5.5 - Animal Responses Flashcards
1
Q
State the difference between the central nervous system and peripheral nervous system
A
CNS is the brain and spinal cord
PNS is all other neurones
2
Q
What is the role of the somatic nervous system?
A
- Conscious control of actions
- i.e. voluntary responses
- e.g. throwing a ball, walking
- Carries nerve impulses to skeletal muscles
3
Q
What is the role of the autonomic nervous system?
A
- Subconscious control
- i.e. involuntary reactions
- e.g. pupil dilation, heart beat, food digestion
- Carries nerve impulses to glands, smooth muscle or cardiac muscles
4
Q
Why are autonomic responses necessary?
A
- Frees up conscious areas of brain
- Allows multiple vital tasks to be performed without thinking
5
Q
Why can many autonomic functions also be controlled consciously?
A
- Enables response to certain situations / environments
- e.g. breathing can be controlled
- A person can hold their breath underwater
- Because not possible to breathe normally in this environment
6
Q
Outline the role of the cerebrum
A
Controls voluntary actions
- e.g. learning, memory, conscious thought, walking
7
Q
Outline the role of the cerebellum
A
Controls unconscious functions
- e.g. posture, balance, non-voluntary movement
8
Q
Outline the role of the Medulla oblongata
A
Autonomic control
- e.g. heart rate, breathing rate
9
Q
Outline the role of the hypothalamus
A
Regulatory centre for temperature (thermoregulation) and water balance (osmoregulation)
10
Q
Outline the role of pituitary gland
A
- Anterior pituitary produces hormones
- e.g. FSH
- Posterior pituitary stores and releases hormones produced by hypothalamus
- e.g. ADH
11
Q
Which part of the brain is responsible for the coordination of the autonomic control of heart rate?
A
Medulla oblongata
12
Q
Which part of the brain is responsible for osmoregulation by the kidney?
A
Hypothalamus and pituitary gland
13
Q
Which part of the brain is responsible for the coordination of the muscles involved in walking in an adult?
A
Cerebrum (conscious muscle movement) and cerebellum (balance and coordination)
14
Q
A stroke is when cells in part of the brain die. Explain how the following effects of a stroke are
caused:
- Problems with coordination of movement
- Loss of memory and speech
- Paralysis of the body below the neck
A
Problems with coordination of movement
- Damage to cerebellum
Loss of memory and speech
- Damage to cerebrum
Paralysis of the body below the neck
- Damage to medulla oblongata and/or cerebrum
15
Q
What type of actions are not processed by the brain?
A
Reflex actions
16
Q
Describe the pathway of a reflex arc
A
Receptor → Sensory neurone → Relay neurone → Motor neurone → Effector
17
Q
Describe the actions that take place when you touch a sharp object
A
- Pressure receptors in skin detect change in pressure
- Sensory neurone passes nerve impulses to spinal cord
- Relay neurone passes impulses across the spinal cord
- Motor neurone passes impulses to the effector (a muscle)
- Muscle contracts
- Body part is removed from sharp object
18
Q
What is the purpose of the knee-jerk reflex?
A
Helps body maintain posture and balance
19
Q
What does the absence of a knee-jerk reflex indicate?
A
Nerve damage in spinal cord
20
Q
What type of reflex in the blinking reflex?
A
Cranial reflex
- Occurs in brain
- Involuntary response
21
Q
What is the purpose of the blinking reflex?
A
Prevents objects entering or damaging eye
22
Q
Explain how the blinking reflex occurs
A
- Cornea of eye irritated
- Stimulus triggers impulse along sensory neurone
- Impulses passes along relay neurone in lower brain stem
- Impulses sent along motor neurone to muscles in eyelids
- Causes eyelids to close
23
Q
Explain how a reflex action can improve an organism’s chance of survival
A
Reflex arc does not include the brain
- Involuntary response
- Prevents brain being overloaded
Decreases time taken for body to react to harmful situation
Does not have to be learnt
- Provides immediate protection
24
Q
Define coordinated response
A
- Nervous and endocrine systems working together
- Detect and respond appropriately to stimuli
25
Describe the fight or flight response
- Coordinated response in mammals
- Body reacts to potentially dangerous situations
- Prepares body to either run or fight
26
Which part of the nervous system detects potential threats?
Autonomic nervous system
27
Which part of the nervous system is stimulated in the fight or flight response?
Sympathetic nervous system
28
Which hormones are involved in the fight or flight response?
- Adrenaline
- Noradrenaline
29
Explain the effect of adrenaline on liver cells
- Triggers increase in glycogenolysis
- Makes more glucose available for respiration
30
Where are adrenaline and noradrenaline secreted from?
Adrenal medulla
31
Why can’t adrenaline cross plasma membranes?
Hydrophilic molecule
- Not lipid soluble
32
Describe the function of adenylyl cyclase
- Membrane-bound enzyme
- Found on inside of plasma membrane
- Associated with adrenaline receptor proteins
- Converts ATP to cyclic AMP (cAMP)
33
Describe the function of cAMP
- Acts as second messenger
- Activates other enzymes in the cell
34
How are enzymes activated?
- By phosphorylation
- By changing the tertiary structure
35
Outline the second messenger model of adrenaline action on target cells
- Adrenaline binds to receptor
- Receptor complementary to adrenaline
- Adrenaline acts as first messenger
- Adenylyl cyclase enzyme activated
- ATP converted to cAMP
- cAMP acts as second messenger
- cAMP activates protein kinase enzymes
- Protein kinases activate enzymes to carry out response
36
Suggest how the adrenaline molecule can cause different effects in different target tissues
- Different tissues have different receptors
- Binding of adrenaline to receptors causes cAMP concentration to increase or decrease
- Second messenger may be different in different cells
- cAMP or other second messenger activates different enzymes
37
Explain how the second messenger model enables a small number of adrenaline molecules to
rapidly cause large effects
- One adrenaline molecule causes activation of many other molecules
- Multiplying effect repeated at every step
38
Explain how the nervous system and endocrine system work together to enable the body to
respond to danger
- Danger detected by the autonomic nervous system
- Hypothalamus triggers sympathetic nervous system
- Nervous impulse triggers release of hormones from adrenal medulla
- Adrenaline causes glycogenolysis in liver cells
- Increased blood glucose used for respiration
- Creates ATP for muscle contraction
- Pituitary gland stimulates the adrenal-cortical system
- Hormones release from adrenal cortex
39
Which part of the nervous system is responsible for controlling the heart rate?
Autonomic
40
Which section of the brain is responsible for controlling the heart rate
- Cardiovascular centre
- In medulla oblongata
41
How does the medulla oblongata communicate with the heart?
Sympathetic nervous system
- Impulses transmitted through accelerator nerve
- To sinoatrial node (SAN)
- Increases heart rate
Parasympathetic nervous system
- Impulses transmitted through vagus nerve
- To sinoatrial node (SAN)
- Decreases heart rate
42
What is the role of baroreceptors?
Detect change in blood pressure
43
Where are baroreceptors located?
- Aorta
- Vena cava
- Carotid artery
44
What is the role of chemoreceptors?
- Detect change in chemicals in blood
- e.g. carbon dioxide
- Sensitive to pH level
45
Where are chemoreceptors located?
- Aorta
- Carotid artery
- Medulla oblongata
46
Why does CO2 decrease the pH of blood?
- Carbon dioxide reacts with water
- Forms carbonic acid (H2CO3)
- Carbonic acid dissociates to form hydrogencarbonate ions and hydrogen ions
- H+ ions reduce pH
47
Explain what could cause a decrease in blood pH
- Increase in aerobic respiration
- Produces more carbon dioxide
48
Outline why exercising causes heart rate to increase
Increased metabolic activity
- More CO2 produced by aerobic respiration
- Blood pH lowered
- Detected by chemoreceptors in medulla oblongata and aorta
- Increases frequency of impulses to SAN
- Sent via sympathetic nervous system
- SAN increases heart rate
- Increases rate of depolarisation
- Increased blood flow removes CO2 faster
- CO2 level returns to normal
- Blood pH increases
49
Outline how an increase in blood pressure causes heart rate to decrease
- Baroreceptors in aorta and carotid artery detect increase in blood pressure
- Send impulses to medulla oblongata
- Medulla oblongata sends impulses to SAN
- Sent via parasympathetic nervous system
- SAN decreases heart rate
- Decreases rate of depolarisation
50
Which hormones cause an increase in heart rate?
- Adrenaline
- Noradrenaline
51
Which cells does adrenaline target to increase heart rate?
SAN in heart
52
Outline the hormonal and nervous mechanisms involved in the control of heart rate
- Adrenaline increases heart rate
- Targets cells in SAN
- Cardiovascular centre in medulla oblongata
- Connected by nerves to SAN
- Controls frequency of depolarisation
- Parasympathetic (vagus) nerve decreases heart rate
- Sympathetic (accelerator) nerve increases heart rate
- High blood pressure detected by baroreceptors
- Receptors in aorta, vena cava, carotid arteries
- Low blood pH detected by chemoreceptors
- Receptors in aorta, carotid arteries, medulla oblongata
53
Outline the differences in the ways in which mammalian and plant hormones operate
Mammals - made in endocrine glands
Plants - made in plant tissues
Mammals - move in blood
Plants - move from cell to cell in xylem
Mammals - act on specific tissues
Plants - act on most tissues and in cells where
produced
Mammals - act more rapidly
Plants - act more slowly
54
What is the role of muscles?
- Provide forces that move animals’ bodies
- Only exert force when they contract (not when they relax and lengthen)
- Only cause movement in one direction
55
Online the three types of muscle found in the body
**Skeletal muscle**
- Responsible for movement
**Cardiac muscle**
- Found only in the heart
**Smooth (involuntary) muscle**
- Found in walls of hollow organs
- e.g. stomach, bladder
- Found in walls of blood vessels and digestive tract
56
Describe the structure of skeletal muscle
- Attaches to bone
- Causes movement of animal bodies
- Muscle fibres are multi-nucleated
- Myofibrils consist of sarcomeres (light and dark bands) giving striped appearance
- Contain specialised sarcoplasmic reticulum (store of Ca2+ ions)
57
Which proteins make up the myofibrils?
- Actin
- Myosin
58
What causes the presence of the dark band (A-band)?
Myosin
59
What causes the presence of the light band (I-band)?
Actin only
- No myosin present
60
What is the H zone?
- Region where only myosin is present
- No actin
61
What happens to the size of the sacromere when a muscle contracts?
shortens
62
What happens to the size of the I-band when a muscle contracts?
shortens
63
What happens to the size of the A-band when a muscle contracts?
stays the same
64
What happens to the size of the H-zone when a muscle contracts?
shortens
65
What is the sarcoplasm?
Muscle-fibre cytoplasm
66
What is the sarcolemma?
Plasma membrane surrounding muscle fibre
67
What is the role of the sarcoplasmic reticulum?
Contains calcium ions
68
What are T-tubules?
Inwards folds of sarcolemma
69
What is the role of T-tubules?
- Help spread action potential through sarcoplasm
- Allows depolarisation of sarcoplasmic reticulum
70
What is the role of troponin and tropomyosin?
Block binding sites on actin when muscle is relaxed
71
Explain how an action potential leads to the release of Ca2+ from the sarcoplasmic reticulum
- Action potential arrives at end of motor neurone
- Neurotransmitter (ACh) released causing action potential across sarcolemma
- Action potential spreads along T-tubules
- Action potential causes depolarisation of sarcoplasmic reticulum
- Calcium ions released from sarcoplasmic reticulum
72
Explain the sliding filament model for skeletal muscle contraction
- Calcium ions released from sarcoplasmic reticulum bind to troponin
- Moves tropomyosin so binding sites on actin revealed
- Myosin heads bind to sites on actin to form cross-bridges (1)
- ADP molecule released from myosin head
- Myosin heads move actin filaments in a ‘power stroke’ (2)
- Z-lines pulled towards each other, sarcomeres shortened
- Binding of new ATP causes release of myosin head from actin (3)
- Hydrolysis of ATP to ADP and Pi causes myosin heads to reset (4)
- Cycle repeated
73
What is the role of calcium ions in muscle contraction?
- Calcium ions released from sarcoplasmic reticulum bind to troponin
- Moves tropomyosin so myosin-binding sites on actin are exposed
- Myosin heads can now bind to binding sites on actin
74
Explain why a reduction in Ca2+ availability leads to reduced muscle contraction force
- Fewer Ca2+ ions bind to troponin
- Fewer troponin proteins change shape
- Fewer tropomyosin proteins move aside
- Fewer binding sites on actin available
- Fewer actin-myosin cross bridges form
- Power stroke reduced
- Actin filaments pulled past myosin with less force
75
Explain the role of ATP in the contraction of skeletal muscle
- ATP binds to myosin heads
- ATP binding causes cross bridges between myosin and actin to break
- ATP hydrolysed to ADP + Pi, causing myosin heads to change angle
- Myosin heads attach to binding sites on actin filament further along sarcomere
- ADP + Pi released and myosin heads pull actin filament along (“power stroke”)
76
Outline the function of myosin and actin in muscle contraction
- Myosin binds to actin forming cross-bridges
- Sliding of actin and myosin filaments shortens sarcomere
- ATP used to break cross-bridges
- Myosin heads re-set
- Contraction ceases when myosin head detaches from the actin filament
77
How is ATP supplied to muscle tissue?
- Aerobic respiration
- Anaerobic respiration
- Creatine phosphate
78
Define phosphorylation
Addition of a phosphate group
- e.g. ADP + Pi → ATP
79
Explain how ATP is generated using creatine phosphate
- Creatine phosphate stored in muscle
- Acts as reserve supply of phosphate
- Available to combine with ADP to form ATP
80
What is the advantage of storing creatine phosphate in muscle tissue?
- Generates ATP rapidly
- Used for short burst of vigorous exercise
81
What is the disadvantage of creatine phosphate as an energy source?
- Store of phosphate used up quickly
- Must be replenished using ATP when muscle relaxed
