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OCR A level Biology HJ > Animal responses > Flashcards

Animal responses Flashcards

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1
Q

how and why do animals increase their chances of survival?

A
  • by responding to changes in their external environment, e.g. by avoiding harmful environments such as places that are too hot or too cold.
  • They also respond to changes in their internal environment to make sure that the conditions are always optimal for their metabolism (all the chemical reactions that go on inside them).
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2
Q

what is a stimulus?

A

any change in the internal and external environment.

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3
Q

what systems in animals need to be coordinated for animals to be able to respond to stimulus?

A

the nervous system, hormonal system and muscles.

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4
Q

what is the difference between receptors and effectors?

A

receptors detect stimuli and effectors bring about a response to a stimulus.

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5
Q

what do effectors include + give examples?

A

effectors include muscle cells and cells found in glands, e.g. the pancreas.

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6
Q

how do the receptors communicate with effectors?

A

via the nervous system or the hormonal (endocrine) system, or sometimes using both..

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7
Q

what are the systems that coordinate a response?

A

the nervous and hormonal systems.

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8
Q

what are the 2 main structural systems that the nervous system splits into?

A

-the central nervous system (CNS) and the peripheral nervous system.

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9
Q

what is the CNS made up of?

A

the brain and spinal cord.

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10
Q

what is the peripheral nervous system made up of?

A

neurones that connect the CNS to the rest of the body.

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11
Q

what are the 2 different functional systems of the peripheral nervous system?

A

the somatic and autonomic nervous system.

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12
Q

what does the somatic nervous system control + give examples?

A

-controls conscious activities -e.g. running and playing video games

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13
Q

what does the autonomic nervous system control + give examples?

A

-controls unconscious activities -e.g- digestion and heart rate

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14
Q

what is the autonomic nervous system split into + give examples?

A

the autonomic nervous system is split into the sympathetic and parasympathetic nervous systems, which have opposite effects on the body.

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15
Q

what is the sympathetic nervous system?

A

the sympathetic nervous system is the ‘fight or flight’ system that gets the body ready for action.

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16
Q

what does the sympathetic nerurones release?

A

sympathetic neurones release the neurotransmitter noradrenaline.

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17
Q

what is the parasympathetic system?

A

-its the ‘rest and digest’ system that calms the body down

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18
Q

what does the parasympathetic neurones release?

A

-they release the neurotransmitter acetylcholine

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19
Q

draw a diagram summarising the organisation of the nervous system

A

insert pic from page 353 CGP bottom

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20
Q

describe and state the function of cerebrum (5)

A
  • the cerebrum is the largest part of the brain.
  • its divided into 2 halves called cerebral hemispheres.
  • the cerebrum has a thin outer layer called the cerebral cortex, which is highly folded.
  • the cerebrum is involved in vision, hearing, learning and thinking.
  • controls voluntary actions, such as learning, memory, personality, and conscious thought.
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21
Q

describe and state the function of hypothalamus (5)

A
  • the hypothalamus is found just beneath the middle part of the brain.
  • it automatically maintains body temperature at the normal level
  • it also produces hormones that control the pituitary gland
  • monitoring the composition of blood plasma
  • regulatory centre for temperature and water balance
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22
Q

describe and state the function of medulla oblangata

A
  • the medulla oblangata is at the base of the brain, at the top of the spinal cord
  • it automatically controls breathing rate and heart rate
  • used in autonomic control, for example, it controls heart rate and breathing rate
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23
Q

describe and state the function of cerebellum

A
  • the cerebellum is underneath the cerebrum as it’s also a folded cortex
  • its important for muscle coordination, posture and coordination of balance
  • controls unconscious functions such as posture, balance and non-voluntary movement.
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24
Q

describe and state the function of pituitary gland

A
  • the pituitary gland is found beneath (and is controlled by) the hypothalamus.
  • it releases hormones and stimulates other gland, - e.g.- the adrenal glands, to release their hormones
  • stores and releases hormones that regulate many body functionsF
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25
Q

label a diagram of the structure of the brain

A

insert pic from page 354 CGP

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26
Q

what is a reflex and why does it happen? + Benefit

A
  • a reflex action is where the body responds to a stimulus without making a conscious decision to respond.
  • this sis because the pathways of communication doesn’t involve conscious parts of the brain- instead it goes through unconscious parts of the brain or the spinal cord
  • because you don’t have to spend time deciding how to respond, information travels really fast from receptors to effectors.
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27
Q

why are reflex actions protective?

A

they help organisms to avoid damage to the body because the response happens so quickly

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28
Q

what are the 3 neurones involved in the pathway of communication linking receptors to effectors in a reflex action typically?

A
  • a sensory neurone
  • a relay neurone
  • a motor neurone
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29
Q

draw a flow diagram showing the pathway of nervous communication in a reflex action

A

sensory motor
neurone neurone
^ ^
| |
stimulus–>receptors–> CNS –>effectors–>response
(relay neurone in unconscious of brain or spinal cord)y

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30
Q

describe the blinking reflex and write a 5 step process on how this occurs

A

+when your body detects something that could damage your eye, you automatically blink- you quickly close your eyelid to protect you eye, then open your eyelid again.

  • STIMULUS= something touches your eye
  • RECEPTORS= sensory nerve endings in the cornea (front part of the eye) detect the touch stimulus. A nerve impulse is sent along the sensory neurone to the relay neurone in the CNS.
  • CNS= the impulse is then passed from the relay neurone to motor neurones.
  • EFFECTORS= the motor neurones send impulses to the orbicularis oculi muscles that move your eyelids
  • RESPONSE= these muscles contract causing your eyelids to close quickly and prevent your eye from being damaged
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31
Q

describe the knee- jerk reflex and write a 5 step process on how this occurs

A

+the knee-jerk reflex works to quickly straighten your leg if your body detects your quadriceps is suddenly stretched. It helps to maintain posture and balance.

  • STIMULUS= your quadriceps muscle is stretched.
  • RECEPTORS= stretch receptors in quadriceps muscle detect that the muscle is being stretched. A nerve impulse is passed along a sensory neurone.
  • CNS= the sensory neurone communicates directly with a motor neurone in the spinal cord (there is no relay neurone involved).
  • EFFECTORS= the motor neurone carries the nerve impulse to the quadriceps muscle.
  • RESPONSE= the quadriceps muscle contracts so the lower leg moves forward quickly
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32
Q

what happens in the ‘fight or flight’ response? (5)

A

1-nerve impulses form sensory neurones arrive at the hypothalamus, activating both the hormonal (endocrine) system and the sympathetic nervous system.

2-the pituitary gland is stimulated to release a hormone called ACTH.

3- this causes the cortex of the adrenal gland to release steroidal hormones, which have a range of effects on the body, helping it to respond to stress both in the short and long- term.

4-the sympathetic nervous system is activated, triggering the release of adrenaline from the medulla region of the adrenal gland.

5-the sympathetic nervous system and adrenaline produce a faster response than the hormones secreted by the cortex of the adrenal glad

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33
Q

what are the 6 effects of the flight of flight response?

A

1- heart rate is increased and the heart contracts withe more force, causing blood to be pumped around the body faster.

2- the muscles around the bronchioles relax, causing the airways to widen, so breathing is deeper.

3-the intercostal muscles and diaphragm also contract faster and with more strength, increasing the rate and depth of breathing

4-glyogen is converted into glucose via glycogenolysis so more glucose is available for muscles to respire.

5-arterioles in the muscles supply the heart, lungs and skeletal muscles causing them to dilate- so blood is diverted from the skin and gut to the heart, lungs and skeletal muscles (e.g. in the legs), making them ready for action.

6-erector pili muscles in the skin contact- this makes hair stand on end so the animals looks bigger

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34
Q

Describe the sino- atrial node (SAN) and its function

A
  • its a small mass of tissue in the wall of he right atrium of the heart called the Sino-atrial node (SAN).
  • the SAN generates electrical impulses that cause the cardiac muscles to contract.
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35
Q

how is the SAN impulses controlled by the nervous system?

A

the rate at which the SAN fires (i.e. heart rate) is unconsciously controlled by the cardiovascular centre in the medulla oblongata (a structure in the brain).

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36
Q

why do animals need to be able to alter their heart rate?

A

-animals need to alter their heart rate to respond to internal stimuli, e.g. to prevent fainting due to low blood pressure or to make sure the heart rate is high enough to supply the body with enough oxygen.

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37
Q

what are internal stimuli detected by?

A
  • pressure receptors

- chemical receptors

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38
Q

what are barorecepetors and what do they do? Where Are they located?

A
  • there are pressure receptors called baroreceptors in the aorta and the carotid arteries.
  • They’re stimulated by high and low blood pressure.
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39
Q

what are chemoreceptors and what do they do? Where Are they found?

A
  • there are chemical receptors called chemoreceptors in the aorta, the carotid arteries and in the medulla oblongata.
  • They monitor the oxygen level in the blood and also CO2 and pH (which are indicators of O2 level).
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40
Q

where are nerve impulses from receptors sent to?

A
  • nerve impulses form receptors are sent to he cardiovascular centre along sensory neurones.
  • The cardiovascular centre processes the information and sends impulses to the SAN along motor neurones.
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41
Q

how does the heart rate change in response to high blood pressure?

A
  • baroreceptors detect high blood pressure and send impulses along sensory neurones to the cardiovascular centre, which sends impulses along parasympathetic neurones.
  • These secrete acetylcholine, which binds to receptors on the SAN.
  • This causes the heart rate to slow down in order to reduce blood pressure back to normal.
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42
Q

how does the heart rate change in response to low blood pressure?

A
  • baroreceptors detect low blood pressure and send impulses along sensory neurones to the cardiovascular centre, which sends impulses along sympathetic neurones.
  • These secrete noradrenaline, which binds to receptors on the SAN.
  • This causes the heart rate to speed up in order to increase blood pressure back to normal.
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43
Q

how does the heart rate respond to high blood O2, low CO2 or high blood pH levels?

A
  • chemoreceptors detect chemical changes in the blood and send impulses along sensory neurones to the cardiovascular centre, which sends impulses along parasympathetic neurone.
  • These secrete acetylcholine, which binds to receptors on the SAN.
  • this causes the heart rate to decrease in order to return oxygen, carbon dioxide and pH levels back to normal.
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44
Q

how does the heart rate respond to low blood O2, high CO2 or low blood pH levels?

A
  • chemoreceptors detect chemical changes in the blood and send impulses along sensory neurones to the cardiovascular centre, which sends impulses along sympathetic neurones.
  • these secrete noradrenaline, which binds to receptors on the SAN.
  • This causes the heart rate to increase in order to return oxygen, CO2 and pH levels back to normal.
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45
Q

how does the hormonal system help the heart rate respond to the an external threat?

A
  • when an organism is threatened the adrenal glands release adrenaline.
  • Adrenaline binds to specific receptors in the heart.
  • This causes the cardiac muscles to contract more frequently and with more fence, so the heart rate increases and the heart pumps more blood.
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46
Q

how do you measure your heart rate?

A

1-find your pulse in your wrist by placing your index and middle finger where the base of your thumb meets your forearm.

2-count the number of beats in 15 seconds

3-multiply by 4 to get the number of beats per minute

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47
Q

what is the effect of exercise on heart rate?

A
  • when you exercise, your rate of respiration increases.
  • this reduces the pH and the oxygen level in the blood and increases and CO2 level.
  • chemoreceptors detect these changes and cause heart rate to increase to bring the levels back to normal.
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48
Q

write a 3 step methods describing how to measure the effect of exercise on your heart rate

A

1- measure your heart rate at rest and record it in a table

2-do some gentle exercise, such as stepping on and off a step for 5 minutes. Immediately afterwards, measure your heart rate again.

3-return to a resting position. Measure your heart rate every minute until it returns to the starting rate. Record how long it takes to return to normal.

=if you wanted to find out whether this exercise caused a significant increase in hart rate you could collect more results (e.g. by repeating exactly the same experiment using other people) and then carrying out a statistical test

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49
Q

what is another way of monitoring heart rate?

A

you could sue an electronical heart rate monitor instead.

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50
Q

how does an electronic heart rate monitor work?

A
  • there are different types of electronic heart rate monitors, but the ones you’re likely to use consist of a chest strap and a wrist monitor.
  • the chest strap contains electrodes (sensors) which detect the electrical activity of the heart (through the skin) as it beats.
  • the data is picked up by the electrodes and then transmitted wirelessly to the wrist monitor, which displays the data as a heart rate in beats per minute (bpm).
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51
Q

what are some advantages of using an electronic heart rate monitor over manually taking your pulse?

A

-E.g.- a monitor can measure your heart rate as you are exercising and keep a continual record of how it changes, whereas manual pulse measurements must be done at intervals.

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52
Q

what is the student t-test?

A

its a statistical test used to find out whether there is a significant difference in the means of 2 data sets

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53
Q

what is done with the value obtained from the student t-test?

A

-the value obtained is compared to a critical value, which helps you decide how likely it is that the results or ‘differences in the means’ were due to chance.

54
Q

what is the student t-test used for?

A

it can be used to determine whether a particular variables, such as exercise, has a significant effect on heart rate or whether any results observed were just due to chance.

55
Q

what is the role of the CNS (brain and spinal cord)?

A
  • coordinates muscular movement- it receives sensory information and decides what kind of response is needed.
  • If the response needed is movement, he CNS sends nervous impulses along motor neurones to tell skeletal muscles to contract.
  • Skeletal muscle is the type of muscle you use to move, e.g.- the biceps and triceps move the lower arm.
56
Q

what else is the skeletal muscle referred to as?

A

-striated, striped or voluntary muscle

57
Q

what type of muscle is a skeletal muscle?

A

it’s the type of muscle you use to move, e.g.- the biceps ad triceps move the lower arm

58
Q

what is the skeletal muscle made up of + describe the structure?

A
  • skeletal muscle is made up of large bundles of long cells, called muscle fibres.
  • the cell membrane of muscle fibre called the sarcolemma.
  • bits of the sarcolemma fold inwards across the muscle fibre and stick into the sarcoplasm (a muscle cell’s cytoplasm).
  • these folds are called transverse (T) tubules and they help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre.
59
Q

what is the sacroplasmic reticulum?

A

-its a network of internal membranes which runs through the sarcoplasm

60
Q

what is the role of the sarcoplasmic reticulum?

A

the sarcoplasmic reticulum stores and releases calcium ions that are needed for muscle contraction.

61
Q

why do muscle fibres have lots of mitochondria?

A

to provide the ATP that’s needed for muscle contraction

62
Q

what structures do muscle fibres have?

A
  • lots of mitochondria
  • many nuclei (multinucleate)
  • myofibrils (cylinder organelles) = myofibrils are made up of proteins and are highly specialised for contraction.
63
Q

describe myofibrils

A

(cylinder organelles) = myofibrils are made up of proteins and are highly specialised for contraction.

-myofibrils contain bundles of thick and thin myofilaments that move past each other to make muscles contract

64
Q

what are myofilaments made up of?

A

-the thick myofilaments are made of the protein myosin and the thin myofilaments are made of the protein actin.

65
Q

what would you see when looking at a myofibril under an electron microscope?

A

you’ll see a pattern of alternating dark and light bands

66
Q

what do the dark and light bands from the myofibrils contain?

A
  • dark bands contain the thick myosin filaments and some overlapping thin actin filaments- these are called A- bands.
  • light bands contain thin actin filaments only- these are called I- bands.
67
Q

what are myofibrils made up of?

A

a myofibril is made up of many short units called sacromeres.

68
Q

what are the ends each sarcomere marked with?

A

with a Z- line

69
Q

what is the middle of the sarcomere called?

A

the M- line which is the middle of the myosin filaments

70
Q

what is the zone around the M-line called and what does it contain?

A

around the M-line is the H-zone.

the H-zone only contains myosin filaments

71
Q

draw and label a diagram of the structure of a sarcomere- a unit of a myofibrils

A

insert pic from page 364 CGP top

72
Q

how does the sliding filament model explain muscle contarctions?

A
  • this is where myosin and actin filaments slide over one another to make the sarcomeres contract- the myofilaments themselves don’t contract.
  • the simultaneous contraction of lots of sarcomeres means the myofibrils and muscle fibres contract.
  • sarcomeres return to their original lengths as the muscle relaxes.
73
Q

draw and label a diagram of the sliding filament model

A

insert pic from page 364 CGP bottom

74
Q

describe the structure of the myosin filaments

A
  • myosin filaments have globular heads that are hinges, so they can move back and forth.
  • each myosin head has a binding site for actin and a binding site for ATP
75
Q

describe the structure of the actin filaments

A
  • actin filaments have binding sites for myosin heads, called actin-myosin binding sites.
  • 2 other proteins called tropomyosin and troponin are bound between actin filaments.
  • these proteins are attached to each other (troponin holds tropomyosin in place) and they help myofilaments move past each other.
76
Q

draw the structure of myosin and actin filaments

A

insert pic from page 365 CGP bottom

77
Q

describe the binding sites in resting muscles

A
  • for myosin and actin filaments to slide past each other, the myosin head needs to bind to the actin- myosin binding site on the actin filaments.
  • in a resting (unstimulated) muscle the actin- myosin binding site is blocked by tropomyosin.
  • this means myofilaments can’t slide past each other because the myosin heads can’t bind to the actin filaments.
78
Q

what happens with the muscle contraction after the arrival of an action potential?

A

1-when an action potential from a motor neurone stimulates a muscle cell, it depolarises the sarcolemma.

2-depolarisation spreads down the T-tubules to the sarcoplasmic reticulum.

3-this causes the sarcoplasmic reticulum to release stored calcium ions (Ca2+) into the sarcoplasm.

4-this influx of calcium ions into the sarcoplasm triggers muscle contraction.

5-calcium ions bind to troponin, causing it to change shape.

6-this pulls the attached tropomyosin out of the actin- myosin binding site on the actin filament.

7-this exposes the binding site, which allows the myosin head to bind.

8-the bind formed when a myosin head binds to an actin filament is called an actin-myosin cross bridge.

79
Q

describe the movement of the actin filament

A

1-calcium ions also activate the enzyme ATPase, which breaks down ATO (into ADP + Pi) to provide the energy needed for muscle contraction.

2-the energy released form ATP moves the myosin head to the side, which pulls the actin filament along in a kind of rowing actin.

80
Q

describe the process of the breaking of the cross bridge

A

1-ATP also provide the energy to beak the actin- myosin cross bride, so the myosin head detaches from the actin filament after it’s moved.

2-the myosin head then returns to it’s starting position, and reattaches to a different binding site further along the actin filament.

3-a new actin-myosin cross bride is formed and the cycle is repeated (attach, move, detach, reattach to new binding site)

4-many actin-myosin cross bridges form and break very rapidly, pulling the actin filament along-which shortens the sarcomere, causing the muscle to contract.

5-the cycle will continue as long as calcium ions are present and bound to troponin.

81
Q

describe the process of the actin-myosin returning to resting state

A

1-when the muscle stops being stimulated, calcium ions leave their binding sites on the troponin molecules and are moved by active transport back into the sarcoplasmic reticulum (this needs ATP too).

2-the troponin molecules return to their original shape, pulling the attached tropomyosin molecules with them.

3-this means the tropomyosin molecules block the actin-myosin binding sites again.

4-muscles aren’t contracted because no myosin heads are attached to actin filaments (so there are no actin-myosin cross bridges).

5-the actin filaments slide back to their relaxed position, which lengthens the sarcomere.

82
Q

draw a flow diagram of:
1-the structure of myosin and actin filaments
2-actin and myosin filaments in resting muscle
3-formation of an actin-myosin cross bridge
4-movement of the myosin head
5-myosin head forms a new actin-myosin cross bridge
6-blocking of the actin-myosin binding sites as the muscle returns to its resting state

A

insert pictures from pages365,366 and 367 CGP

83
Q

in aerobic respiration, how is ATP made and what are the conditions for aerobic respiration?

A
  • most ATP is generated via oxidative phosphorylation in the cell’s mitochondria.
  • aerobic respiration only works when there’s oxygen so it’s good for long periods of low-intensity exercise, e.g. a long walk
84
Q

in anaerobic respiration, how is ATP made?

-what is the end product and what happens to it?

A
  • ATP is made rapidly by glycolysis

- the end product of glycolysis is pyruvate, which is converted to lactate by lactate fermentation

85
Q

what is a disadvantage of anaerobic respiration?

A

Lactate can quickly build up in the muscles and cause muscle fatigue (where the muscles can’t contract as forcefully as they could do previously).

-Anaerobic respiration is good for short periods of hard exercise, e.g. a 400m sprint

86
Q

how does ATP-creatine phosphate (ATP-CP) system work?

A
  • ATP is made by phosphorylating ADP- adding a phosphate group taken from CP.
  • ADP + CP —> ATP + C (creatine)
  • CP is stored inside cells and the ATP-CP system generates ATP very quickly.
  • CP runs out after a few seconds so it’s used during short bursts of vigorous exercise, e.g.- a tennis serve.
  • The ATP-CP system is anaerobic (is doesn’t need oxygen) and it’s alactic (it doesn’t form any lactate).
87
Q

what are the 3 ways that ATP is continually generated as ATP gets quickly used up in muscle contractions?

A

1-aerobic respiration
2-anaerobic respiration
3-ATP-creatine phosphate (ATP-CP) system

88
Q

what different reasons are muscle fibres used for?

A
  • some muscle fibres contract very quickly- they’re used for speed and strength but fatigue (get tired) quickly.
  • some muscle fibres contract slowly and fatigue slowly- they’re used for endurance and posture
89
Q

why involuntary muscle also called smooth muscle?

A

involuntary muscle is also called smooth muscle because it doesn’t have the striped appearance of voluntary muscle.

90
Q

where is involuntary muscle (smooth muscle) found?

A

-it’s found in the walls of your hollow internal organs, e.g. the gut, the blood vessel

91
Q

why do your gut smooth muscles contract?

A

to move food along (peristalsis)

92
Q

why do your blood vessel smooth muscles contract?

A

to reduce the flow of blood

93
Q

describe the structure of involuntary muscle (smooth muscle)?

A
  • each muscle fibre is uninucleate (has one nucleus)
  • the muscle fibres are spindle- shaped with pointed ends, and they’re only about 0.2mm long.
  • The muscle fibres contract slowly and don’t fatigue
94
Q

what does it mean for cardiac muscles (heart muscles) to be myogenic)?

A

cardiac muscle contracts on its own

95
Q

where is cardiac muscle found?

A

it’s found in the walls of your heart and its unction is to pump blood around the body

96
Q

what is cardiac muscles made of?

A

it’s made of muscle fibre connected by intercalated discs, which have low electrical resistance so nerve impulses pass easily between cells

97
Q

why are muscle fibres branched?

A

the muscle fibres are branched to allow nerve impulses to spread quickly through the whole muscle

98
Q

describe the structure of cardiac muscles

A
  • each cardiac muscle fibre is uninucleate.
  • the muscle fibres are shaped like cylinders and they’re about 0.1mm long
  • the muscle fibres contract rhythmically and don’t fatigue
99
Q

what doe you see under a microscope when looking at a cardiac muscle?

A

you would see some cross-striations under a microscope but the striped pattern isn’t as strong as it is in skeletal muscle

100
Q

what is a neuromuscular junction?

A

a neuromuscular junction is a synapse between a motor neurone and a muscle cell

101
Q

what is the similarity of neuromuscular junctions and synapses?

A

neuromuscular junctions work in the same way as synapses between neurones- they release neurotransmitter, which trigger depolarisation in the postsynaptic cell

102
Q

what does depolarisation of a muscle cell cause?

A

depolarisation of a muscle cell always causes it to contract (if the threshold level is reached)

103
Q

what neurotransmitter do neuromuscular junctions use and what does it do?

A

neuromuscular junctions use the neurotransmitter acetylcholine (ACh), which binds to receptors called nicotinic cholinergic receptors

104
Q

what does Acetylcholinesterase (AChE)?

A

Acetylcholinesterase (AChE) stored in clefts on the postsynaptic membrane is released to break down acetylcholine after use

105
Q

draw a diagram of the structure of a neuromuscular junction

A

insert pic from page 371 CGP

106
Q

what effects do drug have on muscles?

A
  • sometimes a chemical (e.g. a drug) may block the release of the neurotransmitter or affect the way it binds to the receptors on the postsynaptic membrane.
  • this may prevent the action potential from being passed on to he muscle, so the muscle won’t contract.
  • chemicals that affect the action of neurotransmitters at neuromuscular junctions can be fatal if they affect the muscles involved in breathing, e.g.- the diaphragm and intercostal muscles.
  • if they can’t contract, ventilation can’t take place and the organism can’t respire automatically
107
Q

what effect does Pancuronium bromide have on muscles?

A
  • Pancuronium bromide is a non- depolarising, neuromuscular blocking drug.
  • it competes against ACh for the nicotinic cholinergic receptors binding to them so that at he action of ACh is blocked and the muscle cell doesn’t depolarise.
  • it is used during surgery because it relaxes the muscles.
  • the action of Pancuronium bromide can be reversed by inhibiting the action of AChE so that the concentration of ACh increases.
  • this means it can out-compete the drug for available nicotinic cholinergic receptors.
108
Q

how do you investigate muscle contraction and fatigue by monitoring the electrical activity that occurs?

A
  • muscles contact in response to nervous impulses- these are electrical signals
  • electrical signals i muscles can be detected by electrodes (sensors) placed on the skin.
  • the electrodes are connected to a computer to allow the electrical signals to be monitored.
  • the procedure is called electromyography and the reading it generates is called an electromyogram (EMG).
109
Q

write the 7 step method for an investigation into muscle contraction and fatigue by monitoring the electrical activity that occurs?

A

1- first o fall you ned to attach two electrodes to places on the muscle that you want to record from- in this e.g. we will use the biceps muscle in the arm. A 3rd electrode goes on an inactive point (such as the bony wrist area) to act as a control.

2- switch off any other electrical equipment that you don’t need as this generates ‘noise’ that interferes with the electrical signal form the muscle.

3- connect the electrodes to an amplifier and a computer. (An amplifier increases the strength of the electrical signals from the muscle.)

4- keep the muscle relaxed. You should see a straight line on the electromyogram.

5- then contract the muscle by bending your arm. you should see spikes in the graph as motor units are activated to contract the muscle.

6- if you then lift a weight, the amplitude (height) of the trace on the graph will increase- there are more electrical; signals because more motor units are required to lift the weight.

7- if you continue to hold the weight, your muscle will begin to fatigue. This means that the muscle can no longer contract as forcefully as it could previously. On the electromyogram you will see the amplitude of the trace increase further. This is because you brain is trying to activate more motor units to generate the force needed to hold the weight up.

110
Q

draw and label a diagram of an electromyogram (EMG)- the regions

A

insert pic from page 372 CGP bottom

111
Q

draw a diagram of the structure of the human brain

A

insert pic from page 354 CGP

112
Q

what happens to a person with a damaged cerebellum?

A

they suffer from jerky and uncoordinated movement

113
Q

what 2 sections is the pituitary gland divided into?

A
  • anterior pituitary (front section)

- posterior pituitary (back section)

114
Q

what is the function of the anterior pituitary?

A

produces 6 hormones including follicle- stimulating hormone (FSH), which is involved in reproduction and growth hormones

115
Q

what is the function of the posterior pituitary ?

A

stores and releases hormones produced by the hypothalamus, such as ADH involved in urine production

116
Q

what is the generic chain of events between the stimulus and the response?

A

1-receptor= detects stimulus and creates an action potential in the sensory neurone.

2- sensory neurone= carries impulse to spinal cord

3- relay neurone= connects the sensory neurone to the motor neurone within the spinal cord or brain

4-motor neurone= carries impulse to the effector to carry out the appropriate response

117
Q

how do you measure reaction time?

A
  • when a person catches a falling object, at least part of this response is a reflex reaction.
  • measuring the time taken to catch a falling object can interfere be used to measure a person’s reaction time.
  • to measure the reaction time, a suitable scale is placed onto the ruler which converts the distance dropped by the ruler into a reaction time.
  • one investigation which an be carried out using this approach is to measure the effect of caffeine concentration on a person’s reaction time.
  • when carrying out this investigation, a researcher may choose to give a placebo caffeine drink to some of the people being tested.
  • this is a drink labelled as a caffeine drink, but contains no caffeine.
118
Q

what are 4 ways that reflexes increase your chance of survival?

A
  • BEING INVOLUNTRAY RESPONSES- the decision-making regions pf the brain aren’t involved, therefore the brain is able to deal with more complex responses. It prevents the brain from being overloaded with situations in which the response is always the same
  • NOT HAVING TO BE LEARNT- they’re present at birth and therefore provide immediate protection.
  • EXTREMEMLY FAST- the reflex arc i very short. it normally only involves 1 or 2 synapses, which are the slowest part of nervous transmission
  • many reflexes are what we would consider everyday actions, such as those which keep us upright (and thus not falling over), and those which control digestion
119
Q

name a describe the 3 types of muscles in the body

A
  • SKELETAL MUSCLE- skeletal muscles make up the bulk of body muscle tissue. These are the cells responsible for movement, e.g.- the biceps and triceps.
  • CARDIAC MUSCLE- cardiac muscle cells are found only in the heart. These cells are myogenic, meaning they contract without the need for a nervous stimulus, causing the heart to beat in a regular rhythm.
  • involuntary muscle (smooth muscle)- involuntary muscle cells are found in many parts of the body- e.g.-in the walls of hollow organs such as the stomach and bladder. They are also found in the walls of the blood vessels and the digestive tract, where through peristalsis they move along the gut
120
Q

what is the difference in fibre appearance between skeletal, cardiac and involuntary muscle?

A 
skeletal= striated
cardiac= specialised striated 
involuntary= non-striated
121
Q

what is the difference in control type between skeletal, cardiac and involuntary muscle?

A 
skeletal= conscious (voluntary)
cardiac= involuntary
involuntary= involuntary
122
Q

what is the difference in arrangement appearance between skeletal, cardiac and involuntary muscle?

A 
skeletal= regularly arranged so muscle contracts in 1 direction
cardiac= cells branch and interconnect resulting in simultaneous contraction
involuntary= no regular arrangement- different cells can contract in different direction
123
Q

what is the difference in contraction speed appearance between skeletal, cardiac and involuntary muscle?

A 
skeletal= rapid
cardiac= intermediate
involuntary= slow
124
Q

what is the difference in length of contraction appearance between skeletal, cardiac and involuntary muscle?

A 
skeletal= short
cardiac= intermediate
involuntary= can remain contracted for a relatively long time
125
Q

what is the difference in structure appearance between skeletal, cardiac and involuntary muscle?

A

skeletal= muscles showing cross striations are known as striated on striped muscles. Fibres are tubular and multinucleated.

cardiac= cardiac muscle does show striations but they are much fainter than those in skeletal muscle. Fibres are branched and uninucleated.

involuntary= muscles showing no cross striations are called non-striated or unstriped muscles. Fibres are spindle shaped and uninucleated.

126
Q

describe the structure of actin

A

-the thinner filament. It consists of 2 strands twisted around each other

127
Q

describe the structure of myosin

A

-the thicker filaments. It consists of long rod- shaped fibres with bulbous heads that project to one side.

128
Q

describe the structure and light bands

A

these areas appear light as they are the region where the actin and myosin filaments do not overlap. (they are also known as isotopic bands or I- bands

129
Q

describe the structure of dark bands

A

these areas appear dark because of the presence of thick myosin filaments. The edges are particularly dark as the myosin is overlapped with actin. (They are also known as anisotropic bands or A-bands.)

130
Q

describe the structure of the Z-line

A

this is a line found at the centre of each light band. The distance between adjacent Z-lines is called a sarcomere. The sarcomere is the functional unit of the myofibril. When a muscle contracts the sarcomere shortens.

131
Q

describe he structure of the H-zone

A

this is a lighter coloured region found in the centre of each dark band. Only myosin filaments are present at this point. When the muscle contracts the H-zone decreases.

OCR A level Biology HJ (23 decks)

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