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Detecting Environment/Signaling (odor (olfactory receptor neuron, odorant…
Detecting Environment/Signaling
Plants don’t have nervous systems but some do use electrical signals
sensory receptors
ionotropic
activated by
pressure
(pr sensitive ion channels)
activated by
warmth
(temp sensitive ion channels)
proteins associated with ion channels
voltage-gated
metabotropic
response not directly on channel, metabolic pathways
taste/smell
Na+ or K+ channels
light
cGMP-gated Na+ channels
receptor, G protein, effector molecule, channel
odor
olfactory receptor neuron
odorant molecule binds- events that open
Na+ channels
, cause action potential
attach to
cilia
one cell cant detect all
each cell ending on
glomerulus
light detection
photoreceptor cell
activated G protein- cascade of events that alter membrane potential and cause leaky
Na+ channels
to close
conformation change in func group on
rhodopsin
in retina of human
eye
ciliary muscle
ctrls thickness of lens for near (contracts-rounder) or distance (relaxes-flatter) vision
cornea
fovea
optic nerve
cells
rods
night/low light
cones
daytime/color
3 kinds- absorb diff wavelengths of light
how is detected
light passes through clear neurons to reach rods and cones in back of retina (pigmented)
clear neurons- ganglion, amacrine, bipolar, horizontal cells
visual info processed through cells and converge on ganglion cells
rods and cones>bipolar cells>ganglion cells
photoreceptor
naturally depolarized bc of leaky Na+ channels
become hyperpolarized w light, more w stronger light
dont fire action potentials
signaling in plants
detection of and response to light imp, involve pigments other than photosynthetic ones
types of light detected
blue
phototropism
bending towards light
cells elongate
at least 3 diff receptors
seedling elongation
after emergence from soil
stomatal opening
in response to light
solar tracking
red vs far red
phytochrome involved in
photoperiodism
detection of daylength
shade detection and avoidance
germination response
to increased light
photochrome
2 identical subunits
photoreceptor activity
kinase activity
chromophore
absorbs light and changes forms
2 isomeric forms
Pr
Pfr
cant absorb red light, only far red
ctrls seed germination
depends on ratio of r/fr light
Pr > red light > Pfr
night- slow conversion Pfr > Pr
indirect measure of day length
shade avoidance
detect shade
light passing through another plant has a reduced ratio of red/far red wavelengths > grow taller
Vertebrate Endocrine System
types of endocrine signaling
hormones
receptor on cell if water soluble, in cell if lipid soluble
multiple receptors / target cells > useful activities
paracrines
nearby cells
autocrines
influence same cells that produced signal
neurohormones
neurotransmitters involved in cell- cell signaling; some hormones associated w nerves
endocrine (extracellular fluid), exocrine (direct into a cavity or skin surface)
3 main groups of animal hormones
peptides and proteins
water soluble and thus can be transported in the blood wo carrier (are the largest)
steroid hormones
made from cholesterol; not water soluble; can pass through membranes via receptor but need carrier in blood
same basic building blocks; modified from cholesterol molecules
amine hormones
most made from amino acid tyrosine; some water soluble, some not
prolactin
same structure, diff func in diff organisms
locations
pituitary
interfaces b/w nervous and endocrine system
posterior pituitary
releases 2 neurohormones: ADH and oxytocin produced by hypothalamus; transported in axons
anterior pituitary
receives commands via neurohormones from hypothalamus through bl vessels then makes and secretes hormones
releases
4 tropic hormones
(act on other glands) - all peptides/proteins
thyrotropin (thyroid stim hormone) - thyroid
luteinizing hormone - testes, ovaries
follicel-stim hormone - ovaries
corticotropin - adrenal cortex in adrenal glands
corticosteroids: cortisol, aldosterone, sex steroids
main glucocorticoid is cortisol
Response to stress but slower and lasts longer than epinephrine and norepinephrine response
Some cells directed to decrease use of glucose and shift to fats and protein
Inhibits the immune system
Cortisol and similar drugs used to reduce inflammation and allergic reactions
also produces
prolactin
growth hormone
enkephalins
endorphins
lots of feedback controls
hypothalamus
releasing hormone (Corticotropin-releasing hormone
(hypothalamus))
anterior pituitary
tropic hormone (Corticotropin
(anterior pituitary))
endocrine gland
hormone (Cortisol (adrenal cortex) )
some redundnacy