Homeostatis Flashcards
homeostasis
the ability of an organism to maintain a constant internal environment
what is thermoregulation
the control of the internal body temperature.
why do organisms heat up and cool down
Exo chemical reactants
Latent heat of evaporation
Radiation
Convection
Conduction
what are ectotherms
Use their surroundings to warm their bodies
Core body temperature is dependent on environment
Live in water and don’t need to thermoregulate
High heat capacity means temp of environment does not change
endotherms
Endotherms:
Rely on their metabolic processes to warm up and they usually maintain a stable core body temperature
Have adaptations which enable them to maintain their body temperature and take advantage of warmth from the environment
Metabolic rate is higher than ectotherms.
which one, ednotherms or ectothers cannot control body temp and how have they overcome this
ectotherms
they have overcome this by behavuoural and physiological responses
examples of behavioural response
Bask in the sun, orientating their bodies so that maximum surface area is exposed towards the sun
Through conduction, they can increase their body temperature by pressing their bodies against the warm ground.
Cool down by preventing their core temperature reaching a point where enzymes begin to denature
To cool down they shelter from the sun by seeking shade or hiding
physiological response
Dark colours absorb more radiation than light
Alter their heart rate to increase or decrease the metabolic rate and to affect the warming or cooling across the body surfaces
What detects temperature of the blood in the body surfaces?
Temperature receptors in the hypthalamus
waya to cool down
- vasodilation
- increased sweating
- reducing insulating layers of hair or feathers
explain vasodilation
arterioles constrict
less blood able to flow
minimises heat which can radiate
increasing sweat
sweat glands reduce secretion of sweat
reducing insulating effect of hair or feathers
hair erector muscles relax
hiar lie flat
avoids trapping insulating layer
ways to warm up
Vasoconstriction
Decreased sweating
Rasing body hair or feathers
Shivering
vasoconstriction
arterioles constrict
atriovenous shunt vessels dilate
little blood flow
little radiation takes place
decreased sweating
core temp falls
sweating decrease
sweat production stops
reduces cooling
raising body hair
erector pili misicles contract
traps insulin layer
shivering
muscles contract
what are the 2 control centres to control thermolregulation in the hypothalamus
heat loss
heat gain centre
heat loss centre
Activated when the temperature of the blood flowing through the hypothalamus increases, sends impulses through autonomic motor neurons to effectors triggering response to lower core temperature
heat gain centre
Activated when the temperature of the blood flow through the hypothalamus decreases, it sends impulses through the autonomic nervous system to effectors in the skin and muscles which triggers responses that act to raise the core temp.
what is excretion
removal of waste products pf metabolism from the body
what are the main metabolic waste products in mammals
co2
bile bigments
nitrogenous waste (urea)
function of the liver
- breaks down amino acid into urea
- detoxfies the blood
- stores glycogen
- makes bile
structure of the liver
hepatic artery
hepatic vein
hepatic portal vein
bile duct
hepatocytes
liver lobules
sinusoids
kuppfer cells
function of the hepatic artery
to deliver oxygenated blood to the liver
aorta——liver
function of the hepatic vein
take deoxygenated blood away from the liver, allows amino acids to enter
liver —- heart
function of the hepatic portal vein
allows harmful substances to be removed from liver and broken down
intestine — liver
function of the bile duct
takes bile from liver to the gall bladder
liver lobules and hepatocytes
specialised epithelial cells which is made up of hepatocytes which divide and replicate
what connects the hepatic artery and hepatic portal vein
sinusoids
what converts toxic substances into less harmful substances
blood moves through sinusoids and hepatocytes convert
what are kupfer cells
attach to walls of sinusioids and break down red bloood cells and remove bacteria
carbohydrate metabolisim
bgc levels increase
insulin rise
hepatocytes stimulated to convert glucose into glycogen
deamination
amino group removed from an amino acid and ammonia and organic ions are produced
reaction of liver converting amino acids into urea
ornithine cycle
detoxification
the liver detoxifies harmful toxins and make them harmless
what is the 2 important roles of the kidney
osmoregulation
excretion
they filter nitrogenous waste products out of the blood, urea
they maintain the water balance and PH of the blood and hence the tissue fluid which surrounds all the cells
production and release of urine
nephrons act as a filtering unit and the liquid produced by the kidney tubules is urine
urine passes out the kidneys down ureters and is collected in the bladder, the sphincter opens the bladder and urine passes out down the urethra
Main 3 areas of a kidney
cortex
medulla
pelvis
cortex
dark outer layer
filter of blood
capillary network which carries blood from renal artery to nephron
medulla
light colour
tubules of nephron which forms pyramids of kidney and cd
pelvis
where urine is collected
Nephron
filters blood, removes nitrogenous wastes and balances mineral ions and water
structure of nephron:
Bowmans capsule
contains glomerulus, more blood goes in than leaves due to ultrafiltration
structure of nephron:
proximal convoluted tubule
found in cortex
coiled region after the bowman’s capsule
covered with microvilli to increase SA
many mitochondria to provide ATP
GLUCOSE, AMINOACIDS, VITAMINS, HORMONES move from filtrate back into blood via active transport
structure of nephron:
loop of Henle
creates region of high solute conc in tissue fluid in the medulla
broken down into:
ascending limb which is medulla to cortex
descending limb which is the context to medulla
structure of nephron
Distal convoluted tubule
ADH
structure of nephron:
collecting duct
urine passes down cd through medulla to pelvis
ultrafiltration
to remove nitrogenous waste and osmoregulation of the blood
where does ultrafiltration take place and process
Bowmans capsule
- blood enters through the afferent arterioles which splits into capillaries forming the glomerulus, this causes a high hydrostatic pressures of the blood.
- small molecules such as water urea etc are forced out which forms glomerulus filtrate.
- fluid passes through the basement membrane which along with the capillary acts as sieve
- podocytes within the Bowmans capsule act as an additional filter.
what is the process of selective reabsorption
In the proximal convoluted tubule (PCT), loop of Henle and the distal convoluted tubule (DCT), useful substances are reabsorbed, passing out of the nephron and back into the capillaries. Glucose is reabsorbed in the PCT by active transport and facilitated diffusion. Water is reabsorbed in the loop of Henle, DCT and collecting duct by osmosis. The remaining filtrate is urine, containing excess water, excess salts and urea. This passes from the collecting duct to the bladder via the ureter.
what is the adaptations of the pct
many mitochondria to provide atp
and many microvilli to increase sa
loop of Henle process to control the movement of ions and allow water to be reabsorbed.
The ascending limb is permeable to ions but impermeable to water, sodium ions are actively pumped into the medulla.
This lowers the water potential of the medulla, causing water to move out of the nephron by osmosis from the descending limb (which is permeable to water but not ions).
As water moves out of the nephron, the filtrate becomes more concentrated. This causes sodium ions to move out of the nephron at the start of the ascending limb, down their concentration gradient by facilitated diffusion.
This lowers the water potential of the medulla even further, causing water to move out of the DCT and collecting duct by osmosis.
Water that has moved into the medulla eventually moves into the capillary
dct
balances the water needs of the body
many mitochondria to carry out active transport
cd
urine
function of adh
controls water content of our urine by increasing the reabsorption of water from cd
negative feedback mechanism of adh
Osmoreceptors in the hypothalamus detect a drop in blood water potential.
The hypothalamus signals to the posterior pituitary gland to secrete ADH.
ADH causes the walls of the DCT and collecting duct to become more permeable to water (by the incorporation of more aquaporins into the membranes of the cells that line these parts of the nephron).
More water moves by osmosis out of the DCT/collecting duct and reabsorbed into the bloodstream, increasing its water potential.
A smaller volume of concentrated urine is produced.
mechanisim of adh action
- vesicles in cell lining of the collecting duct fuse with cell surface membranes of medulla
- membranes contain aquaporins which make it more permeable to water
- this allows water to move out of the tubule cells into blood capillary via osmosis
go over urine and testing
kidney failures
