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OCR A Level Biology > Module 5: Animal responses > Flashcards

Module 5: Animal responses Flashcards

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1
Q

How is the nervous system organsised

A

Split into central and peripheral nervous system
Central: Brain and spinal cord
Peripheral: somatic and autonomic
autonomic: parasympathetic and sympathetic

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2
Q

What does the somatic nervous system do

A
  • conscious control (running etc)

- skeletal muscles

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3
Q

What does the autonmic nervous system do

A

controls unconscious activities

like heart rate, breathing, digestion

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4
Q

What does the parasymapthetic nervous system do

A

rest and digest

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5
Q

What does the symapthetic nervous system do

A

Fight or flight

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6
Q

What are the different parts of the brain

A 
Cerebrum
Hypothalamus
Medulla oblongata
Cerebellum 
Pituraity gland
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7
Q

What function does the cerebrum have

A

controls:
voluntary actions
personality
learning, hearing and thinking

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8
Q

What function does the cerebellum do

A

Coordinates muscle movement

particularly balance and posture

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9
Q

What function does the medulla obolongata have

A

autonomic control

Controls heart rate, breathing rate

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10
Q

What function does the hypothalamaus have

A

Automatically maintains body temperature
monitors blood glucose level, water levels
Sympathetic nervous system
produces hormones that control the pituitary gland

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11
Q

What function does the pituitary gland have

A

Split into anterior (produces hormones like FSH) and posterior glands (stores hormones made by hypothalamus like ADH)
Releases hormones to stimulate other glands

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12
Q

What is a reflex action

A

an action where the body respsonds to stimulas without making a concious decison

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13
Q

Explain how the blinking reflex works

A

Stimulas: something touches the eye
Receptors: an impulse is sent along sensory neurone to CNS
CNS: passed from relay neurone to motor neurone
Effector: motor neuones send impulses to muslces that move your eyelid
Response: msucles contract (obicularis oculi) causing eyelids to cloe quickly (prevents damage)

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14
Q

Explain the knee jerk reflex

A

Stimulas: detects quadracepst has been streched
Receptors: strech receptors in quadriceps muscles detect that muscle is being streched, then impusle passed along sensory neurone
CNS: sensory neurone communicates with motor neurone in spinal cord
Effectors: motor neurone carries impulse to quadriceps
Response: quadriceps muscle contarcts so lower legs move forwards

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15
Q

Describe the flight or fight response (ACTH)

A

Hypothalamus also releases a peptide hormone that stimulates the anterior pituitary gland to release ACTH
ATCH is transported to the adrenal glands through the bloodstream
Causes adrenal cortex to secrete the hormone cortisol
Cortisol stimulates target organs and tissues to increase blood pressure, blood glucose ensuring the tissues have sufficient glucose and oxygen needed for rapid response
Cortisol also suppresses the immune system

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16
Q

Describe fight or flight response (adrenaline)

A
  • Heart rate increases
  • Muscles around bronchioles relax, causing airways to widen
  • intercoastal muslces and diaphragm contract faster
  • Glycogen is converted to glucose
  • erector pilli muscles contract
17
Q

What part of the nervous system triggers the fight or flight response

A

hypothalamus activates hormonal system and sympathetic nervous system

18
Q

What is the receptor called that detects high or low blood pressure

A

Barorecpetor

19
Q

What is the receptor called that detects changes in co2 concentration and pH

A

Chemoreceptors

20
Q

Describe how heart rate is controlled when there is a high blood pressure

A
  • barcoreceptors in aorta and cartoriod atery detect high bp
  • impulse sent via sesnory neruone to cardiovascular centre
  • impulse sent along parasympathetic neurone
  • these secrete acetycholine which binds to recpetors on SAN (sinoatrial node)
  • heart rate slows, bp back to normal
21
Q

Describe how heart rate is controlled when there is a low blood pressure

A
  • baroreceptors in the aorta and cartoriod artery detect low bp
  • impulse sent via sesnory neruone to cardiovascular centre
  • impulse sent along sympathetic neurone
  • these secrete noradrenaline which binds to recpetors on SAN (sinoatrial node)
  • heart rate speeds up, bp back to normal
22
Q

Describe what happens when there is a high blood pH levels or low co2, and high o2

A
  • chemoreceptors in aorta, carotid arteries and medulla oblongta detect chemical change
  • impulse sent along sensory neurone to the cardiovascular centre
  • impulse sent along parasympathetic nerve
  • acetylcholine is secreted which binds to SAN (sino atrial node)
  • causes heart rate to decrease
  • so oxygen, carbon dioxide and pH levels back to normal
23
Q

Describe what happens when there is a low blood pH levels or high co2, and low o2

A
  • chemoreceptors in aorta, carotid arteries and medulla oblongta detect pH change
  • impulse sent along sensory neurone to the cardiovascular centre
  • impulse sent along sympathetic nerve
  • noradrenaline is secreted which binds to SAN (sinoatrial node)
  • causes heart rate to increase
  • so oxygen, carbon dioxide and pH levels back to normal
24
Q

What other hormone can bind onto receptors to cause the cardiac muscle to contract more frequently

A

Adrenaline

25
Q

Describe the structure of the skeletal muscle

A
  • made of long fibres called muscle fibres
  • around the fibres is a cell membrane called sarcolemma
  • bits of sarcolemma fold inwards into the sarcoplasm
  • these folds are called transverse tubules
  • the sarcoplasmic reticulm runs through the sarcoplasm
  • they are made up of myofibrils (cylindrical organelles
26
Q

What is the role of transverse tubules

A

help spread electrical impulses throughout the sarcoplasm

27
Q

What is the role of the sarcoplasmic reticulum

A

stores and releases calcium ions needed for muscle contraction

28
Q

Describe the structure of myofibrils

A

contains bundles of thick and thin myofilaments which slide past each other during contraction
thick myofilaments: myosin
thin myofilaments: actin

29
Q

Describe the structure of myosin filaments

A
  • fibrous protein molecules with a globular head

- heads are hinged so they can move back and forth

30
Q

Describe the structure of actin filaments

A

Two actin chains twist together to form one thin filament
A fibrous protein known as tropomyosin is twisted around the actin chain
the chain also has troponin as well
have binding site known as actin-myosin site

31
Q

Why can’t myosin bind to actin when the muscle is at rest

A

the binding site is blocked by tropomyosin

32
Q

How does a muscle contract

A
  1. An action potential arrives at the neuromuscular junction
    2 .this depolarises the sarcolemma, which spreads down to the T tubules
  2. This causes calcium ions are released from the sarcoplasmic reticulum (SR)
  3. Calcium binds onto troponin causing a change in shape
  4. Myosin binding sites are exposed on the actin molecules
  5. A actin-myosin cross bridge is made when the mysoin head binds with the actin filament
  6. Calcium ions activate ATPase (breaks down ATP to ADP and phosphate ion)
  7. energy realised causes myosin head to move side to side, it also provides energy for myosin to release actin filaments
    9.myosin heads move back to their original positions and bind to new binding sites on the actin filaments, closer to the Z disc
  8. The myosin heads move again, pulling the actin filaments closer the centre of the sarcomere, causing the sarcomere to shorten once more and pulling the Z discs closer together
    12.myosin heads hydrolyse ATP once more in order to detach again
33
Q

How does the muscle relax

A
  1. Calcium ions leave the binding site on troponin and move back into the sarcoplasmic reticulum via active transport
  2. this means tropomyosin molecules can block the binding site
  3. actin filaments move back to a relaxed position
  4. Sacromere is longer
34
Q

What are the three ways to produce energy for muscle contraction

A
  1. aerobic respiration
  2. Anaerobic respiration
  3. ATP-creatinine phosphate system
35
Q

What are the three types of muscle?

make sure you can describe their structure

A

Cardiac (heart)
Smooth (involuntary)
skeletal (voluntary)

36
Q

What neurotransmitter is released at the neuro muscular junction

A

Acetylcholine

37
Q

What is the receptor at the neuromuscular junction called

A

nicotinic cholinergic receptors

38
Q

How can drugs affect neuromuscular junctions

A

may block the release of acetylcholine
this means it won’t bind onto the nicotinic cholinergic receptor
action potential can’t be passed onto muscle
which means muscle cell cannot depolarise

this can be fatal if the muscle helps with ventilation like intercoastal muscles or the diaphragm
But it is used in surgeries sometimes an example being pancurioiumn bromide which competes with ACh stopping the depolarisation of the muscle

OCR A Level Biology (24 decks)

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