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OCR Biology A Level > 5.1.5 Animal Responses > Flashcards

5.1.5 Animal Responses Flashcards

1
Q

Whatr is the CNS protected by?

A
  • Meningines fluid
  • Cerebrospinal fluid
  • Skull + vertebrate bones
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2
Q

Name parts of the brain

A
  • Pituitary gland
  • Frontal Sinus
  • Corpus callosum
  • Cerebrum
  • Thalamus
  • Hypothalamus
  • Cerebellum
  • Pons
  • Medulla oblongata
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3
Q

Name the lobes of the brain

A
  • Frontal lobe
  • Parietal lobe
  • Occipital lobe
  • Temporal lobe
  • Medulla oblongata
  • Cerebellum
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4
Q

Give key detials about the cerebrum

A
  • largest part
  • 2 hemispheres (cojnnected by corpus callosum)
  • outmost layer called cerebral cortex
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5
Q

What do the two hemispheres of the cerebrum control?

A

Right hemisphere: Motor areas control muscle movements of the left side of the body
Left hemisphere: Motor areas control muscle movements of the right side of the body

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6
Q

What is the cerebral cortex responsible for?

A

‘High brain functions’
- Conscious thought + emotional response
- Ability to overide some reflexes
- Intelligence, reasoning, judgement, imagination

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7
Q

What are the 3 areas of the cerebral cortex?

A

Sensory area: Recieves nerve impulses from receptors
Association area: Compares inputs with previous experiences to interpret what the input means and judge appropriate response
Motor area: Send nerve impulses to effectors (muscles + glands)

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8
Q

What are the functions of the cerebral cortex?

A
  • Recieve sensory input
  • Process/coordination of information
  • Transmits impulses to effectors
  • Control of voluntary action
  • Thought/memory
  • Speech + personality/emotion
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9
Q

What does the size of the motor area affect?

A

Complexity of the movements

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10
Q

What does the sub-conscious part of the cerebellum do?

A
  • Fine tunes muscles for posture to remain upright/balanced
  • Fine tunes tensioning + feedback for fine coordination to use tools
  • Sensory activites for judging positioning
  • Operation of anatagonistic muscles
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11
Q

How does the cerebellum help control muscles?

A

Neurones transmit impulses from cerebellum to motor areeas of cerebrum to adjust output to effectors
Seems like autopilot
Iput to cerebellum from retina, spindle fibres in muscles, joints

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12
Q

What are the roles of the hypothalamus?

A

Controls homeostatic mechanisms
Controls most of the hormonal endocrine system as regualtes the pituitary gland
Recieves inputs from thermo +osmo receptors
Controls autonomic nervous system

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13
Q

Explain the role of the hypothalamus in thermoregulation

A

In thermoregulatory centre:
Heat gain centre - activated by fall in blood temp
Heat loss centre - activated by rise in blood temp
Recieves input from thermoreceptors in hypothalamus
+ peripheral thermoreceptors in skin - monitor external temp

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14
Q

Explain the role of the hypothalamus in thermoregulation

A

Blood flows through hypothalamus - water potential monitored
Produces ADH - stored in pituitary gland
Released into blood when water potential drops

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15
Q

What does the pituitary gland regulate?

A
  • Hunger + thirst
  • Body temp
  • Production of reproductive hormones (LH, FSH)
  • Production of ADH for osmoregulation
  • Prodution of ACTH for fight/flight response
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16
Q

What is the role of the medulla oblongata?

A

Controls all involuntary muscles (Autonomic nervous system)
- breathing (respiratory centre)
- heart rate (cardiovascular centre)
- circulation
- swallowing, salvation, vomiting reflex

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17
Q

Give an overview of the CNS

A

Central Nervous System
- Brain + spinal cord
- Includes intermediate/relay neurones
- Has a coordination role

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18
Q

Give an overview of the PNS

A

Peripheral Nervous System
- Sensory + motor neurones that transmit impulses to + from the CNS
- Involves nerves from sense organs + nerves to muscles/glands
- Role in sensing stimuli + controlling effectors
- Includes somatic, autonomic, sympathetic + parasympathetic nervous systems

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19
Q

Explain the structure of the PNS

A

Sensory System: Receptors + sensory neurones transmit impulses to CNS
Somantic Nervous system: Conscious myelinated motor neurones transmit impulses to voluntary muscles(Effectors) Conscious
Autonomic Nervous System (Unconscious)
- Sympathetic Division: Unmyelinated motor neurones to smooth muscle/glands (Uses Noradrenaline) Fight or flight
- Parasympathetic Division: Unmyelinated motor nrurones to smooth muscle/glands (Uses Acetylcholine) Rest or digest

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20
Q

Compare the autonomic + somantic systems

A

Mylinated
Autonomic: Unmyelinated or lightly myelinated
Somatic: Always myelinated
Motor Neurones
Autonomic: At least 2 motor neurones connected to effector (Connected by ganglion)
Somatic: Only 1 motor neurone to the effector
Types of neurone
Autonomic: Sympathetic or parasympathetic
Somatic: Just motor neurones

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21
Q

Compare the sympathetic + parasympathetic systems

A

Active When…
Sympathetic: Times of stress
Parasympathetic: Rest + relaxation
Pre-ganglionic Length
Sympathetic: Pre-ganglionic neurones short
Parasympathetic: Can vay considerably in length
Effects Of Action
Sympathetic: Increased heart + ventilation rate, pupil dilation,
Parasympathetic: Decreased heart + ventilation rate, pupil constriction
Neurotransmitters
Sympathetic: Noradrenaline - at effector
Parasympathetic Acetylcholine - at ganglion

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22
Q

Name 3 types of muscle

A
  • Skeletal (voluntary/striated)
  • Cardiac muscle
  • Smooth muscle (involuntary)
23
Q

Compare the 3 types of muscle

A

Striation
Skeletal: Striated
Smooth: Unstriated
Cardiac: Semi-striated
Cell Type + Nucleus
Skeletal: Cylindical + multinucleate
Smooth: Spindle-shaped cells with single nucleus
Cardiac: Cylindrical with single nucleus, branch + connect to other cells
Location Found
Skeletal: Attached to bone
Smooth: Walls of tubular structures - gut, vessels, ducts
Cardiac: Only in heart
Controlled By
Skeletal: Somatic nervous system
Smooth: Autonomic nervous system
Cardiac: Autonomic nervous system
Contraction + Tiredness
Skeletal: Contracts quickly but tires easily
Involuntary: Contracts slowly but tires slowly
Cardiac: Contracts spontaneously without fatigue

24
Q

Give key details about cardiac muscle

A

Pumps blood around the body
Myogenic (Contracts spontaneously)
3 Types: Atrial, entricular, excitatory + conductige muscle fibres (SAN, AVN, Bundle of his, Purkyne fibres)
Atrial + ventricular contract for longer than skeletal

25
Q

What is the purpose of intercalated discs in cardiac muscle membranes?

A

Gaps that allow free ion diffusion for quick + easy action potential transmission

26
Q

How is cardaic muscle controlled by different nervous systems?

A

Myogenic - can contract without impulse from the brain
Nerve impulses from brain regulate rate of muscle contraction by regulating frequency of SAN giving out wave of excitation
Sympathetic NS causes increased rate of muscle contraction by increasing rate of SAN giving out wave of excitation
Parasympathetic NS causes decreased rate of muscle contraction by decreasing rate of SAN giving out wave of excitation

27
Q

Where is involuntary (smooth) muscle found?

A

Walls of tubular structures e.g.
- bronchi/bronchioles
- arteries/arterioles
- oesophagus

28
Q

Explain the structure of skeletal muscles

A
  • Many nuclei
  • Sarcolemma membrane
  • Sarcoplasm (cytoplasm)
  • Many mitchondria to create ATP for contraction
  • Sarcoplasmic reticulum contains calcium ions
  • Many myofibrrils made from thin actin protein + thick myosin
29
Q

What type of muscle are intercostal + diaphragm muscles?

A

Skeletal as they are connected to the skeleton

30
Q

Explain the process of an action potential moving accross a neuromuscular junction

A
  1. Action potential causes calcium ions channels in pre-synaptic membrane to open - calcium ions enter pre-synaptic knob
  2. Acetylcholine vesicles fuse with presynaptic membrane - acetylcholine released by exocytosis from vesicle
  3. Acetylcholine diffuses across cleft + binds to receptors associated with Sodium ion channels in post-synaptic membrane (sarcolemma)
  4. Sodium ion channels open in Sarcolemma + sodium moves into muscle fibre - T tubule system is depolarised
  5. T tubule system depolarisation causes Calcium ions stored in sarcoplasmic reticulum to be released
  6. Calcium ions bind to muscle proteins caled Troponin - causes muscle contraction
  7. Acetylcholinesterase breaks down acetylcholine to reverse process
31
Q

Why are so many mitochondria needed in the neuromuscular junction?

A

Mitochondria produce ATP
- Sodium/potassium pump uses ATP to restore + maintain resting potential after depolarisation
- ATP needed for neurotransmitter formation
- ATP needed for vesicle formation
- ATP needed for vesicle movement (motor proteins on microtubule)
- ATP needed for exocytosis - fusing with cell surface membrane of pre-synaptic neurone
- ATP needed for active transport of acetylcholine into vesicles + calcium transported out of pre-synaptic neurone
- ATP needed for endocytosis of neurotransmitter into pre-synaptic neurone
- ATP needed for active transport of calcium into sarcoplasmic reticulum
- ATP needed for synthesis of proteins
- ATP neded for sliding filament hypothesis

32
Q

Compare a synapse between two neurones + a neuromuscular junction

A

Neurone to…
2 neurones: Neurone to neurone
Neuromuscular junction: Neurone to muscle cell
Postsynaptoc stimulation leads to…
2 neurones: Action potential in post synaptic neurone
Neuromuscular junction: Depolarisation of sarcolemma + muscle contraction
Ends at…
2 neurones: Post-synaptic knob w/ round smooth surface
Neuromuscular junction: Motor end plate w/ undulating surface
T tubules?
2 neurones: No
Neuromuscular junction: Yes
Neurotransmitter
2 neurones: Acetylcholine
Neuromuscular junction: Acetylcholine or nor-adrenaline
Type of depolarisation
2 neurones: Always excitatory
Neuromuscular junction: Can be inhibitory or excitatory

33
Q

List similarities between a synapse between 2 neurones and at a neuromuscualr junction

A

Both:
- have neurotransmitters in vesicles in presynaptic knob
- vesicles fuse ith presynaptic membrane
- involve exocytosis
- neurotrasmitter diffuses accross synaptic clkeft
- neurotransmitter bidns to receptors on sodium ion channels
- neurotransmitter binding causes sodium ion channels to open
- involve neurotransmitter binding to receptor causing depolarisation
- involve enzymes that hydrolyse the neurotransmitter

34
Q

How are different degrees of muscle contraction achieved?

A

Branched neurones at the muscular junctions attach to a cluster of muscle cells (a motor unit)
The more motor units stimulated the greater the force of contraction

35
Q

Explain the structure of skeletal muscle

A

Muscle consists of bundles of long cells called muscle fibres
Muscle fibres contains numerous myofibrils
Myofibrils are made from repeating units of sacromeres
Sacromerees are made from overlapping thick myosin and thin actin filaments

36
Q

Describe the structure of a sacromere

A

(From outwards in)
- Z lines seperate sacromeres
- I band contains only actin
- A band contains both action + myosin
- H zone contains only myosin
- M line is middle of the sacromere

Myofibrils arranged in hexagonal organisation of actin and myosin filaments in cross section

37
Q

How does the structure of the sacromere change when contracted?

A
  • Thick + thin filaments do not change length
  • A band remains constant
  • I band decreases
  • H zone decreaes
  • Z lines move closer together
38
Q

Explain the structure of actin

A
  • Surrounded by tropomyosin (prevents myosin head binding to actin)
  • Contains a troponin (Calcium ion receptor)
39
Q

Explain the sliding filament hypothesis

A
  1. ATP detaches myosin head from actin-myosin binding site on actin
  2. Hydrolysis of ATP to ADP+Pi gives energy to move myosin head backwards (resets myosin head)
  3. Sarcoplasmic reticulum releases calcium as action potential reaches neuromuscualr junction
  4. Calcium binds to troponin
  5. Troponin changes shape, so tropomyosin moves, exposing actin-myosin binding site
  6. Myosin head attaches to actin-myosin binding site forming cross bridges
  7. ADP + Pi molecule released and myosin head moves, causing actin filaments to slide past stationary myosin filaments
  8. Actin filament moved past stationary myosin filament (power stroke)
40
Q

Why is ATP important for muscle contraction?

A
  • Needed to break thge cross nridge between actin + myosin
  • Needed to provide energy to reset the myosin head so it can bind to actin
  • Needed to actively transport calcium ions from the sarcoplasm back into the sarcoplasmic reticulum
41
Q

How is creatine phosphate used in muscle contraction?

A

Muscles can store creatine phosphate, which can donate a phosphate to restore ATP (requires phosphocreatinase enzyme)

42
Q

How does the medulla oblongata control heart rate?

A

Contains the cardiovascular centre
- Acceleratory centre increases heart rate (sympathetic accelerator nerve)
- Inhibitory centre decreases heart rate (parasympathetic vagus nerve)
Each centre connected to the SAN with motor neurones of autonomic nervous system
Affect the frequency the SAN releases a wave of excitation, therefore affecting the frequency of cardiac muscle contraction

43
Q

Explain the stages the cardiovascular centre takes to increase heart rate

A
  1. Acceleratory centre stimulated
  2. Nerve impulse conducted down sympathetic accelerator nerve to SAN
  3. Via short preganglionic neurone
  4. Pre-synaptic knob secretes noradrenaline
  5. SAN increases frequency of waves of excitation
  6. Heart rate increases
44
Q

Explain the stages the cardiovascular centre takes to decrease heart rate

A
  1. Inhibitory centre stimulated
  2. Nerve impulse conducted down parasympathetic vagus nerve to SAN
  3. Via long preganglionic neurone
  4. Pre-synaptic knob secretes acetylcholine
  5. SAN decreases frequency of waves of excitation
  6. Heart rate decreases
45
Q

How would excersise or high blood pressure cause heart rate to change?

A

During Excersise
1. CO2 levels increase, lowering blood pH
2. Chemoreceptors detect change
3. Conduct nerve impulses to CVC in Medulla Oblungata
4. Acceleratory centre activated

High Blood Pressure
1. Blood pressure higher than normal
2. Baroreceptors (Stretch) detect change in aorta
3. Conduct nerve impulses to CVC in Medulla Oblungata

46
Q

Define the fight or flight response

A

A physiological reaction that occurs in response ti a perceived harmful event, attack or threat to survival
- Range of coordinated responses of animals to danger
- Involves autonomic - sympathetic nervous system + endocrine system

47
Q

List physiological changes during fight or flight response

A
  • Dilated pupils
  • Heart rate increase
  • Arteriole to digestion constricts
  • Arteriole to muscles + liver dilates
  • Blood glucose levels increase
  • Metabolic rate increases
  • Erector pili muscles contract (hair stands)
  • Ventilation rate increases
  • Endorphins released in brain
  • Sweat production increases
48
Q

What other responses to animals have to stressors?

A
  • Play dead
  • Camouflage into the background
49
Q

Explain the fight or flight’s nervous response

A
  • Visual/auditory threat is stimulus
  • Nerve impulse conducted along sensory neurones to cerebral cortex
  • Cerebral cortex conducts nerve impulses to hypothalamus to activate it
  • Stimulates activity of the sympathetic nervous system + decreases activity of parasympathetic nervous system
  • Adrenaline released by stimulation of sympathetic nervous system
  • Hormones CRF + ACTH secreted by hypothalamus
50
Q

What glands are used in the fight or flight response?

A

Adrenal Medulla
- Releases adrenaline (amino acid derivative - hydrophilic)
- Binds to plasma membrane receptors
- Causes effects

Adrenal Medulla
- Releases NORadrenaline (amino acid derivative)
- Works with Adrenaline to respond to stress
- Causes effects

Adrenal Cortex
- Produces steriod hormones after activation by hormones from the pituitary gland
- Produces Mineralocorticoids, Glucorticoids + Androgens

51
Q

Explain the effects of Mineralocorticoids, Glucorticoids + Androgens

A

Mineralocorticoids
- Include aldosterone
- Enter cells causing control of concentration of ions in blood
- Helps control blood pressure
- Release mediated by kidney

Glucorticoids
- Includes cortisol
- Controls metabolism of proteins + carbohydrates in the liver
- Helps regulate blood pressure + cardiovascular function when stressed

Androgens
- Works with cortisol to regulate immune response + supress inflammatory reactions

52
Q

What is the difference between a first and second messenger?

A

First messenger: The hormone that transmits a signal around the body e.g. adrenaline
Second messenger: The chemical that transmits the signal inside the cell e.g. cAMP

53
Q

Explain the secondary messenger model using Adrenaline

A
  1. Adrenaline (1st messenger) binds to specific receptors on different target cells - receptor changes shape
  2. An enzxyme is activated, converting many ATP into cAMP
  3. cAMP activates many other enzymes, stimulating hydrolysius of glycogen

OCR Biology A Level (24 decks)

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