communication and homeostasis and hormonal com. Flashcards
what is the need for communication systems in multicelluar organisms
animals and plants must respond to changes in their environment both internal and external as enzyme controlled reactions can only take place if conditions are right eg) pH, ion conc, temp, water balance
> Organisms use chemical and electrical systems to monitor and respond to any changes and maintain DYNAMIC EQUILLIBRIUM
describe how communication between cells by cell signalling occurs
using receptors and effectors
>sensory receptors detect changes in the internal and external environments of an organism
>information from these sensory receptors is transmitted back to the brain and impulses sent along motor neurones to the effectors to restore equiliibrium
effectors can be muscles or glands that react to motor stimulus
what is the difference between receptors and effectors
A receptor detects the stimuli and converts it into an impulse and an effector converts the impulse into an action. An example of a receptor is a light receptor in the eye which detects changes in light in the environment. An example of an effector is a muscle.
what is a positive feedback
fewer positive feedback systems in body
examples like contractions during childbirth or the blood clotting cascade
receptor detects and effectors are stimulated to reinforce that change and increase the response
what is a negative feedback
majority of feedback in body is negative feedback
> small change detected by SENSORY receptors and effectors work to change and restore conditions
involved in temperature control and water balance
eg) increase detected»> responds lower levels»_space;>ideal conditions
ectotherms
what is their core body temp dependent on
their surroundings
fish, invertebrates, amphibians and reptiles (most animals)
why do ectotherms that live in water not need to regulate body temp?
-Due to higher heat capacity of water, the temperature of the environment doesn’t change much
why is it important ectotherms on land regulate temp?
- drastic seasonal and daily changes in temp (these can increase or reduce radiation they absorb from sun)
- need to warm up to carry out metabolic reactions that happen fast enough to be active.
eg) lizard in sun warm up to catch prey fast
How do ectotherms increase body temp by conduction
press body against warm ground
give an example of how ectotherms use exothermic metabolic reactions to warm up
Galapagos lizards contract muscles and vibrate which increases cell metabolism to raise body temps
-butterflies and moths also do this
how do ectotherms cool down and why
opposite to warming up processes
- must cool down to prevent core body temp being too high resulting in denaturation of enzymes
- shelter from sun in cracks in rocks, digging
- press body against cool earth, stones or nearby water and mud
- orientate to minimise surface area in sun
What physiological adaptations do ectotherms have
- dark colours absorb more radiation (lizards in cold are darker vice versa)
- alter heart rate to increase/decrease metabolism and effect of warming and cooling on their surface
are ectotherms or endotherms more vulnerable to changes in environment
ectotherms- adapted for conditions
why do ectotherms need less food
they use less energy regulating body temps, therefore can survive in places food is in short supply eg deserts
What factors are effecting the external environment of an organism
temperature, pH, light intensity
water availability, oxygen availability
threats, sounds, pain
What factors are effecting the internal environment of an organism
blood glucose, internal temp, waste products like urea, hormone levels, osmoregulation, pH
what are the two communication systems in the body
nervous system- cells and neurones
endocrine system- hormones
go look at 5.1.1 communication + homeostasis flashcards in bio
gogogo
what is excretion
removal of metabolic waste from cells of body.
The removal of by-products or unwanted substances from normal cellular processes to maintain homeostasis
oh an go learn the liver and kidney one too
gogogoog
describe briefly the structure of the liver and look up a picture of it!!
i hope u have looked at a photo
section of the liver is called a
lobule
what are lobules lined with
hepatocytes
what is in the centre of the lobule
hepatic vein hepatic venule which joins to hepatic vein
what are sinusoids
passage for blood in liver (honeycomb like)
where is the bile made in the liver
canaliculus (lots of canaliculi) doesnt link to venule
bile drains into bile ductules which goes to the gall bladder
what are Kupffer cells
line sinusoid walls and described as fixed phagocytes (macrophage in phagocytosis)
get rid of worn out erythrocytes+leucocytes as haemoglobin has short life
what is bilirubin
pigment formed in the breakdown of haemoglobin and found in bile (makes faeces brown and lack of makes faeces white)
the hepatic artery….
carries oxygenated blood TO the liver from heart via aorta
the hepatic portal vein….
takes blood rich in products of digestion from intestines TO liver
the hepatic vein
rejoins vena cava takes deoxygenated blood out of liver
describe the ornithine cycle
the deamination of amino acids to ammonia and then to urea through enzyme controlled reactions in the ornithine cycle
remaining amino acids are used in cellular respiration or converted into lipids for storage
what is detoxification
-other metabollic pathways other than urea, produce potentially posionous substances and also things like alcohol and drugs by choice
»»liver detoxifies to make less harmful.
example of detoxification with hydrogen peroxide
catalase breaks down into oxygen and water
how does the liver detoxify alcohol
alcohol contains ethanol the active drug in drinks
-alcohol dehydrogenase breaks down ethanol to acetaldehyde and further into acetic acid and acetyl-CoA. whihc forms ethananoate (made from acetic acid) which builds up fatty acids or used in cellular respiration
what is the formula of urea
CO(NH2)2
what happens to the amine group of excess amino acids
- what and where does it take place
- what does it form
removed in excretion by deamination which takes place in the liver.
amine group joined with hydrogen to form ammonia NH3 and then into urea
how does the liver store glycogen
When blood sugar rises in the blood, insulin is released by the pancreas and travels through the blood. The insulin binds to receptor cells in the liver and receptor molecules on muscle cells, causing them to take in and store the excess glucose as glycogen.
by glycogenesis
opposite is glycogenolysis caused by glucacon and adrenaline
look at a diagram of the ornithine cycle
gogogoogooogo
what parts make up the kidney
cortex
medulla
pelvis
what does the cortex of the kidney do
outer layer
-where filtering takes place, very dense capillary network carrying blood from renal artery to nephrons
what is the function of the medulla of the kidney
contains tubules of nephrons that form pyramids of kidney and also the collecting ducts
appears lighter on micrographs
what is the function of the pelvis
(basin) central chamber urine collects in before going to urteter
where is blood filtered in kidney and what are they removing
the nephrons
- nitrogenous waste (urea)
- excess water
- excess ions
about 3cm long and there are 1.5 million in each of the kidneys
