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OCR A level bio > Animal Responses > Flashcards

Animal Responses Flashcards

1
Q

What two are the two systems that the nervous systems split into

A

CNS- made of brain and spinal cord

Peripheral nervous system- Made up of what connected CNS to rest of body

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2
Q

What are two systems of peripheral nervous system

A

Somatic NS: Controls conscious activities e.g. running and planning video games

Autonomic NS: Controls unconscious activities e.g. digestion

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3
Q

What are two divisions of the autonomic nervous system

A

Sympathetic nervous system: gets the body ready for action- fight or flight

Parasympathetic NS- calms the body down

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4
Q

What do sympathetic nerves do

A

Raise heart rate by secreting noradrenaline

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5
Q

What do parasympathetic nerves do

A

Slows heart rate by secreting acetylcholine

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6
Q

Difference between anterior pituitary and posterior pituitary gland

A

Posterior pituitary only stores and releases hormones sent from the hypothalamus such as ADH and oxytocin. Anterior pituitary produces and releases hormones

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7
Q

Where is cerebrum found in brain and whats its function

A

Largest part of brain
Divided into two parts- cerebral hemispheres

Cerebral cortex is a thin outer layer which is folded
Cerebrum is involved in hearing, vision, learning and thinking

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8
Q

Where is hypothalamus and whats its function

A

Found beneath the middle part of the brain. It monitors temperature of blood flowing through it.

Produces hormones that control pituitary gland

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9
Q

Where is the medulla oblong at a in brain and its function

A

It’s at the base of the brain, at the top of the spinal cord
Automatically controls breathing and heart rate

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10
Q

Where is cerebellum and its function

A

Underneath the cerebrum and has a folded cortex

Important for muscle coordination, posture and coordination of balance

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11
Q

What is a reflex

A

Responses to the environment that are not processed by the brain

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12
Q

What are two effectors in the blinking reflex

A

Orbicularis oculi muscle- pulls eyes inward

Superior levator palpebrae- lowers the eyelid

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13
Q

How does the NS help control heart rate

A

SAN generates electrical impulses that cause the cardiac muscles to contract
Rate at which SAN fires (HR) is unconsciously controlled by medulla
Need to alter HR to respond to internal stimuli e.g. prevent fainting due to low blood pressure
Stimuli detected by pressure receptors and chemical receptors

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14
Q

How does the medulla respond to high/low pressure

A

High blood pressure: detected by baroreceptor. Impulses sent to the medulla which sends impulses across vagus nerve. This secretes acetylcholine, binding to receptors on SAN

Low blood pressure- detected by baroreceptor.
Impulses sent to the medulla which sends impulses along the accelerator nerve. Secretes noradrenaline, binds to receptors on the SAN

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15
Q

How does medulla respond to high o flow PH levels

A

High PH: Detected by chemoreceptors- impulses sent to the medulla which sends impulses along the vagus nerve. Secretes acetylcholine, binds to receptors on the SAN

Low PH: Detected by chemoreceptors. Impulses are sent to the medulla which sends impulses along the accelerator nerve. Secretes noradrenaline, binds to receptors on SAN

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16
Q

What is T test for

A

Whether a significant difference between means of 2 data sets

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17
Q

What’s the impact of adrenaline

A

Increases
Decreases blood flow to gut by vasoconstriction
Increase blood flow to heart and muscles by vasodilation

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18
Q

What are skeletal muscles made from

A

Muscle fibres- Cell membrane of this is called sarcolemma
Bits of sarcolemma fold inwards across muscle fibres and stick into the sacroplasm- which are called Transverse Tubules and help spread electrical impulses throughout the sarcoplasm so they reach all parts of muscle fibre

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19
Q

What is the sarcoplasmic reticulum

A

Network of internal membranes, stores and releases calcium ions needed for muscle contraction

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20
Q

What organelle do muscle fibres have which is important

A

Have a lot of mitochondria to provide ATP thats needed for muscle contraction

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21
Q

What are myofibrils

A

Long, cylindrical organelles which are made of proteins and highly specialised for contraction

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22
Q

What are microfibrils made up of

A

Contain bundles of thick and thin myofilaments that move past each other to make muscles contract

Thick myofilaments are made of the protein myosin

Thin myofilaments are made up of the protein actin

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23
Q

What does a microfibril look like under a microscope

A

Dark bands contain thick myosin filaments and overlapping thin actin filaments- A bands

Light bands contain thin actin filaments only- L bands

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24
Q

What are sacromeres

A

Short units which make up microfibrils

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25
Q

What is the Z line

A

Line which marks the end of a sarcomere

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26
Q

What can be found in the middle of each sarcomere

A

M line- middle of myosin filaments

Around the M line is the H zone

H zone only contains myosin filaments

27
Q

What’s the sliding filament theory

A

Myosin and actin filaments slide over each other to make sarcomere a contract

Simultaneous contraction of lots of sacromeres means that the myofibrils and muscle fibres contract

Sacromeres return to original length as muscle relaxes

28
Q

What happens to the different bands in sarcomere as it contracts

A

A band stays same

L band gets shorter

H zone gets shorter

29
Q

What are some features of myosin filaments

A

Myosin filaments have globular heads that are hinged, so can move back and forth
Each myosin head has a binding site for actin and binding site for ATP
Actin myosin binding sites

Tropomyosin and troponin are found between actin filaments

30
Q

What happens to binding sites of resting muscles

A

Actin- myosin binding site is blocked by tropomyosin, which is held in place by troponin

So myofilaments can’t slide past each other because the myosin heads can’t bind to actin-myosin binding site in actin filaments

31
Q

How does an action potential trigger muscle contraction

A

Action potential from a motor neurone stimulates a muscle cell, depolarising the sarcolemma, which depolarising spreads down T tubules to sarcoplasmic reticulum

Causes sarcoplasmic reticulum to release stores Ca2+ ions into sarcoplasm
These bind to troponin causing it to change shape, pulls attached tropomyosin out of the binding site on the actin

Exposes the binding site allowing the myosin head t bin- this bind formed when a myosin head binds to actin filament- actin-myosin cross bridge.

Ca2+ ions also activate the enzyme ATPase which breaks down ATP to provide energy- this moves the myosin head which pulls the actin

Myosin head detached once moved and reattached

32
Q

What happens when the muscle stops being stimulated

A

Calcium ions leave binding sites on the troponin and are moved by active transport back to sarcoplasmic reticulum

Troponin molecules return to their original shape, pilling attached tropomyosin molecules with them

Means the tropomyosin molecules block the actin myosin binding sites again

Actin filaments slides back to relaxed position which lengthens the sarcomere

33
Q

What is a neuromuscular junction

A

Synapse between motor neurone and muscle cell

Use transmitter acetylcholine to bind to nicotine cells cholinergic receptors

Same way as synapses which release neurotransmitter and trigger depolarisation in postsynaptic cell

Causes it to contract

34
Q

What happens when a chemical blocks the release of a neurotransmitter or blocks the receptor site

A

May prevent the action potential from being passed onto the muscle so the muscle won’t contract

Could be fatal if effects the muscles involved in breathing
If can’t contract ventilation can’t occur and can’t dealire anaerobic

35
Q

What is the structure and function of skeletal muscle

A

Control is conscious
Made from muscle fibres with many nuclei
Cross satiations on a microscope
Some contract quickly and used for speed and strength but fatigue quickly, and some slow which fatigue slow and used for endurance and posture

36
Q

What’s the structure and function of involuntary muscle

A

Also called smooth muscle
Controlled unconsciously
Found in walls of hollow internal organs, e.g. in gut contracts t move food along
One nucleus
Slowly and don’t fatigue

37
Q

How could you monitor muscle fatigue

A

Monitor electrical signals and musk as contract in response to these
Can be detected by electrodes placed on the skin
Connected to a computer to allow electrical signals to be monitored
Is called electromyography

38
Q

What are baroreceptor

A

Pressure receptors in the aorta and vena cava

Detect high or low blood pressure and send nerve impulses along sensory neurons to cardioregulatory centres in the medulla oblongata

39
Q

What is the vagus and accelerator nerve

A

In the medulla oblongata

Accelerator carries impulses from cardioacceleratory centre.

Vagus nerve carries impulses from the cardioinhibitory centre

40
Q

What are prociporeceptors

A

Stretch receptors which detect movement by cardiovascular muscle highlighting a need for oxygen

41
Q

What are chemoreceptors

A

Receptor that responds to a change in chemical composition of fluid around it
Found in arteries aorta and blood

42
Q

What does noradrenaline do

A

Binds to receptors on the SAN to increase heart rate

43
Q

What does cortisol do and where’s it secreted from

A

Stimulates target organs and tissues to increase blood pressure, blood glucose and suppress immune system.

Released by the cortex of the adrenal gland

44
Q

How does aerobic respiration produce ATP

A

Myoglobin will only release 02 in very low po2

ATP generated via oxidative phosphorylation in mitochondria

45
Q

How does anaerobic respiration produce ATP

A

Produces ATP by rapid glycolysis. Produces pyruvate which is converted to lactate by lactate fermentation

46
Q

How does the ATP creatine phosphate system work

A

Creatine phosphate provides a phosphate which binds to ADP to produce ATP
Can only occur for a few seconds- anaerobic and doesn’t produce Laura’s

47
Q

3 ways to generate ATP

A
  1. Aerobic respiration
  2. Anaerobic respiration
  3. ATP-CP system
48
Q

How does action potentials trigger contraction of muscles

A
  1. Trigger depolarisation of sarcolemma
  2. Electrical impulse travel down transverse tubules towards sarcoplasmic reticulum
  3. Sarcoplasmic reticulum triggers release of calcium ions
  4. Calcium ions bind to troponin causing it to change shape. Pulls tropomyosin out of actin-myosin binding site
49
Q

How do calcium ions initiate contraction in skeletal muscle fibres

A

Activates ATPase which breaks down ATP into ADP and P to release energy that moves myosin head

50
Q

What is a sarcomere

A

Unit of a muscle fibre

51
Q

What is the sarcomella

A

Muscle cell membrane

52
Q

What are the structures of a microfibril

A

L band- thin actin
H zone- only myosin
Z- protein discs that hold microfilamentd in place
A band- overlap of actin/myosin darker

53
Q

How does actin-myosin binding happen

A

Tryomyosin held in place by troponin molecules where calcium ions released by the sarcoplasmic reticulum, binds to troponin molecules

Causes troponin to change shape and release tropomyosin to expose the binding site.

Myosin head contains ATP > ADP+ P

Allows to move into extended position ready to spring into action. Binds to actin and changes shape, pulling actin and shortening’s the sacromere. Actin and myosin still bonded- unbinds with ADP so can bind to fresh atp

Changes shape and release actin

54
Q

Difference between NMJ and synapse

A

Only releases acetylcholine

Between motor neurone and skeletal

NMJ always excitatory

55
Q

What causes muscle fatigue

A

Calcium channels become leaky, so muscle can’t can’t fully contract or relax

Lack of atp

Lack of 02

Lactase build uo

56
Q

What causes muscle cramps

A

Build up of lactic acid

ATP depletion

Ion imbalance

57
Q

What is an antagonistic pair

A

Muscles working together, such as biceps and triceps to move bones.

One muscle in pair contracts, and other relaxes

Arm, biceps contracting lifts the lower arm, and triceps contracting lowers it

58
Q

What is a synergist

A

Muscle which aids a prime mover in a movement and helps prevent rotation (surrounds joints)

59
Q

Three types of muscle

A

Skeletal, cardiac, smooth

60
Q

Features of cardiac muscle

A

Myotonic

Intercalated discs which connect fibres

Packed with mitochondria

Contract rhymetically and don’t fatigue

61
Q

What are features

A
62
Q

What are features of skeletal muscle

A

Voluntary, consciously controlled
Fast twitch muscle fibres and slow twitch muscle fibres
Cross striations and many nuclei

63
Q

What are features of smooth muscle

A

Lack cross striations

Found in walls of hollow organs

Spindle shaped

Contract slowly and dont fatigue

64
Q

How do antagonistic pairs work in the elbow

A

Tendons connect muscle to the bone (bicep muscle connected to radius and ulna)

Ligaments hold bones together to prevent dislocation

The synovial membrane secretes synovial fluid to prevent friction

OCR A level bio (10 decks)

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