communication and homeostasis
homeostasis
the maintenance of a stable equilibrium of the conditions inside the body
internal environments must be kept consistent so metabolic processes can function correctly
internal environment
blood glucose conc
temp
water potential
cell pH
external environment
humidity
temp
light intensity
sound
why do organisms need communication systems
so the signsl can be interpreted and the correct response is triggered
negative feedback
a small change in one direction detected by sensory receptors
effectors work to reverse the inital change and restore conditons
e.g. effect of insulin and glucagon on blood glucose conc
positive feedback
a change in the internal environment of the body is detected by sensory receptors
effectors are stimulated to reinforce the change and increase the response
e.g. oxytocin levels during childbirth
ectotherm (cold-blooded)
core body temp is dependent on their environment
invertebrates, fish, amphibians, reptiles
aquatic organisms- no need to regulate body temp due to high specific heat capacity water
land organisms- adapt to changes in temp
ectotherms adaptations
behavioural- basking in the sun, spread wings to maximise SA
physiological- darker skin colours increase heat absorption
endotherm
regulate their body temp at 37 degrees
hypothalamus and peripheral temp receptors monitor body temp
behavioural adaptations- basking in sun, hibernation
endotherm- vasodilation
opening of arteries
when temp is high arterioles near surface dilate and more blood goes to capillaries near surface
causes energy to be transferred out to surroundings
shunt vessel is constricted
endotherm- vasoconstriction
restriction of arteries
arterioles constrict, reducing blood flow to surface so less energy is lost by radiation
shunt vessels are open
how do these effect body temp?
sweat glands- secretes sweat onto skin, transfers energy away from skin, water evapourates
lungs, mouth, nose- removes heat by breathing out warm air and in cool air, water vapour->evapouration
skin hairs- erector pili muscles cause hairs to stand up trapping a layer of warm air
liver calls- highly metabolically active so release lots of heat
skeletal muscles- involuntary muscle contraction (shivering), releases heat by respiration
excretion
removal of metabolic waste
e.g. co2 during respiration excreted by lungs
bile pigments excreted into small intestine
urea, formed by breakdown of excess amino acids excreted by kidney
liver blood vessels
hepatic artery- branch of aorta, provides oxygenated blood
hepatic vein- blood from liver to vena cava
hepatic portal vein- carries products of digestion from small intestine to liver
cells in liver
hepatocytes
large nucleus
prominent golgi apparatus
many mitochondria
hepatocytes
arranged in narrow rows along 2 sets of canals (sinusoids and canaliculi)
sinusoids
1 set of canal
carry blood from hepatic artery and hepatic portal vein to central vein (branch of hepatic vein)
lined with macrophages called kupffer cells (quick acting and protect liver from infection)
canaliculi
2nd set of canals
carry bile produced by hepatocuree to branches of bile duct around outside of liver lobule
carbohydrate metabolism
deanimation
detoxification
deanimation
animo acids are either transaminated or deaminated
transamination- amino acid converted into different amino acid by changing R group
demination- removal of amine group, amine group converted to highly toxic urea and excreted via kidney
production of urea is done by ornithine cycle
deamination of excess amino acids
forms ammonia
product- urea
detoxification
hydrogen peroxide is converted to water and oxygen by enzyme catalase
liver also breaks down alcohol into ethanal and then ethanoate
3 areas of kidney
renal cortex
renal medulla
renal pelvis
renal artery branches from aorta provides blood to kidney, renal vein takes blood away from kidney and joins vena cava
ureters carry urine to bladder
functional unit of the kidney
nephron
as blood passes along nephron a number of changes occur
1. blood is filtered removing waste products and many useful molecules
2. majority of useful molecules pass back from kidney into blood
3. water and mineral ions are balanced
4. waste products are passed into ureter
order of kidney
afferent arteriole
glomerulus + bowmans capsule
efferent arteriole
proximal convoluted tubule
vasa recta + loop of henle
distal convoluted tubule
collecting duct
cortex or medulla
vasa recta
loop of henle
bottom of collecting duct
all in medulla
rest in cortex
bowmans capsule
where blood is ultrafiltered
removing all waste products and many other useful products
proximal convoluted tubule
site of selective reabsorption
loop of henle
where majority of water and salrs are reabsorbed into blood
ultrafiltration
where dissolved substances and water are forced from blood into lumen of bowmans capsule
glomerulus- loops of capillaries, efferent arteriole is narrower than afferent, blood under high pressure
impact of higher pressure is to force the maximum amount of dissolved substances through the walls (urinary space)
to move from glomerular capillary into lumen of bowmans capsule, substances mist pass through 3 layers
endothelial wall
basement membrane
podocytes
endothelial wall
capillary wall with more and bigger gaps, making glomerular capillaries more leaky than other capillaries
basement membrane
network of proteins
determines maximum size of molecule that can move through into urinary space
large proteins are prevented, max size is 69000 molecular mass
podocytes
wall of bowmans capsule made up of epithelial cells
pedicels wrap around capillary forming slits, slits allow glucose, salt, urea to pass into urinsry space
selective reabsorption
proximal convoluted tubule have microvilli, gives large surface area, also have large number of mitochondria for active transport
mechanisms include active transport, faciliated diffusion and simple diffusion
selective reabsorption process
1. sodium ions are actively transported out if pct cells and diffuse into blood
2. sodium ions move down via conc gradient and enter pct cells via co-transporters, transported with glucose, amino acids, vitamins, chloride ions
3. co-transported substances then leave pct cells via channels on basal side
4. they are transported away in blood, movement of these substances changes the solute potential of pct cells, water will follow by osmosis
urea
in high conc in pct lumen
creates huge conc gradient between lumen and blood
osmoregulation
loop of henle
distal convoluted tubule
collecting duct
loop of henle
urine is concentrated by removal of water and balancing of dissolved sodium and chloride ions
limbs run in opposite directions and act as countercurrent multiplier
top of ascending limb
sodium and chloride ions are in similar concs inside and outside
sodium and chloride ions are actively pumped out of kidney tubule
this produces very high osmotic gradient
ascending limb is impermeable to water so osmosis cannot follow so ions arent lost in urine
bottom of ascending limb
conc of sodium and chloride ions in kidney tubule is high and theres a steep gradient
this part of loop is permeable to sodium and chloride ions but not water
descending limb
upper part is impermeable to water so contents move down into lower region
surround tissue is filled with sodium ans chloride ions so theres large osmotic gradient
water moves out of descending limb into surrounding tissure fluid
impermeable to sodium and chloride ions- fluid that reaches hairpin bend is very concentrated of urea and sodium and chloride ions
distal convoluted tubule
balances the salt in the body
if body lacks salt, sodium ions are actively pumped out of dct, chloride ions follow down electrochemical gradient
collecting duct
has high solute potential, creates laege osmotic gradient for water
permeability is determined by antidiuretic hormone (adh)
if blood becomes too concentrated adh is released
adh
1. binds to receptors on plasma membrane
2. inititates enzyme controlled reactions
3. vesicles containing water permeable channels (aquaporins) fuse to membrane
4. more water can be reabsorbed
reasons for kidney failure
infections
high blood pressure
genetic condition
symptoms of kidney failure
loss of osmotic balance
build up of urea
high blood pressure
weakened bones
painful joints
anaemia
glomerular filtration rate is measured by creatine levels in the blood
haemodialysis
arterial blood flowing into dialysis machine and between dialysis membranes
membranes mimic basement membrane
dialysis fluid flows on opposite side in countercurrent direction and is carefully balanced to faciliate diffusion of urea
peritoneal dialysis
inside the body
dialysis fluid is put into the abdomen, left for several hours which allows urea and excess mineral ions to diffuse out
dialysis fluid is then drained out and discarded
kidney transplants
cures kidney failure
new kidney is attached to arteries and veins and ureter to bladder
kidney selected to match tissue type and blood group
patients take immunosuppressant drugs (side effects)
urine analysis (pregnancy test)
1. hCG hormone from urine
2. mobile hCG monoclonal antibody attached to dye, hCG binds to antibody
3. immobile hCG monoclonal antibody binds
4. excess mobile hCG antibodies bind to immobile amtibodies
pregnancy test
blue line indicates high conc of monoclonal antibody with dye attached
if blue line is in both windows, hCG is in their urine and are pregnant
if blue line is only present in 2nd window, test worked but not pregnant
if no blue line in 2nd, test failed