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animal and plant responses Flashcards

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1
Q

what does Mimosa pudica do?

A

carries out a thignomastic response (non-directional touch response)
due to threat of herbivores

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2
Q

how does Mimosa pudica respond to herbivores?

A

leaves curl up because cells in leaf becomes flaccid
mechanoreceptors are stimulated by change in pressure so ions are pumped out (active) of leaf cells and H2O follows down water potential gradient into stem

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3
Q

explain 2 structural defences (anatomical adaptations) a plant may have to discourage consumption by herbivores

A

spikes, thorns and barbs may cause pain or may introduce a poison/allergen into the herbivore
lignin=woody impermeable molecule so very difficult to eat and digest

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4
Q

examples of chemical defences

A

phenols
flavonoids
tannins

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5
Q

why do plants use chemical defences against herbivores

A

provide a bitter taste to the herbivore to deter it
poisonous so act as non-competitive enzyme inhibitors to disrupt enzymes

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6
Q

example of pheromone

A

ethene

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7
Q

what are pheromones w/ example

A

gases that influence the behaviour of members of same species or herbivore
e.g. tomato plants can ‘alert’ other plants of impending threat by herbivores so become bitter

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8
Q

tropism definition

A

a directional growth response towards a stimulus

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9
Q

4 types of tropism

A

thigmotropism
phototropism
hydrotropism
geotropism

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10
Q

what is a thigmotropism
example
function

A

response to touch
e.g. vine growing around a wooden pole
supportive for plant

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11
Q

what is a phototropism (both kinds)

A

positive: shoots grow towards light ti obtain light energy for p/s
negative: roots grow away from light to access water and minerals in soil and provide stability

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12
Q

what is hydrotropism
function

A

growth towards water
obtain H2O which is a reactant for p/s

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13
Q

what are both kinds of geotropism w/functions

A

positive: roots grow towards gravity so plant can gain water and mineral ions from soil and the plant has better anchorage and support
negative: shoots grow away from gravity to obtain light energy for p/s

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14
Q

nastic response definition

A

non-directional response to a stimulus which may or may not include growth

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15
Q

explain how M.pudica closes up its leaves in response to touch

A

mechanoreceptors stimulated by change in pressure
ions pumped out of leaf cells’ vacuoles (Cl- and K+) (active)
H2O follows out down water potential gradient (bc water potential outside cell is more negative)
the flexor cells stretch, extensor cells become flaccid
leaf curls and cells become flaccid so stomata close

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16
Q

how might thigmonastic response in plants help them to survive?

A

e.g. M.pudica
appear smaller to herbivores so less likely to be eaten
discourages predation by insects
protection against fire bc less SA exposed

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17
Q

suggest why plant growth regulators are called hormones although they are not produced in endocrine glands

A

plant hormones must still bind to specific receptors
they are transported from their site of synthesis to their target

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18
Q

explain why only certain tissues in a plant respond to a particular plant hormone

A

hormones bind to specific complementary receptors on plasma membrane of specific cells to trigger a response (series of reactions)
these receptors are only present in certain tissues

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19
Q

3 ways that plant hormones can move around the plant

A

diffusion
active transport
xylem (dissolved in water as transpiration stream) (facilitated)

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20
Q

what are IAAs

A

auxins

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21
Q

what is the role of auxin

A

cell elongation

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22
Q

mechanism of auxin step by step

A

auxin released from meristematic cells at shoot tip and diffuses down shoot tip from high to low concentration
auxin binds to specific receptors on plasma membranes of cells in the shoot
activates proton pumps to actively transport H+ into cellulose cell wall
presence of H+ ions in the cell wall reduces pH and activates expansions, which catalyse breaking of H bonds between cellulose macrofibrils and microfibrils
cellulose cell wall is now flexible and elastic
water enters the cells and elongates the cells as it enters the vacuole

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23
Q

characteristics of the zone of cell differentiation

A

higher pH as les IAA present
expansins denature and H bonds reform in cellulose (no longer flexible)

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24
Q

what does apical dominance ensure

A

that trees/plants grow tall and obtain as much light energy as possible

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25
Q

what is apical dominance

A

auxin released from the apical shoot tip/bud inhibits growth of lateral branches/shoots

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26
Q

how do some hormones overcome apical dominance

A

apply cytokinins to overcome apical dominance and promote cell division and growth of lateral shoots

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27
Q

experimental example of apical dominance

A

one intact shoot and one decapitated
intact shoot: IAA produced from shoot tip promotes apical dominance so sugars produced in p/s are not used to promote lateral growth
decapitated shoot: source of IAA removed so lateral shoots can grow and sugars like sucrose can be repaired to produce ATP for growht

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28
Q

what does germination require

A

O2 (aerobic respiration)
warm temperature (KE for enzymes)
water (activates gibberellins)

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29
Q

mechanism of gibberellins in germination step by step

A

water is absorbed by seed to soften seed coat to allow young root (radicle) and young shoot (plumule) to break out of seed
gibberellins (gibberellin acid) are activated in the embryo. they diffuse from embryo to the aleurone layer, bind to specific receptors on the plasma membranes of cells. they initiate transcription/translation of genes encoding digestive enzymes e.g. amylase, protease, maltase
starch in seed digested by amylase into maltose which is digested by maltase into alpha glucose. proteins are digested by proteases to produce amino acids

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30
Q

examples of plant responses to abiotic changes/stresses

A

stomatal closure
leaf loss/abscission in deciduous trees
photoperiodism
freezing conditions

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31
Q

examples of plant responses to abiotic changes/stresses: STOMATAL CLOSURE

A

prevents wilting
1. low soil water potential is detected by the roots
2. ABA synthesised and travels up the xylem via the transpiration stream to the leaves
3. ABA binds to a specific receptor on the plasma membrane of guard cell and stimulus stomatal closure. ATP is used to pump ions out of guard cells, reducing the water potential outside of the cell so water moves out by osmosis down the WP gradient

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32
Q

examples of plant responses to abiotic changes/stresses: LEAF LOSS/ABSCISSION IN DECIDUOUS TREES and fruit drop

A

when auxin levels are high, leaves do not drop
when auxin levels drop, ethene levels increase, which triggers the transcription and translation of cellulase genes
cellulase digests cellulose cell walls and leaves/fruits drop/ are abscised

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33
Q

examples of plant responses to abiotic changes/stresses: PHOTOPERIODISM

A

a plant’s photoperiod related to the number of daylight hours required for flowering
controlled by a set of proteins called PHYTOCHROMES

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34
Q

examples of plant responses to abiotic changes/stresses: FREEZING CONDITIONS

A

some plants can synthesise antifreeze proteins in low temps, lowering the freezing point of the vacuole cell sap, enabling survival in cold winter months
ALSO in cold temps, SER synthesises cholesterol which intersperses itself between phospholipids, increasing the fluidity of the phospholipid bilayer

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35
Q

commercial uses of plant hormones

A

auxin to produce flowers, grow cuttings, produce seedless fruit and kill weeds
gibberellins to produce fruit, brew beer, produce cane sugar and breed plants
cytokinins to reduce lettuce wastage and clone plants
ethene

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36
Q

how are auxins used to produce flowers

A

prevents leaf and fruit drop so flowers can remain on shelves for longer

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37
Q

how are auxins used to grow cuttings

A

cutting taken between 2 nodes at an angle
lower leaves
cut stem dipped in rooting powder containing auxin
cut stem replanted in moist soil and covered with a transparent polythene bag

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38
Q

how are auxins used to produce seedless fruit

A

known as parthenocarpy
treat unpollinated flowers w/ auxin
promotes ovule growth and auxin release in the developing fruit
no seeds remain in the fruit

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39
Q

how are auxins used to kill weeds

A

promote excessive shoot growth (cell elongation) so stem cannot support itself, buckles and dies

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40
Q

how are gibberellins used to produce fruit

A

applied to grapes to elongate stalks, allowing grapes more space to grow. larger and less compact bunches w/ larger grapes produced
applying gibberellins can delay senescence (ageing) in citrus fruits to improve shelf life
working synergistically w/ cytokinins to elongate and improve shape of apples

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41
Q

how are gibberellins used to brew beer?

A

speeds up germination of barley seeds (amylases and maltase are produced quicker)
barley then turns into malt

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42
Q

how are gibberellins used to produce cane sugar?

A

gibberellins cause stem elongation between the nodes
sugar cane stores sugar in cells in the internodes so elongation makes more available from each plant

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43
Q

how are gibberellins used to breed plants?

A

gibberellins can speed up seed production and germination in young conifer plants
seed companies can induce early seed formation in biennial plants (produce seeds after 1 year)
spraying gibberellins biosynthesis inhibitors can keep plants short and stocky to prevent lodging

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44
Q

how are cytokinins used to reduce lettuce wastage

A

applying cytokinins prevents yellowing of lettuce leaves after they have been picked

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45
Q

how are cytokinins used to clone plants

A

used as a growth hormone in micropropagation
promote bud & shoot growth by stimulating cell division in explants

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46
Q

describe the commercial uses of ethene

A

speeding up of fruit ripening in tomatoes, citrus fruits and apples
promoting fruit drop in cherry, cotton and walnut
promotes lateral growth in some plants
restricting ethene can prevent fruit ripening which is useful for storage and transport of bananas

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47
Q

effect of gibberellins on amylase produced in isolated tissues from barley seeds

A

exposure increases rate of amylase synthesis
gibberellins are activated in barley seeds’ embryo and diffuse to aleurone layer, and bind to specific receptors on PMs of cells
initiate transcription/translation of genes encoding amylase (enables starch to be digested into maltose)
w/ no treatment, amylase production is much slower and therefore plants need gibberellin for germination to occur

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48
Q

why would temperature be controlled in an experiment investigating auxin

A

higher temperature means higher KE of molecules so faster rate of diffusion

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49
Q

auxins site of production

A

shoot tips
root
shoot
apical bud

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50
Q

auxins effects

A

promotes cell elongation in shoot tips
inhibits cell elongation in root
inhibits leaf abscission (ethene production) in shoot
promotes apical dominance in apical bud

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51
Q

gibberellins site of production

A

seeds
stem

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52
Q

gibberellin effects

A

stimulates germination of seeds by causing digestive enzymes to be synthesised
work synergistically w/ auxins to promote stem elongation (internal growth) and promote lateral shoot growth
(effects of gibberellin are greater than effects of auxin on stem elongation)

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53
Q

ethene site of production

A

leaves

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54
Q

ethene effects

A

stimulates abscission/ fruit drop

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55
Q

abscisic acids site of production

A

roots
leaves
seeds

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56
Q

abscisic acids effects

A

inhibits cell division and therefore growth of roots
promotes stomatal closure in leaves
inhibits germination of seeds

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57
Q

cytokinins site of production

A

applied artificially to apical bud

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58
Q

cytokinins effects

A

overcomes apical dominance
used as growth hormone in micropropagation (promote bud and shoot growth by stimulating cell division in explants)

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59
Q

what does myogenic mean

A

initiates its own beats at regular intervals (doesn’t need to receive elec impulses from a neurone to make it contract)

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60
Q

how does SAN act as a pacemaker

A

initiates wave of excitation that sets the pace and rhythm for cardiac muscle cells to contract

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61
Q

typical resting heart rate

A

75bpm

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62
Q

path of wave of excitation in heart

A

SAN
AVN
bundle of his
purkyne fibres

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63
Q

step by step heart contraction

A

SAN initiates wave of excitation which spread over both atria simultaneously
short delay before AVN transmits WoE so atria can finish contracting
AVN transmits WoE to the ventricles
Bundle of His carries wave of excitation down the septum to the apex
purkyne fibres carry WoE over the surface of the ventricles and allow the ventricle walls to contract from apex upwards

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64
Q

where is the cardiovascular centre found

A

medulla oblongata

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65
Q

what is the heart rate controlled by

A

autonomic nervous system (involuntary) reflex action
nerves (motor neurones) run from cardiovascular centre to SAN

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66
Q

what is HR increased by

A

the accelerans nerve (sympathetic NS)

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67
Q

what is HR reduced by

A

vagus nerve (parasympathetic NS)

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68
Q

does parasympathetic or sympathetic NS dominate at rest?

A

VAGUS NERVE
although both provide slight stimulation

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69
Q

medulla oblongata nerve types

A

has excitatory and inhibitory nerves

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70
Q

how does vagus nerve act

A

releases acetylcholine (ACh) at synapses between neurones
causes hyperpolarisation of cardiac muscle

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71
Q

how does accelerans nerve act

A

releases noradrenaline at synapses between neurones
causes depolarisation of cardiac muscle

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72
Q

baroreceptors role

A

detect changes in blood pressure

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73
Q

chemoreceptors role

A

detect change in blood pH (CO2 content)

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74
Q

what do stretch receptors in skeletal muscles and joint capsules detect?
what does this trigger?

A

movement of limbs
sends elec impulses to medulla oblongata via sensory neurone
increase sympathetic nerve activity and decreases parasympathetic activity
HR increases so more oxy blood supply to muscles

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75
Q

where are chemoreceptors

A

carotid arteries
aorta
brain

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76
Q

chemoreceptors mechanism during exercise

A

CO2 conc in blood increases
chemoreceptors send impulses to medulla oblongata via sensory neurone
increase sympathetic and decrease parasympathetic nerve activity
increase HR and remove more CO2 from blood
after exercise, less CO2, blood pH increases so sympathetic nerve activity decreases

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77
Q

where are baroreceptors found

A

aortic arch
carotid artery
vena cava

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78
Q

baroreceptors role when BP increases

A

BR stimulated
more impulses to medulla oblongata
more stimulation of SAN
increased HR and SV

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79
Q

vena cava baroreceptors:
source of stimulation
nerve involved
outcome on heart

A

increased blood volume returning to the heart due to strenuous activity
more accelerans nerve stimulation
increased HR

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80
Q

aortic arch and carotid artery baroreceptors:
source of stimulation
nerve involved
outcome on heart

A

increased cardiac output
decreased accelerans and increased vagus nerve stimulation
decreased HR

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81
Q

2 branches of nervous system

A

central NS
peripheral NS

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82
Q

what is CNS made up of

A

unmyelinated grey matter (mostly)
white matter= axons of unmyelinated neurones

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83
Q

what is PNS made up of

A

somatic (voluntary)
autonomic (involuntary)

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84
Q

describe somatic NS

A

output to skeletal muscles via motor neurones
acetylcholine
includes somatic reflexes

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85
Q

autonomic NS output

A

glands, smooth muscle, cardiac muscle

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86
Q

branches of autonomic NS

A

parasympathetic
sympathetic

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87
Q

describe parasympathetic NS

A

rest and digest
conservaiton of energy
NT= acetylcholine
vagus nerve

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88
Q

descrie sympathetic NS

A

fight/flight response
internal alarm
NT= noradrenaline
accelerant nerve

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89
Q

somatic vs autonomic NS: control

A

S= volunatry
A= involuntary

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90
Q

somatic vs autonomic NS: neurones

A

S- sensory neurons form sense organs and motor neurones to skeletal muscles
A- input form internal receptors via sensory neurones to motor neurones that supply internal organs

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91
Q

somatic vs autonomic NS: target

A

S- skeletal muscles
A-cardiac muscle, smooth muscle, glands

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92
Q

somatic vs autonomic NS: ganglia

A

S-only 1 motor neurone, cell body in CNS
A- cell bodies of 2nd motor neurones are in ganglia outside the spinal cord: preganglionic neurone carries AP from CNS to ganglia, postganglionic neurone carries AP to target effector

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93
Q

somatic vs autonomic NS: myelination

A

S- most neurones are myelinated, allowing for fast responses. somatic reflexes r faster
A- most neurones unmyelinated. rapid response not as important for autonomic reflexes

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94
Q

parasympathetic vs sympathetic NS: origin of neurones

A

P: emerge from cranial and sacral regions of CNS
S: emerge from thoracic and lumbar regions of CNS

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95
Q

parasympathetic vs sympathetic NS: position of ganglion

A

p; close to effector
S; close to spinal cord

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96
Q

parasympathetic vs sympathetic NS: length of neurones

A

P; preganglionic is long, postganglionic is short
S; preganglionic short, postganglionic long

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97
Q

parasympathetic vs sympathetic NS: transmitter substance released at effector

A

P: acetylcholine
S: noradrenaline

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98
Q

parasympathetic vs sympathetic NS: time of greatest activity

A

P: rest/digest
S: fight/flight

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99
Q

parasympathetic vs sympathetic NS: effects on heart via SAN

A

P; lower HR and force of contraction
S; higher HR and force of contraction

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100
Q

parasympathetic vs sympathetic NS: effects on blood vessels

A

P; maintains steady muscle tone in arterioles to gut, smooth muscle, brain and skeletal muscle
S; dilates arterioles to brain and skeletal muscle, constricts arterioles to gut

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101
Q

parasympathetic vs sympathetic NS: effect on lungs

A

P: lower BR and depth
S: increased ventilation rate and depth

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102
Q

parasympathetic vs sympathetic NS: effect on eyes

A

P: pupils narrow
S: pupils dilate

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103
Q

parasympathetic vs sympathetic NS: effects on digestive system

A

P: stimulates peristalsis, stimulates secretion of juices from glands, inhibits contraction of sphincter muscles (faeces are passed), glycogenesis in liver
S: inhibits peristalsis, little effect on glands, contraction of sphincter muscles, gluconeogenesis and glycogenolysis in liver

104
Q

parasympathetic vs sympathetic NS: effects on skin

A

P: no effect on sweat glands, erector muscles or arterioles
S: increased sweat production, hair erector muscles contract so hairs raise, constriction of arterioles to skin

105
Q

describe reflex actions:
(determined by what?)
(is Brain involved?)

A

rapid automatic response
involuntary (no conscious thought)
follows a specific pattern in response to a given stimulus
it is determined by the presence of an inherited pattern of neurones forming spinal and cranial reflex arcs
brain may be informed that reflex has happened, but is not involved in co-ordinating response
usually have some sort of survival value

106
Q

examples of neurone pathways of reflex actions

A

SN-MN
SN-RN-MN
SN-RN-RN-MN
SN-RN-MN-MN

107
Q

what is a stimulus

A

detectable change in the environment

108
Q

what does a receptor do

A

(transducer) detects and coverts stimulus energy to an electrical input

109
Q

survival importance of reflexes?

A

prevent body being harmed of reduce severity of damage

110
Q

how do reflexes increase chances of survival

A

bc they are involuntary so decision-making regions of the brain are not involved so response is quicker
being present form birth means they dont have to be learnt and therefore provide immediate protection (innate behaviours)
they are extremely fast (reflex arc is as short as possible and normally only involves 2 synapses. some reflexes are monosynaptic)

111
Q

examples of reflexes (stimuli)

A

smell of food
hot plate
food in throat
bright light
tap on patella tendon

112
Q

reflex: smell of food:
receptor
effector
response
cranial/spinal?

A

olfactory cells in nose
salivary glands
secrete salia
cranial

113
Q

reflex: hot plate:
receptor
effector
response
cranial/spinal?

A

thermoreceptors in skin
bicep muscle
move hand away
spinal

114
Q

reflex: food in throat:
receptor
effector
response
cranial/spinal?

A

touch receptors in pharynx
smooth muscle of pharynx
swallow food
cranial

115
Q

reflex: bright light:
receptor
effector
response
cranial/spinal?

A

photoreceptors in retina
circular iris muscles contract
pupils narrow
cranial

116
Q

reflex:tap on patella tendon:
receptor
effector
response
cranial/spinal?

A

stretch receptors in quadreceps
quad muscle contracts
lower leg lifts
spinal

117
Q

blinking may be stimulated by sudden changes in the environment e.g.:

A

foreign object touching cornea
drying out of cornea
sudden bright light
loud sounds
sudden movement

118
Q

stages in blinking reflex

A

foreign body stimulates mechanoreceptors in cornea
AP transmitted along SN
AP passes along RN in lower brain stem (pons)
AP sent along branches of MNs
Obicularis Oculi (facial) muscle around eye pulls eyelid inward helping to close the eyelid

119
Q

how can blinking reflex be overriden/inhibited

A

involves 2 synapses so can be overridden by inhibitory signals from the cerebral cortex
higher centre can send inhibitory impulses much more rapidly than non-myelinated relay neurones in the pons
the inhibitory action can prevent AP forming in the MN
(essential for people who wear contact lenses)

120
Q

describe knee jerk reflex

A

stretch receptors in quadriceps muscles detect that muscle is being stretched
AP transmitted along SN
SN synapses directly w MN
MN transmits impulse to effector (quadriceps) causing it to contract and lower leg moves forward quickly
an inhibitory relay neurone inhibits MN to the antagonistic hamstring muscle causing it to relax (would interfere w reflex response otherwise)

121
Q

what type of reflex have monosynaptic reflex arcs

A

only stretch reflexes

122
Q

can the knee jerk reflex be inhibited

A

no because there are no relay neurones involved
polysynaptic arcs are required for a reflex to be inhibited as inhibition relies on the rapid myelinated neurones carrying APs to synapse before the MN is stimulated
therefore absence of this reflex may indicate NS problems

123
Q

what part of the brain is responsible for conscious thought and memory
(largest part)

A

cerebrum

124
Q

what is cerebrum divided into (and what are these connected by)

A

2 hemispheres: connected via the corpus callosum

125
Q

corpus callosum contains what and allows for what?

A

contains over 250 million nerve fibres
allows the 2 hemispheres of the cerebrum to communiacte

126
Q

cerebrum outer layer makeup

A

outermost layer (surface area 2.5m^2), is folded and consists of a layer of nerve cell bodies known as the cerebral cortex

127
Q

where is cerebral cortex more highly developed
what does it control

A

in humans
higher brain functions

128
Q

what higher brain functions does the cerebral cortex control

A

conscious thought and voluntary actions and emotional responses
ability to override some reflexes
features associated w intelligence e.g. reasoning, judgement, interpreting and learning
control of speech and visual processing

129
Q

hypothalamus function

A

regulates the autonomic nervous system
controls most of the body’s homeostatic mechanisms

130
Q

in-depth hypothalamus functions w parts responsible

A

osmoreceptors: responses mediated by pituitary gland
thermoregulatory centre: monitors blood temperature: responds via NS or hormonal via pituitary
regulates digestive activity: gut secretions/peristalsis controlled
regulates endocrine glands via the pituitary gland (thyroid and adrenal cortex)
involved in melatonin release to induce sleep

131
Q

what is medulla oblongata responsible for controlling (brief) so thus what is consequence

A

vital functions
damage here is fatal

132
Q

what does medulla oblongata form a link between

A

brain and spinal cord

133
Q

what does medulla oblongata control action of

A

non skeletal muscles (therefore used in autonomic control)

134
Q

examples of how medulla oblongata is used in autonomic control

A

contains respiratory centre- controls breathing and regulates rate and depth of breathing
contains cardiac centre- regulates heart rate
contains vasomotor centre- controls blood pressure and regulates circulation

135
Q

what does cerebellum co-ordinate

A

balance and learned sequences of movement (unconscious functions)

136
Q
A
137
Q

what is cerebral cortex divided into

A

sensory areas
association areas
motor areas

138
Q

what do sensory areas of cerebral cortex do

A

receive impulses indirectly from receptors via sensory neurones

139
Q

what do association areas of cerebral cortex do

A

compare sensory inputs with previous experience

140
Q

what do motor areas of the cerebral cortex do

A

send AP to various effectors

141
Q

what does frontal lobe of cerebrum contain and do

A

contains somatic motor associated area so co-ordinates movement

142
Q

what is occipital lobe of cerebrum responsible for

A

visual association

143
Q

what is parietal lobe of cerebrum repsonsible for

A

somatic sensory (touch) association

144
Q

what is temporal lobe of cerebrum responsible for

A

auditory association

145
Q

functions of the hypothalamus

A

regulation of thirst (osmoregulation), temperature (thermoregulation)
monitors chemical and hormone levels in the blood
controls the release of hormones eg ACTH from the anterior pituitary gland
produces hormones like ADH and oxytocin and causes their release from the posterior pituitary

146
Q

pathways of hormones from anterior pituitary gland

A

TRH stimulates TSH release, travels to thyroid which secretes thyroxine
CRH stimulates ACTH release, travels to adrenal cortex which secretes cortisol

147
Q

compare anterior and posterior lobe of pituitary gland

A

A: no direct nerve connection w the hypothalamus, P: direct nerve connection w hypothalamus
A: connected via portal blood system, P: no portal blood system
A: release TSH and ACTH into blood when a releasing factor from portal system binds, P: no releasing factors, AP from hypothalamus triggers release of ADH

148
Q

describe pathway of release of cortisol (negative feedback)

A

hypothalamus releases CRH
CRH travels in portal blood system to anterior pituitary
ACTH released and travels in blood to adrenal cortex
cortisol released from zona fasciculata
cortisol inhibits the release of CRH and ACTH (negative feedback), so switches off its own production

149
Q

parts of fight or flight response stimulated by hypothalamus

A

SYMPATHETIC NS:
impulses sent via motor neurones activate glands, smooth muscles, cardiac muscles
adrenal medulla activated to secrete adrenaline and noradrenaline
HORMONE RELEASE VIA ANTERIOR PITUATARY GLAND
TRH, pituitary secretes TSH, thyroid gland secretes thyroxine
CRH, pituitary secretes ACTH, cortisol released by adrenal cortex

150
Q

elements of fight/flight response (caused by sympathetic NS and hormone release)

A

more blood flow (vasodilation) to brain so more mental activity
dilated pupils (radial muscles contract)
higher HR, SV, BP so higher CO and more O2 to tissues
hairs stand up, more sweat production
vasodilation to muscles heart brain, vasoconsitrciton to gut and skin
increased BGL
increased BR so more O2 in

151
Q

how does activation of the fight/flight response affect voluntary muscle

A

breathing/intercostals contracting/diaphragm contracting faster
more blood flow to skeletal muscles
leg muscles primed for action
glycogenolysis in muscles

152
Q

how does activation of the fight/flight response affect involuntary muscle

A

arteriole smooth muscle relaxes to increase blood flow to the brain= vasodilation (caused by adrenaline)
radial smooth muscle in pupils contracts, pupils dilate (caused by adrenaline)
thyroxine increases metabolic rate and sweat production
arterioles contract/dilate to alter blood flow/pressure (less blood to gut/skin, less gut secretions and pale skin)
smooth muscle in airways relaxes so airways widen

153
Q

how does a stroke cause problems with coordination of movement, loss of memory/speech, paralysis of body below the neck

A

disruption of O2/glucose supply to brain cells for aerobic respiration
lack of O2/glucose/blood supply/damage to:
cerebrum/cerebral cortex so loss of speech/memory
cerebellum so problems w co-ordination/ movement
medulla oblongata so paralysis of body below neck

154
Q

explain why the cerebral cortex is a tissue whereas the brain is an organ

A

cerebral cortex is made up of a group of similar types of cell, working together to perform a similar function
the brain consists of several tissues carrying out more than one function

155
Q

state the region of the brain where the hypothalamus is found

A

forebrain

156
Q

list brief functions of hypothalamus

A

homeostasis
autonomic NS control
thermoregulation
hormone release
sleep control
pituitary gland control
osmoregulation
melatonin release

157
Q

region ion brain responsible for learning and memory

A

cerebrum

158
Q

region of brain responsible for control of balance and fine movement

A

cerebellum

159
Q

what part of the brain is involved with the ability to see

A

cerebral hemisphere

160
Q

hormone that stimulates glycolysis

A

adrenaline

161
Q

part of the brain that has nervous control of the heartbeat

A

medulla oblongata

162
Q

what are the 3 types of muscle

A

voluntary (skeletal)
cardiac
involuntary (smooth)

163
Q

description of voluntary/skeletal muscle

A

cell membrane=sarcolemma
cytoplasm=sarcoplasm
many mitochondria
multinucleate
extensive SER
number of myofibrils (organelles) make up contractile units called sarcomeres arranged end to end

164
Q

description of cardiac muscle

A

cells form branched fibres with cross bridges
cells separated by intercalated discs (specialised gap junctions that allow co-ordinated contraction) joining cells at ends
good supply of capillaries
abundant mitochondria (more reliant on aerobic respiration)

165
Q

description of involuntary/smooth muscle

A

spindle shaped
tapered at both ends
contains bundle of actin and myosin
single nucleus
forms sheets
numerous mitochondriav

166
Q

voluntary/skeletal muscle appearance under microscope

A

striated or striped or banded

167
Q

cardiac muscle appearance under microscope

A

striated or striped or banded due to myofibrils

168
Q

involuntary/smooth muscle appearance under microscope

A

unstriated bc no myofibrils (actin and myosin arranged differently)

169
Q

voluntary/skeletal muscle innervation

A

somatic nervous system (somatic reflexes)

170
Q

cardiac muscle innervation

A

myogenic but autonomic NS and hormones control rate

171
Q

involuntary/smooth muscle innervation

A

autonomic NS (sympathetic and parasympathetic)

172
Q

voluntary/skeletal muscle contraction

A

quick and powerful

173
Q

cardiac muscle contraction

A

quick
w/o NS (myogenic)

174
Q

involuntary/smooth muscle contraction

A

slow and sustained

175
Q

voluntary/skeletal muscle fatigues…

A

quickly

176
Q

cardiac muscle fatigue

A

does not fatigue due to lots of mitochondria

177
Q

involuntary/smooth muscle fatigues ….

A

slowly (doesn’t tie easily)

178
Q

where is voluntary/skeletal muscle found and what is its function

A

voluntary movements
attached to skeleton via tendons
contraction shortens the muscle and force is transmitted to bona via tendon and bone pulled
also somatic reflexes (involuntary)

179
Q
A
180
Q

where is cardiac muscle found and what is its function

A

in heart
contract to decrease volume in heart chambers to pump blood into ventricles or out of heart via arteries

181
Q
A
182
Q

where is involuntary/smooth muscle found and what is its function

A

intestine walls for peristalsis
uterus walls
arterioles to regulate BP and distribution of blood e.g. during exercise and temp regulation
reflexes e.g. in iris of eye

183
Q

describe structure of a skeletal muscle cell

A

each fibre/cell contains many nuclei and many organelles called myofibrils, which are embedded in the muscle fibre sarcoplasm and are surrounded by sarcoplasmic reticulum
T-tubules (infoldings of the sarcolemma)

184
Q

what are myofibrils composed of

A

protein filaments called myofilaments

185
Q

what does sarcoplasmic reticulum do

A

stores and secretes Ca2+
released to cause muscle contraction

186
Q

what do T-tubules allow to happen

A

allow APs propagating along the surface membrane to also travel throughout the interior of the muscle

187
Q

why does a muscle/fibre contain many nuclei

A

embryonic cells fused together to form individual muscle fibres

188
Q

what are myofibrils

A

long cylindrical organelles made of proteins called actin and myosin which are lined up in parallel
the myofibrils are the contractile elements of the muscle cells

189
Q

why are there many mitochondria between myofibrils

A

(each smaller than one sarcomere)
provide ATP for muscle contraction

190
Q

name of cytoplasm within muscle fibre

A

sarcoplasm

191
Q

what is each myofibril divided along its length into

A

repeating units called sarcomeres (contractile until of the muscle)

192
Q

what gives rise to the striped/striated appearance of muscle fibres

A

within the sarcomeres are 2 protein filaments and the overlap of these filaments gives rise to striped/striated appearances

193
Q

what are muscle fibres’ thin filaments

A

actin

194
Q

what are muscle fibres’ thick filaments

A

myosin

195
Q

what/where is the Z line

A

boundaries between sarcomeres (between actin filaments)

196
Q

what does I band contain

A

actin only

197
Q

what does H zone contain

A

myosin only

198
Q

what/where is the A band

A

overlap of actin and myosin (

199
Q

what does the M line contain

A

proteins which anchor the myosin filaments

200
Q

where is titin

A

along Z lines

201
Q

describe what happened to lengths when the muscle contracts

A

sarcomere gets shorter
I band decreases
H zone disappears
A band remains the same

202
Q

what do myosin filaments have

A

protein projections/cross bridges/ “bulbous heads” which extend towards the actin filaments

203
Q

what do myosin heads contain

A

an actin binding site
an ATP binding site (ATPase enzyme)

204
Q

myosin heads when muscle at rest?

A

not connected to the actin filaments
an ATP molecule is bound to the free end of each cross bridge

205
Q

what are actin filaments associated with

A

2 other proteins:
troponin
tropomyosin
(involved in the contraction process)

206
Q
A
207
Q

what are actin filaments made up of

A

2 actin chains twisted around each other

208
Q

what does troponin do

A

holds tropomyosin in place (binds to action tropomyosin and calcium)

209
Q

what does tropomyosin do

A

blocks binding sites for myosin head on actin

209
Q

step by step sliding filament mechanism

A

Ca2+ bind to troponin which changes shape. troponin and tropomyosin move away from myosin binding site so myosin heads (which have ADP and Pi attached) can bind to actin active site and muscle fibre can contract
conformational change in myosin head and it tilts from 90 to 45, which forces actin the move in relation to myosin (ADP and Pi released)
ATP now binds w myosin head
myosin head hydrolyses ATP to ADP and Pi, which provides the energy to released the myosin head from the actin.
the head detaches and flips away and returns to its original 90 position
then binds further along and process repeats

210
Q

what happens to sliding filament mechanism if ATP runs out

A

myosin heads do not detach
filaments cannot slide so become locked in position

211
Q

when does rigor mortis occur

A

48-60 hours after death

212
Q

what happens when myosin heads bend

A

actin and myosin filaments move past each other and muscle is shortened

213
Q

what happens during relaxation of muscle

A

Ca2+ returns to resting level (ATP used to pump Ca2+ back into sarcoplasmic)
active sites of actin are blocked

214
Q

what is a motor end plate

A

a highly excitable region of a muscle fibre

215
Q

where do motor neurones interact with muscles

A

neuromuscular junction/ motor end plate

216
Q

nervous stimulation of skeletal muscle

A

skeletal muscle is under the control of the voluntary NS
a single MN innervates many muscle fibres
each muscle fibre is controlled by a branch from only 1 MN

217
Q

step by step sequence of events in stimulation of a muscle fibre

A

an AP arrives
AP causes uptake of Ca2+ ions by MN
Ca2+ cause vesicles containing ACh to fuse w presynaptic membrane
ACh released and diffuses across synaptic cleft
ACh molecules bind w receptors in sarcolemma of muscle fibre, causing them to open Na+ channels
Na+ ions flood in, depolarising membrane and initiating AP which spreads along membrane down T-tubule (carried to centre of muscle fibres)
Ca2+ channels open so Ca2+ diffuse out of sarcoplasmic reticulum
Ca2+ bind to troponin, causing tropomyosin to move and expose the binding sites for myosin on actin filaments
myosin head binds (with ADP and Pi attached) so sliding filament mechanism occurs

218
Q

what happens when AP stops arriving at neuromuscular junction

A

T tubules no longer depolarised so Ca2+ channels in SR close
Ca2+ ions moved back into SR rapidly by transporter proteins
Ca2+ bound to troponin is released, so tropomyosin binds back to normal position covering myosin binding sites
myosin can no longer bind
muscle is relaxed

219
Q

similarities between synapses and neuromuscular junctions

A

NTs located in vesicles in presynaptic cytoplasm
arrival of ATP causes Ca2+ to move in and NT to move into cleft
NT diffuses across cleft and binds to complementary receptors on postsynaptic membrane
binding of NT results in opening of Na+ channels on post synaptic membrane
enzymes e.g. acetylcholinesterase present on the post synaptic membrane break down NT

220
Q

differences between synapses and neuromuscular junctions

A

S: post synaptic stimulation leads to AP in next neurone, NMJ: post synaptic stimulation leads to depolarisation of sarcolemma and contraction
S: neurone to neurone, NMJ: neurone to muscle
S: synaptic bulb rounded and small, NMJ: membrane of end plate has increased SA bc folded

221
Q

where does energy for muscle contraction come from (4 sources)

A

ATP
creatine phosphate
anaerobic metabolism
aerobic metabolism

222
Q

what system of energy supply dominates during tennis serve

A

ATP hydrolysis releases energy
ATP= small, soluble, relatively unstable so cannot be stored easily

223
Q

what system of energy supply dominates during 100m sprint

A

creatine phosphate
can supply more ATP to allow us to run for a few seconds

224
Q

what system of energy supply dominates during a 400m sprint (strenuous exercise)

A

anaerobic metabolism
cannot continue indefinitely bc of lactic acid buildup
also aerobic metabolism

225
Q

what system of energy supply dominates during marathon

A

aerobic metabolism
and anaerobic metabolism

226
Q

describe energy release during short burs of exercise e.g. tennis serve

A

ATP produced in respiration is required for the sliding filament mechanism
small amount of ATP are found in the sarcoplasm which can be hydrolysed
this ATP runs out within a few seconds
ATP to ADP, Pi and energy

227
Q

describe energy release during 100m sprint

A

replenishing ATP w creatine phosphate
most muscle fibres store creatine phosphate, a chemical that phosphorylates ADP to ATP
this reaction maintains the muscle’s supply of ATP during vigorous exercise
creatine phosphate is regenerated once energy becomes available

228
Q

what is the amount of ATP that creatine phosphate reaction can form limited by?
link to athletes

A

the initial concentration of creatine phosphate in the cell
for this reason, many athletes in sports that require rapid power output consume creatine supplements to increase the pool of immediately available ATP in their muscles

229
Q

describe energy release during strenuous exercise

A

anaerobic respiration dom (glycolysis) produces net 2 ATP
glucose ->2 lactic acid + 2NAD
NAD allows glycolysis to continue
if lactic acid builds up, muscles fatigue
(substrate level phosphorylation)

230
Q

describe energy release during marathon

A

aerobic respiration dom
glycolysis -> link reaction -> Krebs -> ETC
oxidative phosphorylation
greater yield of ATP than anaerobic resp

231
Q

when are slow twitch muscle fibres used

A

during endurance activities
bc they contract slowly and can work over long periods of time

232
Q

when are fast twitch muscle fibres used

A

for short bursts of activity
bc contractions are powerful and quick

233
Q

slow vs fast twitch muscle fibres: ATP

A

slow have more

234
Q

slow vs fast twitch muscle fibres: contraction time

A

slow= contract longer time
fast= short burst contraction

235
Q

slow vs fast twitch muscle fibres: fire____

A

slow= fire slowly
fast= fire rapidly

236
Q

slow vs fast twitch muscle fibres: respiration method

A

slow= aerobic
fast= anaerobic

237
Q

slow vs fast twitch muscle fibres: fatiguing

A

slow= fatigue slowly
fast= fatigue quickly

238
Q

why do fast twitch muscle fibres fatigue quickly

A

lactate produced as a by-product of aerobic respiration causes fast-twitch fibres to become fatigued quickly

239
Q

slow vs fast twitch muscle fibres: blood supply

A

slow= good blood supply
fast= poor blood supply

240
Q

slow vs fast twitch muscle fibres: mitochondria

A

slow= high numbers of mitochondria
fast= low numbers of mitochondria

241
Q

result of low number of mitochondria in fast-twitch muscle fibres

A

rely more on glycogen

242
Q

slow vs fast twitch muscle fibres: myoglobin

A

more myoglobin in slow so bright red
less myoglobin in fast so paler

243
Q

good blood supply, high no.s of mitochondria and more myoglobin in slow twitch muscle fibres helps w what?

A

help to maintain aerobic resp in the tissue
so slow twitch fibres are v slow to fatigue
HOWEVER, ATP gen is slower than in fast twitch fibres (contraction of slow twitch fibres is weaker)

244
Q

slow vs fast twitch muscle fibres: density of myofibrils

A

slow= low density myofibrils (low myosin ATPase activity)
fast= high density myofibrils

245
Q

slow vs fast twitch muscle fibres: diameter

A

slow= small diameter
fast= large diameter (thicker, more myosin)

246
Q

slow vs fast twitch muscle fibres: resistance to lactic acid

A

slow= low resistance to lactic acid
fast= high resistance to lactic acid

247
Q

how to measure fatigue

A

electrical activity of muscles can be investigated using an electromyograph (EMG)
the more powerful the contraction, the higher the amplitude
the amplitude decreases as the muscle fatigues

248
Q

suggest why a lack of ATP may lead to muscle rigidity

A

myosin heads cannot detach from actin (cross bridge not broken)
so filaments cannot slide and become locked in position
prevents relaxation/ muscle stays contracted

249
Q

muscles cannot elongate again (relax) without an ________
(EXPLAIN TOO)

A

antagonist
sometimes the antagonist is another muscle, sometimes it is elastic recoil air hydrostatic pressure in a container
e.g. elastic recoil & BP in blood and heart walls
e.g. elastic recoil in airways

250
Q

muscle fatigue definition

A

a decrease in maximal force or power production in response to contractile activity

251
Q

what is fatigue

A

when a muscle fibre is repeatedly stimulated, there is a decrease in tension and the muscle is said to be fatigued

252
Q

how does an increased conc of H+ ions lead to a reduction in the force of contraction of a muscle

A

as H+ conc increases, pH decreases so proteins in muscle denatured change shape
Ca2+ channels in sarcoplasmic reticulum change shape due to low pH-> can no longer allow Ca2+ to diffuse out into sarcoplasm
therefore insufficient Ca2+ to bind to troponin, so tropomyosin not moved so binding sites for myosin on actin filaments not exposed
less myosin heads can bind to actin , so less sliding filament mechanism ( conformational change in less myosin heads so less cross bridges form, so less heads bend so muscle shortens/contracts less)
power stroke strength decreased/ less power strokes
actin pulled past myosin w less force
H+ may denature any proteins e.g. actin/myosin

253
Q

suggest what might cause muscles to fatigue

A

lack of ATP: needed for Na+/K+ pumps, exocytosis, myosin head detachment and return to the 90 degree angle, pumping Ca2+ back into sarcoplasmic reticulum
lack of blood flow to the muscles
lack of O2 or glucose to muscle leads to lack of ATP
NT not released from presynaptic motor neurone
sarcolemma does not depolarise
damage to muscle fibres: prolonged/ intense muscle activity can cause damage to the muscle fibres, including micro-tease in muscle tissue. this damage can trigger an inflammatory response, leading to swelling and pain in the affected muscles, contributing to fatigue
accumulation of metabolic byproducts like H+ or lactic acid (these can disrupt normal cellular processes within muscle fibres, leading to fatigue. in addition, accumulation of H+ in muscle tissue can decrease pH of the muscle, further impairing muscle function)

254
Q

functions of cerebrospinal fluid (CSF), which surround the Braun and fills the central cavities

A

mechanical protection
removes excess heat/ cools brain
supplies O2

255
Q

advantage of cerebral cortex being highly folded

A

more neurones in given space
more processing power

biology (27 decks)

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