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6-Responding to Change Flashcards

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1
Q

What are the 4 stages of coordianting response

A
  1. stimulus
  2. Receptors
  3. Coordinators
  4. Effectors
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2
Q

What is tropism

A

Directional Growth

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3
Q

Describe phototropism in the shoots and roots

A

Shoots are positively phototropic, grow towards light
Shoots are negatively phototropic, grow away from light

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4
Q

Describe Gravitropism in shoots and roots

A

Shoots are negatively gravitropic, grow up
Roots are positievly gravitropic, grow down

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5
Q

What is IAA

A

Indoleacetic acid, growth factor
synthesised at tips of roots and shoots

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6
Q

How is IAA distributed

A

Can be transported via diffusion or active transport over short distances, when plants detect stimuli
Uneven distribution, the concentration determines rate of cell elongation within region of elongation

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7
Q

What is the process of IAA

A

IAA binds to receptor proteins on CSM, stimukating ATPase proton pumps, pumping protons from cytoplasm to the cell wall
This acidifes the cell wall, activating the protein “expansins”, which losens bonds between cellulose microfibrils, so they can be more easily stretched when turgor increases.
K+ ion channels are stimulated to open, increasing K ion conc in cytoplasm, decreasing water potential, so cell absorbs water by osmosis, stored in vacuole, increasing internal pressure of cell, stretching cell wall, elongating the cell

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8
Q

In shoots, how does IAA act, with a light stimulus

A

Positevly phototropic
IAA transported to more shaded part, so cells elongate in shaded part, shoot bends towards light

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9
Q

In roots, how does IAA work, in response to light

A

IAA transported to more shaded part
Higher conc of IAA inhibits cell elongation

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10
Q

What impact does gravity have on IAA

A

IAA pulled closer to gravity

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11
Q

What is Taxis

A

Directional response to stimuli, move away or towards

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12
Q

What is Kineses

A

Non directional response to stimuli
Rate of movement affected by intesity of stimulus

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13
Q

What are the three neurons involved in the reflex arc

A

Sensory
Relay
Motor

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14
Q

Where are relay neurons found

A

Within central nervous system

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15
Q

What happens when receptors are stimulated

A

Create generator potential in sensory neuron

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16
Q

Describe the structure of the pacinian corpuscle

A

Mechanoreceptor found deep in skin
Found at ends of sensory neuron axons
Layers of membrane separated by gel containing excess Na+, and stretch mediated sodium ion channels

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17
Q

Describe the proccess of a pacinian corpuscle being stimulated

A

in resting state, inside neurone more negative than outside (-70mV)
When pressure applied to PC, rings of connective tissue apply pressure on sensory neuron, causing layers of the membranes to be distorted, causing stretch mediated Na+ channels to open
Na+ ions flood into axon, via facillitaed diffusion
charge inside neuron more positive than outside, leading to depolarisation, leading to an action potential in sensory neuron

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18
Q

How is a generator potential produced in the eye

A

Breakdown of optical pigments

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19
Q

What is the pathway from rod and cone cells to the brain

A

-> synapses -> Bipolar neurons -> synapses -> Ganglion cells -> axons -> optic nerve -> brain

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20
Q

What are rod cells sensitive to

A

Light intensity

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21
Q

Compare the visual acuity between rod cells and cone cells

A

Rod cells, lower, as multiple cells to single bipolar to multiple ganglion cell. The brain can’t interpret whihc impulse was sent by which specific rod
Cone cells, higher, single cell to single bipolar, to single ganglion (2 stimulated, brain interprets 2 dif spots of light)

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22
Q

What pigment to cone cells contain, and what are the conditions for it to break down

A

Iodopsin
Bright light only

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23
Q

What pigment to rod cells contain, and what are the conditions for it to break down

A

rhodopsin
breaks down in dim light

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24
Q

Name and describe how an additive effect in rod cells would help nocturnal animals

A

Summation
If group of rods stimulated at same time, co,bined generator potentials sufficient to reach threshold, to stimulate bipolar cell
Less sharp image, but enables organisms to see in dimmer light

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25
Q

What are cone cells sensitive to and how do they work

A

Different wavelengths of visible light (colour)
3 dif types with dif pigments sensitive to dif wavelengths of light:
red sensitive, blue sensitive, green sensitive
Combined effect allows us to see all colours on visible spectrum

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26
Q

What are the 6 features of the structure of the eye

A

Cornea - transparent lens refracts light as it enters
Iris - controls how much light enters
Lens - Transparent disc, can change shape to focus light on retina
Retina- contains light receptor cells (rods and cones)
Optic nerve - sensory neuron carries impuslses between eye and brain
Pupil - hole allowing light to enter eye

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27
Q

Whats the term for the control of basic heatbeat

A

Myogenic

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28
Q

What is the type of rhythm when the heart beats without external stimuli

A

intrinsic rhythm

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29
Q

What are the 5 stages of the heart beat

A

1- sinoatrial node (SAN) sends out wave of excitation
2- Atria Contract
3- Atrioventricular node sends out wave of excitement
4-Purkyne tissue conducts wave of excitement
5- Ventricles contract

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30
Q

What is the SAN

A

Sinoatrial node
group of cells in wall of right atrium
initiates wave of depolarisation causing atria to contract

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31
Q

what is the Annulus Fibrosis

A

region of non- conducting tissue
prevents depolarisation spreading straight to ventricles
carries depolarisation to AVN - atrioventricular node

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32
Q

What is the AVN

A

Antrioventricular node
region of conducting tissues between atria and ventricles

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33
Q

Where does the AVN pass stimulation to

A

Bundle of His

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34
Q

What is the bundle of His

A

collection of conducting tissue in septum of hear
Divides into 2 conducting fibres - purkyne tissue
Carries wave of excitation along them

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35
Q

What are purkyne fibres

A

spread around ventricles
initiate depolarization of ventricles from apex (bottom) of heart
Causes ventricles to contract

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36
Q

What is the name for the cardioregulatory centre

A

Medulla

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37
Q

Describe the Medulla

A

Cardioregulatory centre, found at base of brain, near top of spinal cord
Specific region of brain that controls the heart rate
2 parts: Accelertory and inhibitory centres
Both connected to SAN by nerves (dif to nerves that control concious activity) (automatic nervous system)

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38
Q

What happens when the acceleratory centre is activated

A

Impulses sent along sympathetic neurons to SAN
Noraderenaline secreted at synapse with SAN
Causes SAN to increase frequency of electrical waves
Increases heart rate

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39
Q

What happens when the inhibitory centre is activated

A

Impulses sent aling parasympathetic neurons to SAN
Acetylcholine (neurotransmitter) secreted at synapse with SAN
Causes SAN to reduce frequency of electrical waves
Reduces heart rate to resting rate

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40
Q

To increase the heart rate, what is secreted and where

A

Noradrenaline
Synapse with SAN

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41
Q

To decrease heart rate, what is secreted and where

A

Acetylcholine (neurotransmitter)
Synapse with SAN

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42
Q

What internal stimuli does exercise cause

A

CO2 conc in blood increases
Initial fall in blood pressure - caused by dilation of muscle arterioles

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43
Q

What are internal stimuli detected by, in releation to the heart, and where are they

A

Chemoreceptors
Pressure receptors

In aorta, close to heart and carotid arteries

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44
Q

what do carotid arteries do

A

supply heart with oxygenated blood

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45
Q

Describe Adrenaline

A

Hormone
Produced by adrenal glands
Chemically similar to noradrenaline
Released during fight or flight
Causes heart rate to increase

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46
Q

What is a nerve

A

Bundle of neurons

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47
Q

What is an axon

A

Long fibre
Some insulated by fatty sheath

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48
Q

What are the nodes of Ranvier

A

Small unisulated section along length of axon allowing electrical impulse to jump between- speeding up conduction of impulse

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49
Q

What is the axon sheath made of and how

A

Myelin
Substance made by Schwann cells

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50
Q

What is the purpose of Schwann cells

A

Make myelin
Wrap themselves around axon aling length

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51
Q

WHat is the term for the “jumping” of electrical impulse from node to node

A

saltatory conduction

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52
Q

What are the extensions of the neuron cell bodies called, and what is the purpose

A

Dendrites
Connect to many other neurons and recieve impulses from them

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53
Q

What are the features of the motor neuron

A

Large cell body at one end- lies within CNS
Nucleus in cell body
Many hughly branched dendrites- large SA for other neurons’ axon terminals

54
Q

In a resting axon

A

Inside axon has negative electrical potential compared to outsode
roughly -70mV compared to outside

55
Q

How is an electrochemical gradient estabilished in neurons

A

Sodium potassium pumps (carrier proteins) present in membranes of neurons
Use ATP to actively pump 3NA+ ions out for every 2K+ in
So larger conc of + ions outside than inside

CSM has selective protein channels, allow Na+ and K+ move across membrane by facillitated diffusion, down concentration gradient
More permable to K+ than Na+, so K+ diffuses out of axon at faster rate than Na+ back in

56
Q

What happens in a neuron when an action potential is stimulated

A

1-Na+ channels open
2-Na+ pass into axon down electrochemical gradient, decrease negative charge (inside axon becomes less negative) : depolarisation
3-Depolarisation triggers more channels to open, more Na+ enters, more depolarisation (positive feedback small-> big depolarisation)
4-PD reaches threshold (-50mV) more chanells open, more Na+ enters, inside reaches +30mV - action potential generated
5-Depolarisation of membrane at first AP site causes Na+ to diffuse along axon, depolarising next section, causes Na+ voltage-gated channel proteins to open there - conduction
6- triggers production of another AP in section, repeats

57
Q

How does repolarisation occur

A

1- 1ms after AP in section generated, all Na+ voltage-gated channel proteins in section close - stops Na+ diffusing into axon
2- K+ V-G channel proteins open, K+ diffuses out
3- PD returns to -70mV (normal) : repolarisation, short period of hyperpolarixation, PD across section becomes more negative than normal RP
4- K+ V-G close, Na+ CP become responsive, but until this happens, section in period of recovery, unresponsive- Refractory period

58
Q

Describe the refractory period, and it’s improtance

A

Period of recovery when neuron is unresponsive
Ensures “new” AP are generated further along axon, rather than behind- so discrete series of events- travel in one direction- successful and efficient transmission
Length key to determining mx frequency impulses can be transmitted - 500 -1000 per second

59
Q

What 3 factors affect speed of conduction

A

Myelination
Diameter
Temperature

60
Q

How does myelination affect the speed of conduction

A

Unmyelinated - very slow speed, depolarisation must occur along whole membrane of axon
Insulation, increases speed AP can travel, as depolarisation can only occur at nodes of ranvier,
local circuits that trigger depolarization in next section exist between nodes
saltatory conduction due to schwann cells

61
Q

How does Diameter affect the speed of conduction

A

Higher speed along neurons with thicker axons

Thicker= greate SA of membrane, which diffusion can occur, increase rate through protein channels->increase depolarisation and AP

greater diameter = greater volume of cytoplasm
Contains ions, reduces electrical resistance, AP pushes to next section faster

62
Q

How does temperature affect the speed of conduction

A

for cold blooded reptiles, other animals with variable body temps due to environments
Colder-> slower-> less kinetic energy for facilitated diffusion of ions

63
Q

What is the gap between two neurons called

A

Synaptic cleft

64
Q

How do electrical impulses travel across a synapse

A

1- Neurotransmitters released from vesicles in presynaptic neuron
2-NT diffuse across synaptic cleft
3- Temporarily bind with receptor molecules on postsynaptic membrane
4-Stimulates PostS N to generate elctrical impulse that travels down PostS N
5-NT destroyed/recycled, preventing contiuned stimulation of PostS N

65
Q

WHat type of synapse used acetylcholine (ACh) as an neurotransmitter

A

Cholinergic synapses

66
Q

How does Transmission across a cholinergic synapse occur

A

1- AP arrives at PreS M, causing depolarisation of the membrane, which stimulates V-G Ca+ ion protein channels to open
2-Ca+ diffuses down elctrochemical grad, from tissue fludi surrounding synapse, to cytoplasm of PreSN
3-Stimulates ACh-containing vesciles to fuse with PreS M, releasing ACh molecules to synaptic cleft
4-ACh molecules diffuse across synaptic cleft, temporarily bind with ligand-gated Na+ channels (receptor proteins) in PostS M
5-Causes conformation shape change in receptor proteins, open, allow Na+ to diffuse down electrochem grad into cytoplasm of PostSN
6-Na+ causes depolarisation of PostSM, restarts elec impulse, continues down axon
7-ACh broken down, recyled, prevent Na+ staying open permanently, permanent depolarisation (acetylcholinesterase ACh->acetate &choline)
8-Choline absorbed to PreSM, recates with acetyl conezyme a->ACh, packaged into vesicles
5-10 ms

67
Q

How do synapses ensure unidirectionality

A

NT released on one side, receptors on other
Prevents impusles travelling back to inititiation

68
Q

What is ther term for, and effect of, the combination of different stimuli

A

Summation
Allows for effect to be magnigied, to trigger response
Avoids nervous system being overwhelmed by impulses
Synapses act as barrier, slow down transmission rate

69
Q

Describe the two types of summation

A

Temporal summation - Multiple impulses within quick succession, added together to generate AP

Spatial Summation - multiple impulses arrive simultaneously at dif synaptic knobs stimulating same cell body

70
Q

How does neuron inhibition work

A

Some NT prevent generation of AP in PostSN, impulse stops at synapse
Open gated K+ channels in membrane, so K+ diffuses out
Cancels out effect if subject to excitarory , so threshold not reached
Prevent random impulses being sent round by body, allow specific pathways to be stimulated

71
Q

How can drugs affect synapses

A

Stimulate release of NT
Provide chems needed to synthesise NT
Act in same way as NT, bind to same receptor
Prevent reuptake of NT by PreSN

72
Q

Whats the name for the synpase like space between a neuron and muscle cell

A

Neuromuscular junction

73
Q

How does transmission across a neuromuscular junction work

A

ACh binds to receptor proteins on sarcolemma
Stimulates Na+ channels to open, diffuses in
Depolarises sarcolemma, generates AP
AP passes down T-tubules towards centre of muscle fibre
AP causes V-G Ca+ CP in sarcoplasmic reticulum to open
Ca+ diffuses out SR to sarcoplasm surrounding myofibrils
Ca+ binds to troponin molecules, causing conformational shape change
Causes troponin and tropomyosin to change position on actin filaments
Myosin-binding sites exposed on actin filaments
Sliding filament model begins

74
Q

What is a sarcolemma

A

Surface membrane of muscle fibre cell

75
Q

Where is the sarcoplasmic reticulum

A

Lie close to T-Tubules

76
Q

Whats the name for the thin muscle filaments

A

Actin

77
Q

Whats the name for the thick muscle filaments

A

Myosin

78
Q

What are tendons, and how do they function

A

Lengths of strong connective tissue
attach skeletal muscle to bones
Flexible, but don’t stretch when muscle contracts and pulls on bone

79
Q

Describe an antagonistic pair

A

Agonist- contracted
Antagonist- relaxed

80
Q

What is isometric contraction

A

muscle contraction without motion
to maintain posture, by contracting at joints to keep at certain angle

81
Q

What is striated muscle

A

makes up muscles in body attached to skeleton
made of muscle fibres

82
Q

Desribe a muscle fibre

A

Highly specialised cell-like unit
Contains organised arrangement of contractile proteins in sarcoplasm
surrounded by sarcolemma
contains many nuclei- why not referred to as cells

83
Q

Describe the sarcolemma

A

Cell surface membrane equivalent
FOlds inwards to sarcoplasm at certain points
Inwards fold: Transverse (T) tubules, run closer to sarcoplasmic reticulum, important to intitiating muscle contraction

84
Q

Describe the sarcoplasm

A

Cytoplasm equivalent

85
Q

Describe the sarcoplasmic reticulum (SR)

A

Endoplasmic reticulum equivalent
organelle in sarcoplasm
Store for Ca 2+ ions, important for muscle contraction
Membrane contain protein pumps, transport Ca 2+ into lumer of SR

86
Q

Describe Myofibrils

A

bundles of actin and myosin protein filaments
Located in sarcoplasm
Cylindrical organelles
Run along length of muscle fibres
Site of muscle contraction
Highly specialised
Made of multiple units (sarcomeres) run end to end along myofibril

87
Q

Describe actin

A

Make up thin filaments
globular protein molecules
Many link together to form chain, 2 chains twist together to form one filament
Tropomyosin (fibrous protein) twists around 2 chains
Troponin (protein) attached to actin chain at regular intervals

88
Q

Describe myosin

A

Makes up thick filaments
Fibrous protein molecules, anchors molecule into thick filament
Globular head points away from M-line

89
Q

How are actin and myosin protein filaments arranged

A

Alternating pattern in sarcomeres
Mysoin in middle, overlap with thin at each end

90
Q

Whats the A-Band

A

Overlap region
Contains overlap, and only myosin
Visually dark bands

91
Q

Whats the H zone

A

Only thick filament region

92
Q

Whats the middle of the sarcomere called, and its function

A

M-line
Attachment for myosin

93
Q

Whats the I-Band

A

Only thin region
Visually light bands

94
Q

WHats the end of a sarcomere called

A

Z-line

95
Q

Describe the sliding filament theory

A

Explains houw muscle contraction is coordianted
Sarcomeres within myofibrils shorten as z discs pulled closer together
1. sarcolemma depolarises
2.Sarcolemma contracts - depolarisation->myosin and actin filaments slide over each other, sliding -> contraction
3. Muscle contracts
4. Muscle relaxes, as sarcomeres relax, and filaments slide back over eachother

96
Q

How does a sarcolemma depolarise

A

AP arrives at NM junction
Ca 2+ released from SR
Binds to troponin molecules, stimulates shape change
Troponin and tropomyosin change position on actin filament
Myosin binding sites exposed on actin filaments
Globular heads of myosin molecules bind with sites, form cross bridge between 2 types of filament, myosin head spontaneously bend, release ADP and inorganic phosphate, pulls actin filaments towards centre of sarcomere, cuases muscle to contract v small distance
ATP binds to myosin heads, shape change, release actin
ATP hydrolase ATP->ADP+Pi, myosin heads move back to og position- Recovery stroke
Mysoin heads bind to new binding site, closer to z disc
Move again, sarcomere shortens again, repeats
Until troponin and tropomyosin are blocking binding sites

97
Q

what are the two types of binding sites on every myosin head

A

Actin
ATP

98
Q

How does aerobic respiration supply ATP for which kind of movement

A

Oxidative phosphorylation
Extended periods of low intensity muscle use

99
Q

How does anaerobic respiration supply ATP for which kind of movement

A

Glycolysis, lactate fermentation
SHort periods high intesity

100
Q

What is phosphocreatine

A

Molecule that can be used for rapid ATP production
During intense muscular effort, P donates phosphates to ADP->ATP + creatine
Low muscle activity, ATP phosphorylates-> phosphocreatine

101
Q

What do calcium ions also do (besides its interaction with troponin) to aid muscle contraction

A

Activates ATP hydrolase
Releasing energy that powers muscle contractions

102
Q

What processes does ATP drive in the sliding filament theory

A

From Ca 2+ induced hydrolysis: myosin head bends
Breaking myosin-actin cross-bridge

103
Q

How is muscle contraction halted

A

AP no longer stimulating muscles, so release of Ca 2+ from SR stops, transported back into SR by active transport
Removing Ca 2+ troponin moves back and blocks binding sites
Sarcomere lengthens, muscle not contracting

104
Q

Where are slow twitch fibres

A

back and neck, migrating birds

105
Q

Where are fast twitch fibres

A

Arms, legs, eyelids, birds that flee from predators

106
Q

What is the function of slow twitch fibres

A

Contract more slowly
sustained activity
for posture

107
Q

What is the function of fast twitch fibres

A

Contract rapidly (myosin heads bind and unbind 5x faster) (so large amounts Ca 2+ needed)
Rely on anaerobic respiration for ATP
Fatigue quickly, due to lactate

108
Q

How are slow twitch fibres adapted to their function

A

Long thin muscle fibres
Contract slowly
Denser network of capillaries - shorter diffusion distance- good supply O2
High amounts myoglobin, haemoglobin, mitochondria, increases rate O2 supply absorb, dark red

109
Q

How are fast twitch fibres adapted to their function

A

Short wide muscle fibres
Contract quickly
Fewer capillaries, slow oxygen & glucose supply
Low amounts myoglobin, O2 store increase
absorption from capillaries so paler

110
Q

What is the energy source for fast twitch and slow twitch fibres

A

Slow- Aerobic
Fast- anaerobic

111
Q

Compare the cell structure of Fast and slow twitch fibres

A

Slow: more mitochondria, cappilaries
Lower levels of glycogen, phosphocreatine
Larger stores of myglobin (pigment that stores O2)(appear red)
Less SR (contains calcium 2+ ions)

112
Q

What are the effects of fatigue

A

Lactate lowers pH of muscles, affecting contractions of fibres
Calcium ion levels may decrease after repated contractions

113
Q

What is homeostasis

A

Maintenance of optimal conditions for enzyme action and cell function

114
Q

What does the nervous system consist of

A

Central nervous system - brain & spinal cord
Peripheral nervous system -all nerves in body

115
Q

What system are hormone part of

A

endocrine system

116
Q

Desrcibe hormones

A

Chemical substances produced by an endocrine gland
Carried by blood
Transmit info from 1 part to another, bring about change
Alter activity of 1/more specific target organs, with receptors hormones can bind to
To control functions that don’t need an instant response

117
Q

What is, and describe the features of, a gland

A

Group of cells that produce and release 1 or more substances through secretion
Have good blood supply, so ASAP into blood plasma

118
Q

Describe primary messengers

A

Don’t enter cells
Exert action on cell membrane by binding to receptors and triggering change within cell
Change can be activation of another molecule or initiate a reaction
E.g. Hormones: adrenaline, glucagon

119
Q

Describe Secondary messengers

A

Initiate and coordinate responses within a cell
Usually activated by binding of primary messenger to cell surface receptor
E.g. Cyclic AMP (cAMP)

120
Q

What is positive feedback and give an example

A

Original stimulus produces response that causes factor to deviate even more from normal range, enhancing the effect of the original stimulus
e.g. Bone repair

121
Q

How does bone repair work

A

Osteoblasts secrete hormone “osteocalcin” in inactive form
Osteoclasts secrete acid, lowering the pH, actvate osteocalcin
Active osteocalcin binds to receptor on beta cells in pancreas, stimulates to release insulin
Osteoblast cells have insulin receptors, become stimulated, so release more inactive osterocalcin
Osteoblast enhances effect of O.g. stimulus- positive feedback

122
Q

What is the importance of maintaining blood glucose levels

A

Meet demand of respiring cells- too low, insufficient
Maintain Water potential- too high, water leaves cells, die, and increased blood pressure

123
Q

What are blood glucose levels monitored by

A

Pancreas

124
Q

What happens if blood glucose level too high

A

“Glycogenesis”
Liver cells produce enzymes to convert glucose -> glycogen
Glycogen stored in liver cell’s cytoplasm

125
Q

What 2 things happen if blood glucose level is too low

A

Glycogenolysis
Liver cells produce enzymes break down glycogen-> glucose

Gluconeogenesis
Liver cells form glucose from glycerol and amino acids

126
Q

When blood glucose is above optimum concentration, what happens with insulin

A

1-Detection by beta cells in islets of Langerhans, pancreas. Glucose absorbed in beta cells, via carrier proteins (facilitated diffusion), causing insulin containing vesicles to move towards CSM, where released in capillaries
2- Insulin hormone secreted into blood, travels to liver and muscle cells, insulin binds to receptors on membranes

127
Q

What affect does insulin have on muscle cells

A

Insert more glucose channel proteins in cell membrane
Increase permeability of cells to glucose,
Rate of uptake (faciliated diffusion) of glucose by muscle increases
Rate of respiration in muscle increases

128
Q

What affect does insulin have on the liver

A

Stimulates glycogenesis (glucose to glycogen)
Glycogen is compact and efficient carbohydrate storage molecule
Glucose enters liver cell, enzyme rapidly converts glucose-> glucose phosphate
Dif enzyme glucose phosphate -> glycogen
lowers conc within liver cell, steep diffusion gradient between capillary blood and liver cells maintained, so lowers BGC

129
Q

What is the function of glucagon

A

When BGC below optimum temp:
1- Glucagon hormone (first messenger) secreted into blood, travels to liver
2 - Glycogeneolysis
3- Gluconeogenesis
4-glucagon slows rate of respiration in cells, hence slowing rate at which glucose is used up

130
Q

What happens in glycogenolysis

A

glucagon binds to receptros on liver cell membranes,
causing conformational shape change in receptor protein,
enzyme cascade,
to glycogen phosphoyralse enzymes that catalyse the breakdown of glycogen -> glucose

131
Q

What happens in gluconeogenesis

A

Synthesis of glucose from noncarbohydrate moleules
Glucagon activates enzymes in liver
convert other molecules (e.g. fatty acids, amino acids) to glucose

132
Q

WHat is the function of adrenaline

A

Response to low BGC or exercise or stress
1- secreted from adrenal gland
2- Binds to receptors in liver cell membrane, causing enzyme cascade
3- activates glycogenolysis, inhibits glycogenesis, prmotes secretion of glucagon from pancreas, inhibits insulin secretion

Biology (5 decks)

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