lecture 1 Flashcards
what are the characteristics of living things
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metabolism
responsiveness
movement
communication
growth
reproductive
differentiation
define homeostasis
is the balancing of the internal conditions within the body, when faced with external/internal stimuli
what is homeostasis maintained by?
the regulation of chemical composition of extracellular + intracellular fluid
3 main components of the feedback loop
- receptor- detects stimuli, sends input
- control centre- decides action based on input, sends output
effector- response to reverse/amplify stimuli
describe neg. feedback loop
e.g. blood pressure, insulin, blood gluocse
response is to REVERSE
describe the feedback loop of blood pressure
blood pressure- stimuli detected, baroreceptors in certain blood vessels, sends nerve impulses to control centre (brain), sends nerve impulses to effectors- heart + blood vessels = creates a response by decreasing heart rate + dilation (widening) of blood vessels, cause blood pressure to decrease- returns to homeostasis
describe the feedback loop of blood glucose
stimuli- rising blood glucose level detected by g protein coupled receptors, causes beta cells of pancreas to release insulin into blood, makes body cells take up more glucose + liver takes up glucose and stores it as glycogen
causes blood glucose to decreases back to homeostasis
if blood glucose decreases (e.g. skipped a meal), causes alpha cells of pancreas to release glycagon into blood, causes liver to break down glycogen + release glucose into blood, causes blood glucose level to rise, back to homeostasis
describe positive feedback loop
e.g. labour contractions during birth
response is to AMPLIFY
describe the feedback loop of labour
stimuli- contractions of the wall so f the uterus, forcing the baby out, stretch sensitive receptors in nerve cells of cervix send impulses to control entre (brain), brains interprets + releases oxytocin (from pituitary gland), causes effectors (muscles in walls of uterus), to contract MORE forcefully, causing cervix to stretch allowing baby to be removed
cytosol vs cytoplasm
cytosol- is the liquid
cytoplasm- liquid +organelles
what is the function of the membrane
seperate inside/outside cell
transport
communication
permeability vs impermeable vs selective
permeability- is the passage of substances across the membrane
impermeable- cant
selective- permits some
what does selective permeability depend on
-membrane solubility characteristics (e.g. hydrophobic vs hydrophilic)
-presence of integral transport protein
polar vs non-polar
polar: molecules tat are slightly pos./neg. on each side, asymmetric
non-polar: symmetrical
what is the membrane composed of?
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cholesterol, phospholipids, carbs, proteins
C+P = lipid bilayer
P+C = glycolipids
C+P = glycoproteins
glycolipids + glycoproteins = function = cell structure, cell communication, immune response
