Animal responses Flashcards
blurt: label brain diagram (106 cards)
1
Q
reflex actions
A
involuntary/innate responses to certain stimuli which are very fast and serve a protective purpose from tissue damage
1
Q
six examples of reflex actions
A
- yawning
- saliva production
- swallowing
- constriction of irises/pupillary reflex
- withdrawal reflex (moving in response to pain)
- blinking (unless done voluntarily)
2
Q
two parts of the nervous system
A
CNS (central nervous system) - brain and spinal chord
PNS (peripheral nervous system) - all nerves in body
3
Q
nerves vs neurones
A
nerves are bundles of neurones (nerve cells)
4
Q
functional organisation of the nervous system
A
somatic - voluntary control
autonomic - involuntary/subconscious control
5
Q
three examples of the autonomic nervous system
A
- heart rate
- vasoconstruction /dilation
- gut contraction (peristalsis)
6
Q
two parts of the autonomic nervous system
A
sympathetic - controls fight or flight response
parasympathetic - control the rest and digest system
7
Q
what hormone does the sympathetic nervous system control?
A
adrenaline
8
Q
five parts of the brain
A
- cerebrum
- cerebellum
- medulla oblongata
- hypothalamus
- pituitary gland
9
Q
five cerebrum functions
A
- vision
- hearing
- speech
- memory
- thinking
(generally senses and thoughts)
10
Q
structure of the cerebrum
A
- divided into five lobes
- divided into two halves (cerebral hemispheres)
- hemispheres joined together by corpus callosum (band of nerve fibres)
- cerebral cortex/grey matter (thin outer layer)
- white matter (thin layer beneath grey matter)
11
Q
which side of the body does the right hemisphere control?
A
left side
12
Q
adaptation of the cerebral cortex/grey matter
A
- highly folded (increase SA) to contain a greater number of neurones (therefore more connections between neurones) to carry out complex behaviours
13
Q
what does the cerebral cortex/grey matter contain?
A
cell bodies of neurones
14
Q
what does the white matter consist of?
A
myelinated axons of neurones
15
Q
how does the hypothalamus contribute to homeostasis
A
monitor blood as it flows through (and secretes hormones OR stimulates pituitary gland to secrete hormones)
16
Q
what does the hypothalamus regulate?
A
- water content (osmoregulation)
- digestive activity (controls feeling of hunger, secretion of gut enzymes and peristalsis)
- internal body temperature
- endocrine functions (stimulates pituitary gland)
17
Q
function of the pituitary gland
A
secrete a range of hormones that directly stimulate target cells OR stimulate other glands
18
Q
two parts of the pituitary gland (and their functions)q
A
- anterior pituitary (produces and secretes certain hormones)
- posterior pituitary (stores and secretes hormones produced by the hypothalamus)
19
Q
two hormones that the hypothalamus produces
A
- ADH
- oxytocin
20
Q
function of the cerbellum
A
control motor coordination (such as balance)
21
Q
what parts does the cerebellum coordinate (for balance)?
A
- semicircular canals (ears)
- eyes
- muscles
22
Q
is the cerebellum somatic or autonomic?
A
autonomic (only functions subconsciously)
23
Q
function of the medulla oblongata
A
controls involuntary movement
24
three things that the medulla oblongata controls
- cardiac centre (heart rate)
- vasomotor centre (blood pressure by controlling contraction of smooth muscle in arterioles)
- respiratory centre (breathing rate )
25
two parts of the respiratory centre
- inspiratory centre
- expiratory centre
26
why do erector muscles contract in response to adrenaline?
makes the animal look larger and more aggressive
27
given that cortisol causes an increase in blood pressure, increase in blood sugar levels and suppression of the immune system, suggest the long term adverse effects of continued exposure to stress on body function. (2 marks)
- increased blood pressure could lead to cardiovascular problems
- increased blood glucose concentration could lead to diabetes
- suppression of immune system can lead to increased susceptibility to disease
28
sequence of components in a reflex action
- stimulus
- receptor
- coordinator
- effector
- response
29
what is the coordinator in most reflexes? and what is another coordinator in some reflexes?
- spinal chord (main)
- unconscious parts of the brain (less common)
30
steps involved in a withdrawal reflex (e.g. from heat)
- heat (stimulus) detected by thermoreceptors in skin
- action potential initiated in a sensory neurone
- sensory neurone conduction of impulse to spinal cord
- relay neurone conducts impulses across the spinal cord
- motor neurone conducts impulses to the muscle
- muscle contracts and handers withdrawn from the heat
31
32
knee jerk reflex sequence
- leg tapped just below patella
- patella tendon stretches (stimulus)
- mechanoreceptors stimulated in quads
- action potential initiated in a sensory neurone
- nerve impulse crosses a single synapse straight to a motor neurone
- nerve impulses conducted by a motor neurone to the quad muscle
- quad muscle contracts, flexor muscle relaxes (relay neurones inhibit the contraction of flexor muscles)
- leg straightens
33
spinal reflex
the neural circuit only goes up to the spinal cord, not the brain
34
which parts of neurones are in the spinal cord?
- whole of relay neurones
- end of sensory neurones
- start of motor neurones
35
purpose of the knee jerk reflex
- maintain posture and balance
- e.g. when deers fall to the ground, the knee jerk reflex is stimulated causing them to automatically get back up to escape from predators
36
what is the stimulus, receptor, coordinator and effector in the knee jerk reflex?
stimulus - stretching of the quad
receptor - mechanoreceptors in quad
coordinator - spinal cord
effector - quadricep muscle
37
why is the knee jerk reflex so fast and automatic?
- impulse isn't conducted all the way to the brain (faster and brain doesn't make a decision on it)
- impulse only crosses a single synapse (only one singular sensory and one singular motor neurone involved)
38
where is the impulse conducted to in the knee jerk reflex?
- quadricep muscle (effector)
- brain - which will still allow information about the stimulus but by the time the brain receives and processes the information, the response will have already occurred
39
what is the importance of reflexes?
- involuntary responses prevents the brain from being overloaded with situations in which the response is always the same
- innate so provide immediate protection
- extremely fast (reflex arc very short)
- everyday actions such as digestion, breathing and balance etc
40
three types of muscle
- skeletal muscle
- cardiac muscle
- involuntary muscle (smooth muscle)
41
fibre appearance of the three types of muscle
skeletal - striated
cardiac - specialised striated
involuntary - non-striated
42
contraction speeds of the three types of muscles
skeletal - rapid
cardiac – intermediate
involuntary - slow
43
length of contraction of the three types of muscle
skeletal - short
cardiac - intermediate
involuntary - can remain contracted for a relatively long time
44
skeletal muscle structure (brief)
- striated muscles
- fibres are tubular and multinucleated
45
cardiac muscle structure
- fainter striations
- fibres are branched and uninucleated
46
involuntary muscle structure
- no cross striations
- fibres are spindle-shaped and uninucleated
47
detailed structure of skeletal muscle
- muscles made up of bundles of muscle fibres
- muscle fibres made up of myofibrils
- sarcolemma (plasma membrane enclosing myofibrils within fibre)
- sarcoplasm (shared cytoplasm within a muscle fibre)
- transverse/T tubules (sarcolemma folds inwards to spread electrical impulses through the sarcoplasm)
- sarcoplasmic reticulum
- multiple nuclei
- many mitochondria
48
what does the sarcoplasmic reticulum contain and why is it important?
- contains Ca2+ (stimulate contraction)
- synthesise lots of proteins such as actin and myosin etc
49
why do muscle fibres have lots of mitochondria?
lots of ATP required for muscle contraction (sliding filament theory)
50
adaptations of skeletal muscle cells (fibres)
- many mitochondria
- multiple nuclei
- longer than normal cells
51
why are muscle fibres longer than normal cells?
- formed as a result of many individual embryonic muscle cells fusing together
- makes muscle stronger as the junction between adjacent cells would act as a point of weakness
52
two types of protein filament in myofibrils
- actin
- myosin
53
structure of actin
- thinner than myosin
- two strands twisted around each other
- actin-myosin binding sites
54
structure of myosin
- thicker than actin
- long rod-shaped fibres (made up of myosin tails) with bulbous heads that project to one sided
55
I bands
- light bands
- areas that appear light as they are the region where the actin and myosin filaments DO NOT OVERLAP (only actin)
56
A bands
- dark bands
- appear dark because of the presence of thick myosin filaments
- edges are particularly dark as the myosin overlaps with actin
(includes WHOLE of myosin + overlap)
57
Z line
- found at the centre of each light band
- centre/connects actin filaments
58
sarcomere
distance between two Z lines (functional unit of the myofibril)
59
H zone
- lighter coloured region
- found in the centre of each dark band
- only myosin filaments present
60
arrangement of the three types of muscle
skeletal - regularly arranged so muscle contracts in one direction
cardiac - cells branch and interconnect resulting in simultaneous contraction
involuntary - no regular arrangement so different cells can contract in different directions
61
structure of myosin heads
- globular heads
- hinged to allow them to move back and forth
- binding site for actin and ATP
62
proteins in a sarcomere
- actin
- myosin
- tropomyosin
- troponin
63
tropomyosin
protein twisted around actin blocking the actin-myosin binding sites whilst the muscle is relaxed
64
troponin
globular protein attached to tropomyosin at regular intervals to hold tropomyosin in place
65
what triggers the actin-myosin heads to be exposed?
- action potential arrives at neuromuscular junction
- Ca2+ released from sarcoplasmic reticulum and diffuse into sarcoplasm
- Ca2+ bind to troponin causing a conformational change
- causes tropomyosin to change position on the actin filaments
- myosin binding sites are exposed
66
what is formed when myosin heads bind to actin-myosin binding sites?
cross-bridges
67
power stroke
movement of the myosin heads
68
neuromuscular junction
- works similarly to a synapse
- located between the neurone and a muscle cell
69
transmission across a neuromuscular junction steps
- action potential depolarises presynaptic membrane
- voltage-gated Ca2+ channels open
- Ca2+ diffuse into presynaptic knob down an electrochemical gradient
- Ca2+ stimulate synaptic vesicles to fuse with presynaptic membrane and release acetylcholine via exocytosis
- acetylcholine diffuses across synapse
- binds to cholinergic receptors on postsynaptic membrane (sarcolemma)
- voltage-gated Na+ channels open
- sarcolemma is depolarised
- acetylcholine broken down by acetylcholineesterase
- choline and ethanoic acid diffuse back into motor neurone where they recombine into acetylcholine using energy provided by mitochondria
70
what does acetylcholine break down into?
- choline
- ethanoic acid
71
what enzyme breaks down acetylcholine?
acetylcholinesterase
72
why most acetylcholine be broken down?
- close voltage-gated Na+ channels in the postsynaptic membrane
- create distinct impulses
73
how does depolarisation of the sarcolemma expose the actin-myosin binding sites?
- depolarisation travels into the muscle fibre through T-tubules
- action potential stimulates voltage-gated Ca2+ channels to open
- Ca2+ diffuse down an electrochemical gradient into the sarcoplasm
- Ca2+ bind to troponin causing a conformational change
- this change causes a conformational change in tropomyosin exposing the actin-myosin binding sites
74
four differences between cholinergic synapses and neuromuscular junctions
- synapses found between neurones
- neuromuscular junctions found between a motor neurone and a muscle cell
- in cholinergic synapses, postsynaptic membrane depolarises
- in neuromuscular junctions, the sarcolemma depolarises
- cholinergic synapses can be excitatory or inhibitory
- neuromuscular junctions can only be excitatory
- summation can occur in cholinergic synapses
- summation cannot occur in neuromuscular junctions
75
three similarities between cholinergic synapses and neuromuscular junctions
- both use only acetylcholine
- both stimulated by an action potential from a presynaptic membrane
- both can be excitatory
76
what happens once the myosin head bonds to the actin-myosin binding site?
- myosin head forms a cross-bridge
- ADP + Pi released
- myosin head to change shape and pulls actin towards centre of the sarcoma (power stroke)
- ATP binds to myosin head
- cross-bridge breaks
- ATP hydrolysed releasing energy
- myosin head moves back to original position (leaning forwards)
- myosin head is free to bind to the next actin-myosin binding site
- process continues as long as Ca2+ are present
77
motor unit
all muscle fibres supplied by a single motor neurone act as a single unit
78
how do motor units relate to force of muscle contraction?
larger number of motor unit stimulated, greater force of contraction
79
why is energy required during muscle contraction?
- movement of myosin heads requires energy in the form of ATP
- this enables the sarcoplasmic reticulum to actively reabsorb Ca2+ from the sarcoplasm (to be reused)
80
sources of ATP
- aerobic respiration
- anaerobic respiration
- creatine phosphate
81
how is ATP formed from creatine phosphate?
- creatine phosphate stored in muscle
- phosphate group from creatine phosphate combines with ADP to reform ATP
82
when is creatine phosphate used and why?
- short bursts of vigorous exercise
- ATP can be generated rapidly but the store of phosphate is used up quickly
83
how is creatine phosphate replenished?
phosphate from ATP combines with creatine
84
what happens to the rate of muscle contraction once phosphocreatine has been used up?
rate of muscle contraction = rate of ATP production from both aerobic and anaerobic respiration
85
what two systems make up the fight or flight response?
- autonomic nervous system (sympathetic)
- adrenal-cortical hormonal system
86
how is the flight or fight response activated?
- threat detected by autonomic nervous system
- hypothalamus activates sympathetic nervous system AND adrenal-cortical system by releasing CRF
87
what does the sympathetic nervous system activate in the flight or fight response?
- glands
- smooth muscles
- adrenal medulla (to secrete adrenaline and noradrenaline)
88
what steps does the adrenal-cortical system stimulate?
- pituitary gland to secrete ACTH
- ACTH arrives at adrenal cortex and releases approx 30 hormones
89
seven physical fight or flight responses
- increased heart rate
- pupil dilation (more light, better vision)
- vasoconstriction (in non-vital organs)
- increased glycogenolysis rate
- smooth muscle of airways relaxes
- non-essential systems shut down
- difficulty focusing on small tasks
90
adrenaline mode of action
- adrenaline binds to specific complementary receptor
- activates adenylyl cyclase
- catalyses conversion of ATP to cAMP
- activates protein kinases
- PK phosphorylates and activates other enzymes
- catalyse glycogenolysis
91
which part of the brain controls heart rate?
medulla oblongata
92
two centres of the medulla oblongata
- one increases heart rate by sending impulses through the accelerator nerve (sympathetic nervous system)
- other decreases heart rate by sending impulses through the vagus nerve (parasympathetic nervous system)
93
three types of receptors that affect heart rate
- baroreceptors
- aortic pressure receptors
- chemoreceptors
94
how do baroreceptors control heart rate?
- present in aorta, vena cava, carotid arteries
- detect changes in blood pressure
- low blood pressure, heart rate increases
95
how do chemoreceptors control heart rate?
- present in the aorta, carotid artery, medulla
- detect chemical blood concentration changes such as CO2
96
how do chemoreceptors detect changes in CO2 concentrations?
- CO2 reacts with water in blood to form carbonic acid
- pH of blood decreases
- heart rate increases to increase concentration gradient between capillaries and alveoli and increase rate of diffusion of CO2 into the lungs to be exhaled
97
how is heart rate increased once a stimulus has been detected by a receptor?
- nerve impulses transmitted from the receptor to the medulla oblongata
- centre of the medulla oblongata that increases heart rate increases the frequency of nerve impulses along the sympathetic nerve to the SAN
- higher frequency of waves of electrical excitation transmitted across atria
- increase rate of atrial systole, increase heart rate
98
how is heart rate decreased once a stimulus has been detected by a receptor?
- nerve impulses transmitted from the receptor to the medulla oblongata
- centre of the medulla oblongata that decreases heart rate decreases the frequency of nerve impulses along the parasympathetic nerve to the SAN
- lower frequency of waves of electrical excitation transmitted across atria
- decrease rate of atrial systole, decrease heart rate
99
compare neuronal and hormonal communication
similarities:
- both detect stimuli
- both trigger a response in target cells
- both rely on complementary binding (neurotransmitters vs hormones)
differences:
- neuronal uses action potentials, hormonal used hormones
- action potential transmitted via neurones, hormones transported via bloodstream or ducts
- action potential begins at receptors, hormones secreted from glands
- neuronal uses neurotransmitters to bind to receptors, hormonal uses hormones to bind to receptors
- neuronal is quicker, localised, short-term and hormonal is slower, across body, long-term
100
how is creatine used in muscle contraction? (3 marks)
- when muscle is at rest, ATP donates phosphate to creatine
- during contraction, phosphocreatine donates phosphate to ADP
- because ATP cannot be stored so must be regenerated
101
describe the importance of ATP in muscle contraction. (2 marks)
- myosin head binds to actin-myosin binding site
- ATP binds and breaks cross bridge
- ATP is hydrolysed by myosin/ATPase which forms a cross bridge (allowing myosin to bind to the next site along)
- actively transports Ca2+ back into the sarcoplasmic reticulum
102
what type of proteins are:
- actin
- myosin
- troponin
- actin is fibrous
- myosin is fibrous with globular heads
- troponin is globular
103
what makes up the M line?
tails of myosin
104
how many binding sites are on myosin binding heads and what are they for?
- two binding sites
- one for actin-myosin binding site
- one for ATP
105
what do myosin heads contain?
ATP synthase
