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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
What is the Z line
Line which marks the end of a sarcomere
26
What can be found in the middle of each sarcomere
M line- middle of myosin filaments Around the M line is the H zone H zone only contains myosin filaments
27
What’s the sliding filament theory
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
What happens to the different bands in sarcomere as it contracts
A band stays same L band gets shorter H zone gets shorter
29
What are some features of myosin filaments
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
What happens to binding sites of resting muscles
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
How does an action potential trigger muscle contraction
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
What happens when the muscle stops being stimulated
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
What is a neuromuscular junction
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
What happens when a chemical blocks the release of a neurotransmitter or blocks the receptor site
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
What is the structure and function of skeletal muscle
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
What’s the structure and function of involuntary muscle
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
How could you monitor muscle fatigue
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
What are baroreceptor
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
What is the vagus and accelerator nerve
In the medulla oblongata Accelerator carries impulses from cardioacceleratory centre. Vagus nerve carries impulses from the cardioinhibitory centre
40
What are prociporeceptors
Stretch receptors which detect movement by cardiovascular muscle highlighting a need for oxygen
41
What are chemoreceptors
Receptor that responds to a change in chemical composition of fluid around it Found in arteries aorta and blood
42
What does noradrenaline do
Binds to receptors on the SAN to increase heart rate
43
What does cortisol do and where’s it secreted from
Stimulates target organs and tissues to increase blood pressure, blood glucose and suppress immune system. Released by the cortex of the adrenal gland
44
How does aerobic respiration produce ATP
Myoglobin will only release 02 in very low po2 ATP generated via oxidative phosphorylation in mitochondria
45
How does anaerobic respiration produce ATP
Produces ATP by rapid glycolysis. Produces pyruvate which is converted to lactate by lactate fermentation
46
How does the ATP creatine phosphate system work
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
3 ways to generate ATP
1. Aerobic respiration 2. Anaerobic respiration 3. ATP-CP system
48
How does action potentials trigger contraction of muscles
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
How do calcium ions initiate contraction in skeletal muscle fibres
Activates ATPase which breaks down ATP into ADP and P to release energy that moves myosin head
50
What is a sarcomere
Unit of a muscle fibre
51
What is the sarcomella
Muscle cell membrane
52
What are the structures of a microfibril
L band- thin actin H zone- only myosin Z- protein discs that hold microfilamentd in place A band- overlap of actin/myosin darker
53
How does actin-myosin binding happen
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
Difference between NMJ and synapse
Only releases acetylcholine Between motor neurone and skeletal NMJ always excitatory
55
What causes muscle fatigue
Calcium channels become leaky, so muscle can’t can’t fully contract or relax Lack of atp Lack of 02 Lactase build uo
56
What causes muscle cramps
Build up of lactic acid ATP depletion Ion imbalance
57
What is an antagonistic pair
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
What is a synergist
Muscle which aids a prime mover in a movement and helps prevent rotation (surrounds joints)
59
Three types of muscle
Skeletal, cardiac, smooth
60
Features of cardiac muscle
Myotonic Intercalated discs which connect fibres Packed with mitochondria Contract rhymetically and don’t fatigue
61
What are features
62
What are features of skeletal muscle
Voluntary, consciously controlled Fast twitch muscle fibres and slow twitch muscle fibres Cross striations and many nuclei
63
What are features of smooth muscle
Lack cross striations Found in walls of hollow organs Spindle shaped Contract slowly and dont fatigue
64
How do antagonistic pairs work in the elbow
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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