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Year 12 Human Biology > Nervous System > Flashcards

Nervous System Flashcards

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1
Q

Functions of Myelin Sheath

A

insulation, protection and impulse speed increaser

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2
Q

Neurilemma

A

layer that helps in the repair of injured nerve fibres, wrapped around the Schwann cells

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3
Q

Neuromuscular Junction

A

‘synapse’ between an axon and a skeletal muscle cell.

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4
Q

Functional Neuron types

A

Sensory - carry nerve impulses from receptors in sense organs or skin into CNS
Motor - carry nerve impulses from CNS to effectors (muscles and glands)
Interneuron - carry nerve impulses between sensory and motor neurons

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5
Q

Structural Neuron types

A

Multipolar - 1 axon, multiple dendrites, includes most interneurons and motor neurons
Bipolar - 1 axon, 1 dendrite (both may have branches at ends), occur in eye, ear and nose taking impulses from receptors to other neurons
Unipolar - 1 axon (not found in humans)
Pseudounipolar - 1 axon that splits into two extensions (one end with dendrites and the other with dendrites), includes most sensory neurons

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6
Q

Neuron

A

nerve cell

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7
Q

Nerve fibre

A

any long extension of cytoplasm of a nerve cell body - though it usually refers to the axon

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8
Q

Nerve

A

bundle of nerve fibres held together by connective tissue. called tracts within the CNS, nerves outside it

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9
Q

Extracellular fluid contains?

A

high concentration of sodium ions (10x higher outside than in). sodium diffusion = limited due to low number of sodium leakage channels

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10
Q

Intracellular fluid contains?

A

low concentration of sodium ions, but contains potassium ions (30x higher inside than out). potassium diffusion = easy due to high number of potassium leakage channels

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11
Q

Resting Membrane Potential value

A

around -70mV (i.e. potential inside is 70mv less than outside; it is polarised)

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12
Q

RMP cause

A

differences in the distribution of sodium and potassium ions (extracellular fluid = more positive than intracellular)

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13
Q

Sodium-potassium pump

A

carrier protein which moves 2 potassium ions in for every 3 sodium ions removed, i.e. causing a net reduction of positive ions into the cell. against concentration gradient, therefore is active transport and requires ATP

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14
Q

Action potential definition

A

rapid depolarisation and repolarisation of the membrane caused by opening and closing of voltage-gated channels

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15
Q

Depolarisation (AP)

A

sudden increase in membrane potential if level of stimulation exceeds 15mV. some sodium channels are opened (ligand- or mechanical-gated) and sodium ions move into cell. if stimulus is strong enough to increase MP to -55mV, voltage-gated sodium channels open, allowing for independent movement of sodium ions into the cell (all or none response). MP reaches +40mV.

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16
Q

Repolarisation (AP)

A

soon after depolarisation, sodium channels close and voltage-gated potassium channels open, increasing flow of them out of cell. MP decreases again back to -70mV.

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17
Q

Hyperpolarisation (AP)

A

after repolarisation, potassium channels remain open for longer than is needed; MP decreases further than RMP.

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18
Q

Refractory Period

A

once sodium channels are opened, they are quickly inactivated (i.e. unresponsive to stimulus)

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19
Q

Transmission of Nerve Impulse

A

depolarisation of one area causes movement of sodium ions into adjacent areas. this stimulates the opening of voltage gated sodium channels in next part of membrane, initiating a new action potential in said part.

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20
Q

Saltatory Conduction

A

Because ions cannot diffuse in myelinated areas, they simply jump from one node of Ranvier to the next. this allows myelinated fibres to carry nerve impulses faster than unmyelinated ones

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21
Q

Transmission across Synapse

A
  1. nerve impulse activates voltage gated calcium ion channels
  2. calcium ions flow into the cell at the pre-synaptic axon terminal
  3. synaptic vesicles resultantly fuse with the membrane, releasing neurotransmitters by exocytosis
  4. neurotransmitters diffuse across synaptic cleft and attach to receptors.
  5. this stimulates ligand-gated protein channels to open which allow for the influx of sodium ions, initiating a new action potential in the post-synaptic membrane.
22
Q

Thermoreceptors

A

responsive to heat and cold, occurring mainly in the skin.

23
Q

Osmoreceptors

A

responsive to the concentration of substances dissolved in the water of the blood plasma. located in the hypothalamus.

24
Q

Chemoreceptors

A

responsive to particular chemicals. present in the nose - odours, present in the mouth - tastes, present internally - composition of bodily fluids, present in blood vessels - pH of blood and gas concentrations

25
Q

Touch receptors

A

responsive to changes in pressure and vibrations, or simply movements of hairs. found mainly in the skin.

26
Q

Pain receptors

A

responsive to damage to tissues, poor blood flow to tissues, or excessive stimulation of things like chemicals or heat. heavily concentrated in the skin and mucous membranes, most organs except for the brain.

27
Q

Reflex properties

A

rapid, stereotyped, triggered by stimuli and involuntary

28
Q

Protection of the CNS

A

cranium, the meninges and cerebrospinal fluid

29
Q

Meninges

A

layers of connective tissues covering the surface of brain and spinal cord

30
Q

dura mater of meninges

A

outer layer, tough and fibrous (sticks close to cranium but not so much in vertebral canal)

31
Q

arachnoid mater of meninges

A

middle layer, loose mesh of fibres

32
Q

pia mater of meninges

A

inner layer, more delicate and contains many blood vessels

33
Q

cerebrospinal fluid

A

clear, watery fluid containing a few cells aswell as urea, glucose, protein and salts. it acts as a shock absorber, it suspends the brain and provides nutrients/ gets rid of wastes

34
Q

Cerebrum

A

cerebral cortex: thinking, reasoning, learning, memory, intelligence and sense of responsibility, perception of senses and initiation and control of voluntary muscle contraction
sensory areas interpret impulses from receptors, motor areas control muscular movements and association areas are concerned with intellectual and emotional processes

35
Q

basal ganglia

A

grey matter deep inside the cerebrum, play a role in initiating desired movements and inhibiting unwanted ones.

36
Q

frontal lobe

A

thinking, problem solving, emotion, personality, language, control of movement

37
Q

parietal lobe

A

processing temperature, touch, taste pain and movement

38
Q

temporal lobe

A

processing memories and linking them with senses, receives auditory information

39
Q

occipital lobe

A

vision

40
Q

insula

A

recognition of different senses and emotions, addiction and psychiatric disorders

41
Q

corpus callosum

A

joins left and right hemispheres of the brain allowing for communication between them

42
Q

cerebellum

A

under rear part of cerebrum, controls posture, balance, fine coordination of voluntary muscle movement.

43
Q

hypothalamus

A

control homeostasis and many bodily activities, including blood pressure and heart rate, body temperature, contraction of bladder, sleeping, food and water intake, endocrine system, emotion

44
Q

medulla oblongata

A

continuation of the spinal cord, contains the cardiac centre, respiratory centre and vasomotor centre, which respectively control the rate and force of heartbeat, the rate and depth of breathing and the diameter of blood vessels

45
Q

ascending tracts (spinal cord)

A

sensory axons carrying impulses upwards towards the brain

46
Q

descending tracts (spinal cord)

A

motor axons carrying impulses downwards away from the brain

47
Q

division of peripheral nervous system

A

afferent and efferent

48
Q

afferent division

A

involves sensory neurons carrying impulses into the CNS
somatic sensory neurons carry impulses from the skin and muscles.
visceral sensory neurons carry impulses from the internal organs

49
Q

efferent division

A

involves motor neurons carrying impulses away from the CNS
autonomic division involves carriage of impulses to heart muscle, involuntary muscles and glands. (2 neurons)
somatic division involves carriage of impulses to skeletal muscles (1 neuron)

50
Q

autonomic division (efferent)

A

sympathetic - fight or flight, activated when in times of strenuous activity, prepares body for such times. neurotransmitter involved = acetylcholine
parasympathetic - rest and digest, activated when in times of quiet activity; more regular bodily activities, controlling its constant, internal environment. neurotransmitter involved = noradrenaline

Year 12 Human Biology (4 decks)

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