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Human Biology > Nervous System > Flashcards

Nervous System Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What matter is myelinated; white or grey?

A

Grey matter is unmyelinated. White matter is myelinated.

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2
Q

What are the 3 ways of protection for the central nervous system?

A

The CNS is protected by:
Bones of the cranium and vertebral canal.
The meninges; dura, arachnoid, pia
Cerebrospinal Fluid.

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3
Q

What does cerebrospinal fluid do?

A

Protection (acts as shock absorber).
Support (buoyancy).
Transport/Nutrition.

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4
Q

Where is CSF formed? What does it contain? What happens to the excess CSF?

A

CSF is formed from blood (in brain ventricles).
Contains a few cells and some glucose, protein, urea and salts.
Excess is reabsorbed back into blood vessels.

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5
Q

What is the basic structure of the cerebrum?

A

Lobes named according to the cranial bones that cover them.
Cerebral Cortex is 2-4 mm grey outer layer of cerebrum.
White matter deep inside cerebrum. Basal Ganglia are internal grey matter. Between the grey cerebral cortex and the grey basal ganglia are bundles of myelinated white fibres.

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6
Q

What are the white fibre bundles called in the CNS? What are they called outside the CNS

A

Within the CNS, these bundles of white fibres are called tracts. Outside the CNS, they’re called nerves.

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7
Q

What do the tracts in the brain do?

A

Connect cortex areas within the same hemisphere.
Connect left and right hemispheres.
Connect cortex to other parts of brain or to the spinal cord.

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8
Q

What are the 6 cerebral cortex function?

A 
Thinking, reasoning, learning.
Memory.
Intelligence.
Sense of Responsibility.
Perception of the senses.
Initiation and control of voluntary muscle contraction.
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9
Q

What are the functional areas of the cerebral cortex?

A

Sensory Areas – interpret impulses from receptors.
Motor Areas – control muscular movements.
Association Areas – concerned with intellectual and emotional processes.

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10
Q

What is the Corpus Callosum? What does it do?

A

It is a wide band of nerve fibres that lies underneath the cerebrum at the base of the longitudinal fissure.
Nerve fibres in the Corpus Callosum connect the left and right hemispheres of the brain.

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11
Q

What is the cerebellum responsible for?

A

Exercises control over posture and balance.

Co-ordination of voluntary muscle movement.

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12
Q

How does the cerebellum control posture, balance and co-ordination?

A

It receives sensory information from the inner ear for posture and balance.
It receives sensory information from stretch receptors in the skeletal muscles.
All processes are sub-conscious.

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13
Q

What happens to the body’s movement if the cerebellum is damaged?

A

Movements still occur but are spasmodic, jerky and uncontrolled.

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14
Q

Where is the hypothalamus? What is it responsible for?

A

It lies in the middle of the brain. It is mainly concerned with homeostasis.

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15
Q

What does homeostasis regulate?

A 
The autonomic nervous system (HR, BP, digestive juices, movement of alimentary canal, pupil diametre).
Body Temperature.
Food & Water Intake.
Patterns of waking & sleeping.
Contractions of urinary bladder.
Emotional Responses.
Secretion of hormones.
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16
Q

What is the medulla oblongata? What does it do?

A

It is a continuation of spinal cord just below base of brain.
It automatically adjusts many body functions.
It contains Cardiac, Respiratory, Vasomotor and Expulsion Centres.

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17
Q

What is the spinal cord? Is its protection similar to the brain?

A

Cylindrical tube from the foramen magnum to L2.
Approximately 44 cm long.
Has same protection as brain EXCEPT dura mater (outer meninges) is not attached to bone. Instead, layer of fat + vessels + connective tissue cushions.

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18
Q

What does the spinal cord contain?

A

Grey and white matter reverse of that in brain.
White matter surrounds grey ‘H’ or ‘butterfly’ central region.
Central canal contains CSF.
Myelinated nerve fibres arranged in bundles and called tracts.

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19
Q

What does the ascending and descending tracts do?

A

Ascending tracts carry impulses towards brain.

Descending tracts carry impulses away from brain.

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20
Q

What are the different parts of the brain?

A

Parietal, frontal, occipital, temporal, cerebellum, brain stem (mid-brain, pons, medulla oblongata), thalamus, hypothalamus, olfactory bulb, corpus callosum.

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21
Q

What are the functional types of neurons?

A

Afferent, efferent and interneuron (connector).

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22
Q

What are the structural types of neurons?

A

Multipolar (one axon, multiple dendrites; interneurons in the brain/spinal cord & most motor neurons to the skeletal muscles), bipolar (one axon, one dendrite; eye, ear & nose, impulses from the receptor to other neurons) & unipolar (one axon, cell body is on one side of the axon; most sensory neurons).

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23
Q

What is a synapse?

A

A synapse is the junction between to adjacent neurons, impulses must cross the synapse.

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24
Q

What does the nervous & endocrine systems work together to do?

A

Communicate, integrate, co-ordinate.

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25
Q

What does the central nervous system consist of?

A

The brain & spinal cord.

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26
Q

What does the peripheral nervous system consist of?

A

All the nerves attached to the central nervous system (crania; & spinal nerves).

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27
Q

What are afferent neurons? What do they do?

A

They are sensory neurons (eyes, ears, touch, taste, etc). They carry messages towards the CNS.

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28
Q

What are efferent neurons? What do they do?

A

They are motor neurons. They carry messages away from the CNS.

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29
Q

What are neurons?

A

They are the basic structural unit of the nervous system. They are specialised cells and have a specialised structure.

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30
Q

What do neurons consist of?

A

Dendrites, Node of Ranvier, myelin sheath, axon, Schwann cells,axon terminal, soma (cell body).

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31
Q

What are the 3 types of neurons?

A

Afferent, efferent, interneuron.

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32
Q

How do nerve impulses travel?

A

They only travel in one direction along a neutron. They travel from dendrites to the cell body and the to the axon.

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33
Q

What is the basic root of a reflex arc?

A

The sensory receptors detect a stimulus (a ganglion occurs on this root), the impulse travels along the dorsal root, it ten travels along past a synapse to an interneuron in the spinal cord, then to the motor neuron. This motor impulse travels along the ventral root, to the muscle need to react, this is called the effector.

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34
Q

What are reflexes?

A

They are the rapid, automatic response to a stimulus.

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35
Q

All reflexes:

A

Require a stimulus, are involuntary, are rapid, are stereotyped (occur in the same way each time).

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36
Q

What are spinal reflexes?

A

They are reflexes carried out by the spinal cord; no brain involvement is required.

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37
Q

What do spinal reflexes consist of?

A

A receptor, a sensory neutron, at least one synapse, a motor neuron and an effector (muscle/gland).

38
Q

What do receptors do? Are they complex?

A

They detect changes in the bodies internal/external environment. Some receptors are simple nerve endings, whilst others are grouped together to form a sense organ.

39
Q

Name 4 different types of receptors and name what they do.

A

Thermoreceptors; heat/cold
Osmoreceptors; sensitive to the concentration of substances dissolved in the water of blood plasma
Chemoreceptors; chemicals
Touch receptors; very light touch (skin)
Pain receptors (nocireceptors); stimulated by damage to tissue, mainly found on skin & mucous membranes, they warn us that damage is occurring; they don’t adapt

40
Q

What is the name of the reflexes we know from birth?

A

Protective reflexes.

41
Q

Can you acquire reflexes?

A

Yes, some complex motor patterns can be learnt; these are called acquired reflexes, these are often learnt through repetition (e.g. bike riding, catching a ball etc).

42
Q

What happens when positive and negative charges come together? What happens if they get separated?

A

Energy is released. The unlike shared have the potential to come together and release energy.

43
Q

What is the potential difference between these two shared measured in?

A

Volts or millivolts.

44
Q

What is the potential difference across the membrane of a neuron called? And what is it? What is its mV when resting?

A

The membrane potential. It is the difference in ion concentrations between the inside and the outside of a neuron. The resting membrane potential is -70mV (inside = 70 mV less than the outside).

45
Q

What are the ions that create this potential? And what are their concentrations?

A

Sodium (Na+) and potassium (K+). Na is 10 times high on the outside than the inside. K is 30 times greater on the inside than the outside.

46
Q

Which ion is the neuron membrane most permeable to? What does this mean for the charge of the neuron?

A

Potassium, meaning it easily diffuses out of the neuron. This leaves the inner neuron negatively charged.

47
Q

What maintains this resting potential? How does it do this?

A

The sodium-potassium pump. It pumps some sodium ions out and some potassium ions into the neuron.

48
Q

Why if both ions are positive, is the charge of the neuron negative?

A

There is not enough K inside to counteract the Na outside, meaning the inside is negative.

49
Q

What is the neuron said to be if the resting membrane potentials is maintained?

A

Polarised.

50
Q

How does the neuron depolarise?

A

A strong stimulus (larger than 15 mV) must be applied to the nerve fibre. this means the membrane becomes permeable to Na+ and it begins to move in. This movement is too great to be balances by an outward movement of K+; meaning the charges become reversed (positive on the inside, negative on the outside).

51
Q

What happens after depolarisation is achieved?

A

The neuron closes the Na+ gates and the sodium-potassium pump restores the neuron’s charge back to normal. This is called repolarisation.

52
Q

What is action potential?

A

The act of depolarisation followed by repolarisation. This is basically what a nerve impulse is.

53
Q

What is the refractory period?

A

The time during and just after an action potential, the neuron cannot respond to another stimulus.

54
Q

What happens if the action potential occurs along an unmyelinated fibre?

A

It simply moves along the length of the fibre.

55
Q

What happens if the action potential occurs along an myelinated fibre?

A

The myelin insulated the neuron membrane so that the ions cannot diffuse through it. The impulse leaps from one Node of Ranvier to another. This is called saltatory conduction

56
Q

What is the speed at which an impulse passes through a myelinated and unmyelinated fibre?

A

Myelinated: 140 m/sec
Unmyelinated: 2 m/sec

57
Q

What is the difference between a large and small stimulus?

A

Large stimuli cause more neurons to be depolarised. They cause more neurons to depolarised after the refractory period.

58
Q

How do impulses travel across a synapse?

A

When the pre-synaptic know depolarises, it causes an influx of calcium (Ca++), this results in the release of a neurotransmitter from vesicles. This neurotransmitters are able to diffuse across the synapse and increase Na permeability of the post-synaptic membrane. This initiates depolarisation.

59
Q

Name 4 neurotransmitters.

A

Acetylcholine, adrenaline, dopamine, histamine.

60
Q

What chemicals affect transmission of impulses? What do they do?

A

Caffeine & benzedrine stimulate transmission.
Anaesthetics & hypnotics depress transmission.
Venom affects transmission at the neuromuscular junction.
Nerve gas can build up acetylcholine at neuromuscular junction (equalling constant stimulation of the muscle)

61
Q

What are the divisions of the peripheral nervous system?

A

Afferent; somatic and visceral

Efferent; autonomic (sympathetic and parasympathetic) and somatic

62
Q

What does the autonomic system (in the efferent division of the nervous system) include? Does it occur consciously or subconsciously?

A

Nerves that carry messages to the heart, involuntary muscles, glands and other internal body organs. It occurs sub-consciously.

63
Q

What does the autonomic system maintain?

A

It maintains homeostasis.

64
Q

What does the autonomic system regulate?

A

Heart rate, blood pressure, body temperature, digestion, energy production, pupil diameter, airflow to lungs, defaecation and urination.

65
Q

How does the ANS work?

A

It has some cranial nerves and some spinal nerves. Two neurons carry the impulse to the effector (muscle or gland). One neuron has its cell body in the spinal cord, the other has its cell body outside the spinal cord in a ganglion.

66
Q

What neurotransmitters are present in the sympathetic division?

A

Acetylcholine at the first synapse, and then mainly norepinephrine/noradrenaline at the second synapse

67
Q

What neurotransmitters are present in the parasympathetic division?

A

Acetylcholine at the first and second synapses.

68
Q

What neurotransmitters are present in the somatic (efferent) division?

A

The neurons (voluntary) release acetylcholine at their junction with skeletal muscles.

69
Q

What are the two autonomic nerve fibres?

A

Parasympathetic and sympathetic

70
Q

How do the organs receive these impulses?

A

Through acetylcholine or noradrenaline (at the second synapse)

71
Q

What is the sympathetic division for?

A

It prepares the body for strenuous activities; “fight or flight”.
It allows the body to react to a crisis.

72
Q

What are the sympathetic responses?

A 
Increased heart rate and force of contraction
Dilated bronchioles
Decreased digestion/saliva production
Increased blood glucose levels
Dilated pupils
Increased sweat production
Peripheral vasoconstriction
More blood to heart, lungs and muscles
Stimulated adrenalin release
Relaxes bladder
73
Q

What is the parasympathetic division for?

A

It maintains the body during relatively quiet/restful conditions; “rest and digest”. It enables the body to adjust to calm situations.

74
Q

What are the parasympathetic responses?

A

Decreases heart rate and force of contraction
Constricts bronchioles
Increases digestion/saliva production
Decreased blood glucose levels
Constricts pupils
Constricts bladder muscles
Little effect on sweat glands, blood vessels and adrenalin release

75
Q

How does the nervous system parts work together?

A

Motor neurons that are part of the efferent division of the PNS carry impulse to muscle fibres. The cell bodies of these motor neurons are located in the brain or the spinal cord. The axons extend out to the muscle fibres. At the muscle end of the axon, it divides into many branches. These branches (axon terminals) attach to individual fibres of the muscle. Meaning, one impulse along a neuron can cause man fibres to contract.

76
Q

What is the neuromuscular junction?

A

It is the point at which a motor impulse is passed to a muscle fibre.

77
Q

What is a motor end plate?

A

The presynaptic knob of the neuron fits that into the depression in the muscle fibre.

78
Q

How do the muscles get stimulated? Which neurotransmitter is the most common?

A

The neurotransmitter that was released from the presynaptic vesicles, diffuses across the synapse (neuromuscular junction), this stimulates the muscle fibres. The most common neurotransmitter is acetylcholine.

79
Q

When is acetylcholinesterase release? What is it?

A

It is an enzyme released from the post-synaptic membrane after the neurotransmitter (acetylcholine) has diffused across the synapse. Acetylcholinesterase deactivated acetylcholine very quickly.

80
Q

What do the motor pathways of the upper neuron include?

A

Cell body in the cerebrum or sometimes spinal cord.

81
Q

What do the motor pathways of the lower neuron include?

A

Cell body in the spinal cord.

82
Q

What motor neuron is used from voluntary movement?

A

The cell body of the upper motor neuron in the cerebrum.

83
Q

What motor neuron is used from involuntary movement?

A

The cell body of the upper neuron in the cerebellum and some other parts of the brain or spinal cord.

84
Q

What is balance required for? What controls it?

A

Balance is required for constant adjustments to the contraction and relaxation of muscles. The cerebellum controls it.

85
Q

What does the cerebellum receive input from? And what information is received from these centres?

A

The cerebrum; information about conscious awareness of the body’s position
The semi-circular canals of the inner ear; movements of the head
The saccule and utricle of the inner ear; the position of the head
The eyes
Pressure receptors in the skin
Stretch receptors

86
Q

How do we move?

A

Association tract in the cortex plans impulse
Motor tract in the cortex initiates impulse
Cerebellum integrates & co-ordinated impulses, permitting fine motor movements, posture & balance
Cerebellum receives other inputs from the inner ear to assist in posture & balance
Stretch receptors also provide information to the cerebellum
Motor neurons relay information
Neuromuscular junction relays to muscle

87
Q

What parts of the brain are responsible for the senses?

A

The temporal lobe is responsible for auditory
The parietal lobe is responsible for the motor (stretch) and sensory (pressure receptors in skin)
The occipital lobe is responsible for vision

88
Q

What are sulcus?

A

Grooves in the brain.

89
Q

What are convolutions?

A

The fold of the brain, they provide more surface area.

90
Q

What are gyrus?

A

They are the bumps of the brain.

91
Q

What is the large sulci/fissure?

A

The large fold in the middle of the brain.

92
Q

What is a mixed nerve?

A

A nerve which contains both efferent and afferent/motor and sensory nerves.

Human Biology (5 decks)

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