal reflex, which is determined by the amount of urine in the bladder at any given time |
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