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Biology > UNIT 3: The Human Nervous System > Flashcards

UNIT 3: The Human Nervous System Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

central nervous system

A

composed of the brain and spinal cord

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2
Q

peripheral nervous system

A

composed of all the nerves not found within the boundaries of the central nervous system as well as the collections of nerve cells called ganglia.

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3
Q

neuron

A

nerve cell specialised to carry electochemical impulses.

functional unit of the human nervous system

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4
Q

sensory neurons

A

carry impulses towards the central nervous system

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5
Q

interneurons

A

carry impulses from one neuron to another completely within the central nervous system

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6
Q

motor neurons

A

carry impulses from the interneuron to an effector

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7
Q

effector

A

an organ or tissue that carries out an action in response to a signal from the nervous system

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8
Q

neuron cell components: dendrites

A

receive impulses from other neurons and transmit the impulse towards the cell body

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9
Q

neuron cell components: cell body

A

located between the dendrites and axon. it is responsible for the upkeep of the cell and for producing neurotransmitter substances

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10
Q

neuron cell components: neurotransmitter

A

chemical substance released by a neuron to transmit a nerve impulse to another neuron or effector

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11
Q

neuron cell components: axon

A

carries impulses away from the cell body towards axon terminals

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12
Q

neuron cell components: myelin sheath

A

layers of lipids formed from a schwann cell that wrap around the axon and dendrites or neurons. It insulates the axon / dendrite maintaining and speeding up the electrochemical impulse.

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13
Q

neuron cell components: schwann cell

A

produces myelin sheath

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14
Q

neuron cell components: axon terminals

A

present at the end of the axon and contain synaptic vesicles which contain neurotransmitters

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15
Q

neuron cell components: synaptic vesicles

A

contain neurotransmitter chemicals. They fuse with the cell membrane when an impulse reaches the axon terminal. this releases the neurotransmitter

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16
Q

nerve impulse

A

a short-lived electrochemical signal that travels along neurons via movement of chemical ions into and out of the neuron

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17
Q

transmission of the nerve impulse to another neuron

A

occurs at synapses

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18
Q

synapses

A

structure where 2 neurons come into close contact so that a nerve impulse can be transmitted between the 2 neurons

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19
Q

transmission process

A
  • nerve impulse arrives at an axon terminal (presynaptic neuron).
  • synaptic vesicles are stimulated to fuse with the cell membrane.
  • neurotransmitter chemicals are released from the vesicle into the gap between the 2 neurons, called the synaptic cleft; examples of neurotransmitter substances include: acetylcholine, noradrenaline and dopamine.
  • once a neurotransmitter is in the synaptic cleft it travels the short distance to the dendrite of the postsynaptic neuron where it stimulates the cell membrane to allow ions to flow inwards, setting up a new electrochemical impulse.
  • the neurotransmitter is then either broken down by enzymes or reabsorbed into the presynaptic neuron.
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20
Q

functions of the synapse

A
  • allow transmission of the impulse from one neuron to another.
  • control the direction of the impulse - the impulse cannot travel backwards.
  • acts as junction allowing the impulse to be split up and travel along many different neurons or join many impulses together into one impulse
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21
Q

conjunctiva

A

produces mucous protecting the front of the eye

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22
Q

cornea

A

transparent part of the sclera that protects the front of the eye; it also allows light tot enter the eye and refracts the light rays slightly as part of focusing light into the retina

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23
Q

iris

A

coloured part of the eye.

type of smooth muscle that can contract and relax in response to the amount of light entering the eye

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24
Q

pupil

A

hole in the internal part of the eye just behind the iris. it allows light into the eye and its size is controlled by the iris. it appears black due to light entering and not leaving the eye as it is all absorbed

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25
Q

aqueous humour

A

watery liquid present just inside the cornea that gives shape to the front of the eye

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26
Q

vitreous humour

A

viscous liquid present inside the eye ball that maintains the shape of the eye by maintaining outward pressure on the sclera.

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27
Q

ciliary body

A

type of smooth muscle surrounding the lens that can contract and relax changing the shape of the lens as part of focusing light on the retina

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28
Q

suspensory ligament

A

attaches to and surrounds the ciliary body providing a lever for the contraction of the ciliary muscle

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29
Q

lens

A

transparent structure held in place by the ciliary body and suspensory ligament; changes shape in response to contraction and relaxation of ciliary body. responsible for focusing light on the retina

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30
Q

sclera

A

white of the eye covering the entire eyeball except the front part, protects the eye and acts as the attachment surface for external muscles that move the eye in different directions

31
Q

choroid

A

heavy pigmented layer lying between the retina and sclera, absorbs all of the light entering the eye and helps to prevent reflection within the eye

32
Q

retina

A

light-sensitive structure of the eye; contains rods and cones; rods are sensitive to only black and white and cones are sensitive to red, green and blue light.

33
Q

fovea

A

region of the retina where all of the light rays converge when you look directly at an object, mostly composed of cones

34
Q

blind spot

A

region of the retina where all the nerve fibres from the retina converge and exit the eye and travel to the brain; there are no light-sensitive cells in this region

35
Q

optic nerve

A

collection of sensory neurons that carry messages to the brain from the retina

36
Q

long-sightedness (hyperopia): symptom

A

near objects appear blurred

37
Q

long-sightedness (hyperopia): cause

A

eyeball is either too short or the focusing elements are too weak

38
Q

long-sightedness (hyperopia): treatment

A

convex lens placed in front of the eye

39
Q

short-sightedness (myopia): symptom

A

distant objects appear blurred

40
Q

short-sightedness (myopia): cause

A

eyeball is either too long or the focusing elements are too strong

41
Q

short-sightedness (myopia): treatment

A

concave lens in front of the eye

42
Q

outer ear

A

composed of the pinna and auditory canal.

these pick up sound waves and channel them to the eardrum

43
Q

middle ear

A
  • the sound waves arrive at the eardrum and are transferred into the 3 small bones of the ear - the ossicles - hammer, anvil and stirrup.
    they transfer sound waves onto the inner ear.
    they can amplify soft sounds and dampen loud sounds.
  • the eustachian tube is connected to the throat so that pressure differences can be equalised during swallowing preventing damage to the eardrum
44
Q

inner ear

A

functions in both hearing and balance

composed of cochlea & vestibular apparatus

45
Q

cochlea

A
  • receives sound vibrations from the ossicles via the oval window.
  • it is filled with lymph through which the sound waves pass.
  • there are hair cells within the inner wall of the cochlea that sense the vibrations of the lymph and convert these vibrations into electrical impulses that are then sent to the brain via the auditory nerve.
  • finally, there is a round window below the oval window that vibrates with an opposite phase to the round window allowing vibrations to be transferred within the lymph more efficiently
46
Q

vestibular apparatus

A
  • consists of 3 semicircular canals filled with lymph.
  • each canal has hair cells lining its internal walls.
  • as the head moves, the lymph moves within the canals stimulating the hair cells.
  • the movement of the lymph is converted into electrical impulses by the hair cells and these impulses are transferred to the brain via the vestibular nerve
47
Q

glue ear: symptom

A

inflammation of the middle ear, muffled hearing and pus formation

48
Q

glue ear: cause

A

infections by viruses and/or bacteria

49
Q

glue ear: treatment

A

ear drops or a grommet for severe infections

50
Q

smell

A

also called olfaction.
occurs in the nasal cavity.
there are specialised cells called olfactory receptor cells.
this group of cells senses the odours and sends signals to the brain via the olfactory bulb and olfactory nerve

51
Q

taste

A

5 basic tastes: sweet, sour, salt, bitter & umami.

52
Q

brain

A

composed of:

  • cerebrum
  • cerebellum
  • medulla oblongata
  • hypothalamus
  • pituitary gland
53
Q

cerebrum

A
  • largest part
  • composed of 2 symmetrical hemispheres.
  • high folded surface giving extra area for neurons.
  • divided into different lobes: frontal, temporal, parietal, occipital
54
Q

frontal lobe

A

functions in reasoning, short-term memory, intelligence, personality, problem-solving, emotion & language.

55
Q

temporal lobe

A

functions in long-term memory, speech & hearing

56
Q

parietal lobe

A

functions in movement & touch

57
Q

occipital lobe

A

functions in vision

58
Q

cerebellum

A
  • located at the back of the brain

- functions in control and coordination of movement.

59
Q

medulla oblongata

A
  • belongs to the brainstem (on top of the spinal cord).

- functions in breathing, heart rate, blood pressure, vomiting, coughing, sneezing & swallowing

60
Q

hypothalamus

A
  • small region of the brain located just above the brain stem and pituitary.
  • functions in controlling the endocrine system via secretion of neurohormones such as growth hormone-releasing hormone (GHRH) and thyrotropin-releasing hormone (TRH).
  • it also functions in controlling body temperature, hunger and thirst
61
Q

pituitary gland

A
  • the link between the nervous system and the endocrine system
  • it releases many hormones including: growth hormone (GH) and thyroid-stimulating hormone (TSH).
62
Q

parkinsons disease: cause

A

death of specific neurons deep within the brain.

the reasons for the death of these neurons is unknown but thought to be caused by exposure to pesticides.

63
Q

parkinsons disease: symptoms

A

shaking and trembling of the hands, arms and legs during movement, a stiff and rigid body and fixed stare.

64
Q

parkinsons disease: treatment

A

physiotherapy, exercise and a drug called levodopa

65
Q

the spinal cord

A
  • a bundle of nerve fibres enclosed within the spine, covered in specialised membranes called meninges and bathed in cerbrospinal fluid.
  • it carries messages to and from the brain.
  • it has 31 pairs of spinal nerves.
  • there are structures called the dorsal root, dorsal root ganglion and a ventral root associated with each spinal nerve.
  • the dorsal root carries sensory neurons
  • the dorsal root ganglion contains the cell bodies of those sensory neurons.
  • the ventral root carries the motor neurons.
  • spinal cord is composed of white matter and grey matter. outer region = white. inner = grey.
  • there is a central canal filled with cerebrospinal fluid.
66
Q

reflex action

A

involuntary responses to a stimulus.

  • carried out by reflex arcs.
  • reflex arcs consist of a sensory neuron, an interneuron and a motor neuron.
  • a common reflex action is the withdrawal reflex - touch something hot = pull hand away.
  • the sensory neuron detects that something hot has been touched and sends a message to the spinal cord via the dorsal root.
  • the sensory neuron synapses with an interneuron just inside the grey matter of the spinal cord and passes the message on.
  • the interneuron relays the message onto the motor neuron, whose cell body is just inside the grey matter of the spinal cord.
  • the motor neuron sends a message out through the ventral root to the skeletal muscles of the arm to pull the hand away from the hot object.
67
Q

nervous system vs endocrine system: NERVOUS

A 
speed of response: fast
messages carried by: electrochemicals (ion movement)
speed of transmission of message: fast
length of response: short-lived
areas affected: specific areas
68
Q

nervous system vs endocrine system: ENDOCRINE

A 
speed of response: slow
messages carried by: chemical hormones
speed of transmission of message: slow
length of response: long-lived
areas affected: wide areas
69
Q

Ganglion

A

A group of cell bodies located outside the central nervous system

70
Q

Threshold

A

The minimum stimulus needed to cause an impulse to be carried in a neuron

71
Q

All or nothing law

A

States that if the threshold is reached an impulse is carried, but if the threshold is not reached no impulse is carried

72
Q

Refractory period

A

A short time span after a neuron has carried an impulse during which a stimulus fails to cause a response

73
Q

Synaptic cleft

A

A tiny gap between the two neurons at a synapse

74
Q

Reflex arc

A

The pathway taken by a nerve Impulse in a reflex action

Biology (38 decks)

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