Module 5.1.1 - Neuronal communication Flashcards

(81 cards)

1
Q

What is homeostasis?

A

Maintenance of relatively constant conditions inside the body

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2
Q

What are some external changes to the environment?

A
  • temp
  • soil pH
  • light intensity
  • loud noises
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3
Q

What are some internal changes to the environment?

A
  • pH in blood
  • blood glucose
  • temp
  • water potential
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4
Q

Do plants have a nervous system?

A

No but can still respond to changes in environment to survive

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4
Q

How to animals react to change?

A

Electrical responses via neurones and chemical responses via hormones

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4
Q

How do plants react to change?

A

Chemical responses via hormones

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5
Q

What is the nervous system?

A

Electrical impulses that detect changes/stimuli

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6
Q

What is a motor neurone?

A

Transmits impulses from relay or sensory neurones to an effector

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7
Q

What is a relay neurone?

A

Transmits impulses between neurones

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8
Q

What are parts of a relay neurone?

A

Cell body, dendrons, axons, nucleus, dendrites

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8
Q

What are parts of a motor neurone?

A

Cell body, dendrites, cytoplasm, nucleus, myelin sheath, axon, node of Ranvier, axon terminals

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9
Q

What is a sensory neurone?

A

Neurone that transmits impulses from receptor cell to relay or motor neurone or brain

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10
Q

What are parts of a sensory neurone?

A

Dendrites, dendron, myelin sheath, nucleus, cytoplasm, neurotransmitters, cell body, axon, node of Ranvier, axon terminal

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11
Q

What is the process from stimuli to response?

A

Stimuli, receptor, sensory neurone, relay neurone, motor neurone, effector, response

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12
Q

What are Schwann cells?

A

Produce large layers of plasma membrane around an axon, called myelin sheath
- type of glia cells

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12
Q

What is saltatory conduction?

A

Impulse jumping from each node of Ranvier (small gap in between each myelin sheath) to the next

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13
Q

What is multiple sclerosis?

A

Impaired Schwann cells, brain detects myelin as foreign so breaks it down, own immune system damages you
- results in loss of muscle control, vision and balance

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14
Q

What are sensory receptors?

A

Allow body to detect changes in environment, often located in sense organs, specific to 1 type of stimulus

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15
Q

What do sensory receptors act as?

A

Transducers

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16
Q

What are transducers?

A

Sensory receptors convert stimulus into nerve impulses called generated potential, this is then passed through nervous system to brin a response by sending out impulse to an effector - action potential

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17
Q

What are Pacinian corpuscle?

A

Specific sensory receptors that detect mechanical pressure
- located deep within the skin, most abundant in fingers and soles of feet

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18
Q

How does depolarization in Pacinian corpuscles happen?

A

Pressure is applied/ stimulated which widens the stretch median sodium channels, allowing sodium ions to enter which makes the cell positive
- generated potential is created
- a nerve impulse/action potential is then generated

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19
Q

What is resting potential?

A

Outside of membrane is more positive than outside, is polarized, around -70mV

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20
Q

What is action potential?

A

Stimulus detected by sensory receptor, energy of stimulus temporarily reverses charge on axon membrane, potential difference across membrane is +40mV, depolarized, when impulse passes is repolarizes neurone back to resting potential

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21
What is the refractory period?
After action potential, short period of time when axon cannot be excited again, voltage gated sodium ion channels remain closed
22
Why is the refractory period importnat?
Make sure action potential travels in 1 direction and they don't overlap
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How can action potential be sped up?
- myelination - axon diameter, less resistance to flow of ions in cytoplasm if large axon diameter - temperature, diffuse faster at high temp but will denature if too high
24
What is the all or nothing principle?
Nerve impulses said to be all-or-nothing response, threshold value must be reached to trigger a response, no matter the stimulus the same sized action potential will be triggered
25
What is a synapse?
Junction between 2 neurones or a neurone and effector
26
What do synapses do?
- ensure impulse is unidirectional - impulse from 1 neurone to be transmitted to many - impulses from many neurones to be transmitted to 1
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How do synapses work?
1. action potential causes voltage gated calcium channels to open, influx calcium ions down electrochem gradient 2. vesicles fuse with pre synaptic membrane, voltage gated sodium channels on post synaptic membrane 3. neurotransmitters bind to receptors on v-g Na+ channels and they open 4. influx Na+ ions down electrochem gradient, +ve charge causes depolarisation , generate action potential
28
What is ACH and ACHE?
ACH - acetylcholine is a neurotransmitter ACHE - acetylcholinesterase is an enzyme that breaks down ACH that's binded to receptors
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What does ACHE do?
- breaks down ACH into choline and acetyl that diffuse down conc gradient into pre sysnaptic neurone - ATP energy creates bonds between choline and acetyl to create ACH - it is repackaged in ER as a vesicle
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What are the 2 types of neurotransmitters?
- excitatory - inhibitory
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What is the neurotransmitter excitatory?
Results in depolarisation of post synaptic neurone. If threshold reached in post synaptic membrane, action potential is triggered. e.g. ACL
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What is the neurotransmitter inhibitory?
Results in hyperpolarisation of post synaptic membrane. Prevents action potential from being triggered e.g. Gamma aminobutyric acid
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What are the 2 types of summation?
- temporal - spatial
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What is temporal simmantion?
Constant firing of neurotransmitters from 1 pre synaptic neurone
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What is spatial summation?
Multiple pre synaptic neurones working together to reach threshold for action potential
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What are the top 2 parts of the nervous system?
Central nervous system Peripheral nervous system
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What 2 nervous systems come from the peripheral nervous system?
Somatic NS Autonomic NS
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What is in the CNS?
- brain - spinal chord - relay neurone
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What is in the peripheral NS?
- nerves around the body - sensory and motor neurone - Pacinian corpuscle
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What is the somatic NS?
Conscious control - speech - movement
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What is the autonomic NS?
Subconscious control - breathing - blinking - swallowing - heartbeat - digestion - vomiting
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What 2 nervous systems come from the autonomic NS?
Sympathetic NS Parasympathetic NS
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What is the sympathetic NS?
Fight or flight response - uses noradrenaline (NA)
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What is the parasympathetic NS?
Relaxing response - uses Acetylcholine (ACH)
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What are the parts of the brain?
- cerebrum - cerebellum - medulla oblongata - pituitary gland - hypothalamus
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What us the cerebrum?
- voluntary actions - highly folded to increases SA and capacity for complex activity - split into 2 hemispheres, each receive impulses from opposite sides of body
47
Whatv are the lobes of the cerebrum and what do they do?
Frontal lobe - motor function, problem solving, memory, language, judgement, behaviour, personality Parietal lobe - integrating sensory info, taste, smell Temporal lobe - listening, general speech perception, communication Occipital lobe - visual processing
48
What is the cerebellum?
- controls muscular movement, posture and balance - doesn't initiate movement but just coordinates it - receives info from ears about balance and tone of muscles and tendons from the body
49
What is the medulla oblongata?
- controls reflex activities such as heart rate, breathing rate - important in autonomic nervous system, controlling swallowing, coughing, sleep and peristalsis
49
What is the hypothalamus?
- controls hormones and homeostasis - controls pituitary gland, temperature and blood pressure
50
What is the pituitary gland?
- anterior pituitary (front) secretes hormones and produces them - posterior pituitary (back) stores hormones and releases them to hypothalamus
50
What is a reflex action?
Involuntary response to a sensory stimulus
50
Why are reflexes important for survival?
- avoid harm of body or reduce severity of harm - leaves brain to deal with more complex responses because they're involuntary, prevent brain overload - present at birth, don't have to be learnt, provide immediate protection - reflex arc is short and fast - many are every day actions
51
What is the reflex arc pathway?
- receptor detects stimulus and creates action potential - sensory neurone carries impulse to spinal chord - relay neurone connects sensory and motor neurone - motor neurone carries impulse to effector - response is carried out
52
What is a knee-jerk reflex?
- spinal reflex, from spinal chord not brain - commonly used by doctors
53
What is the blinking reflex?
- cranial reflex so only occurs in brain not spinal chord - both eyes will blink when cornea is stimulated
54
What muscle causes the eye to blink?
Orbicularis oculi
55
What is the blinking reflex pathway?
- stimulus in cornea triggers an impulse - impulse sent along sensory neurone - passes through relay neurone in lower brain stem - sent along branches of motor neurones - response is triggered of closing eyes
56
What are the 3 types of muscles and are they voluntary or involuntary??
cardiac - involuntary skeletal - voluntary smooth - involuntary
56
What is a muscle fibre?
cell
57
What is the sarcomere?
- functional region of myofibrils, it contracts when a muscle contracts - contains actin, myosin, light band, dark band, H zone, Z line,
57
What contained in the skeletal muscle?
- lots of mitochondria to provide ATP for muscle contractions - sarcolemma which is the specialised plasma membrane for muscle cells - sarcoplasm reticulum contains calcium ions needed for muscle contractions - striated/stripey myofibrils - t tubules, extensions of sarcolemma, help spread electrical impulses through sarcoplasm - sarcoplasm is the shared cytoplasm within a muscle fibre
58
What are myofibrils?
- long cylindrical organelle, made up of protein, specialised for contraction - myosin is a thicker filament, long tod shaped fibred with bulbous heads that project to 1 side - actin is a thinner filament, 2 strands twisted around each other
59
What are parts of the sarcomere?
- Z line will move closer together with contractions - light band contains actin only - dark band contains actin and myosin - H zone contains only myosin which narrows with contractions
60
What are the 2 types of twitch fibres?
Slow and fast
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What is the cardiac muscle?
- found only in heart, myogenic so heart beats regularly - specialised striated - involuntary - intermediate contraction speed'- intermediate contraction length
61
What is the skeletal muscle?
- makes up bulk of body muscle tissue and is responsible for movement -straited - voluntary - rapid contraction speed - short contraction length
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What is the smooth muscle?
- found in many parts of body, e.g. walls of hollow organs like stomach and blood vessels - non straited - involuntary - slow contraction speed - can remain contracted for a very long time
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What is the sliding filament model?
Where actin and myosin filaments slide past each other to contract and cause movement
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What is tropomyosin?
- covers binding sites on actin in resting state - held in place by troponin (protein)
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How does the sliding filament model work?
1. (stimulation) - tropomyosin covers binding site - held in place by troponin - ADP attached to myosin bulbous heads 2. - action potential arrives - depolarisation of sarcoplasmic reticulum + sarcolemma - voltage gated Ca2+ channels open 3. - Ca2+ diffuses through sarcoplasm - binds to troponin - conformational change, exposes binding sites on actin 4. (attachment) - myosin head binds to actinmyosin binding site - forming cross bridges 5. - myosin head flexes to pull actin alonh - releases ADP 6. (detachment) - ATP binds to myosin head - detaches from actin 7. - Ca2+ activates ATPase on myosin head - hydrolyses ATP to ADP + Pi - energy released returns myosin head to original position
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What are the 3 stages of the sliding filament model?
- stimulation - attachment - detachment
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