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Human Biology > Nervous System > Flashcards

Nervous System Flashcards

1
Q

What is a neuron?

A

Specialised cell with cell bodies containing a nucleus and long extentions or fibers that transmit signals.

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2
Q

Basic parts of the neuron

A

A cell body and cell extensions called dendrites and axons

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3
Q

What is the cell body

A

The region of the neuron around the nucleus that is responsible for producing substances that are necessary for the nerve cell to live and carry out its functions

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4
Q

What is an axon?

A

A single long cell extension that often makes distant connections.
May give out branches which often split off and right angles and usually have a myelin covering.

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5
Q

What are nerves?

A

Bundles of neurons that give off message signals called nerve impulses

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6
Q

What is a dendrite?

A

A cell extension that is usually much smaller than an axon, has no myelin covering and is specialised to recieve impulses from sensory cells or from axons of other neurons.

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7
Q

What is the CNS

A

Central Nervous System - consisting of brain and spinal cord

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8
Q

What is PNS

A

Peripheral Nervous System - consisting of nerves that run to and from the CNS

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9
Q

Note on - Sensory Neurons

A

Receive information froma sensory receptor (special structures that detect changes in the environment).
Most have one long axon bringing messages from particular receptors
Cell bodies lie near the CNS

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10
Q

Note on - Interneurons

A

Located within the CNS - integrate incoming information with out going messages.
Usually have a highly branched system of dendrites able to receieve input from many different neurons at once
Axons may not be myelinated.

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11
Q

Note on - Motor Neurons

A

Transmit commands away from central nervous system to the muscles and glands.
One long axon, usually branched at the end, bringing messages to a muscle or gland

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12
Q

What are Neuroglial cells and what are CNS glial cells and PNS glial cells

A

-Companion cells that provide support, protectionand nutritional stability to the neuron.
-CNS glial cells - Microglia, Ependymal cells, Astrocytes, Oligodendrocytes
-PNS glial cells - Satellite cells, Schwann cells

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13
Q

Function of Microglia

A
  • monitor health and perform defence functions for neurons.
    -differentiate to become a type of macrophage to phagocytose debris and microorganisms
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14
Q

Function of Ependymal cells

A

-line the central cavities of the brain and spinal cord and help circulate cerebrospinal fluid.

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15
Q

Function of Astrocytes

A

-regulate the chemical environment around the neurons and exchanges between neurons and capillaries

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16
Q

Function of Oligodendrocytes

A

Wrap around neuron fibres, forming myelin sheath

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17
Q

Function of Satellite Cells

A

Multifunctional especially during disease.
Found surronding neuron cell bodies within ganglia

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18
Q

Function of Schwann Cells

A

Found wrapped around and insulating axons of sensory and motor neurons forming a myelin sheath.

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19
Q

What are the Nodes of Ranvier?

A

Uninsulated spots that occur at regular intervals on an axon.
-These nodes and mylein sheath create conditions that speed the nerve impulses as it is conducted along surface of axon

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20
Q

Functions of neurons:

A

To transmit info:
-From the environment to the spinal cord and brain
-From one cell to another within the CNS
-From brain and spinal cord to other parts of the body

Nerve cells transmit this infor in form of nerve impulses

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21
Q

When at rest, what is the charge of the cytoplasm and why?

A

Approx -65 millivolts
Means that the insde of the cell is negatively charged (greater conc of K+ inside axon) relative to extracellular fluid along the outside of the membrane (greater conc of Na+ outside an axon)

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22
Q

Which ions play a principle role in the development of electrical potential along the membrane of the neuron?

A

Sodium (Na+) and Potassium ions (K+)

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23
Q

Transmembrane protein embedded within cell membranes of neurons

A

Sodium-potassium pumps - uses the energy stored in molecules of ATP (active transport) to move K+ into the neuron at the same time as they move Na+ out of the neuron - maintain resting potential

24
Q

What is a stimulus

A

An internal or external environmental change taht excites a neuron

25
Q

What is an action potential?

A

A rapid change in polarity across the membrane of the neuron
-If the stimulus causes the axomembrane to depolarise to a certain level an action potential occurs.

26
Q

What happens at the 2 types of gated channel proteins required by the action potential

A

1) Sodium gates open : Na+ flows into cell. Membrane potential changes from -65mV to +40mV - depolarisation
2) Potassium gates open : K+ flows to outside axon. Membrane potenmt

27
Q

What is the purpose of a refractory period

A

It prevents the action potential from going backwards as the Na+ gates are unable to open

28
Q

What does the myelin sheath do?

A

It acts as an insulator. It prevents the transport of ions across the neuron membrane beneath it

29
Q

Where can the action potential be generated?

A

Only at the nodes of Ranvier where the gated channels are concentrated

30
Q

What is saltatory conduction?

A

A very fast form of nerve impulse conduction where the action potential jumps from one node to the next causing depolarisation only at these specific points

31
Q

What are effectors?

A

Muscles & glands - response occured when stimulated by nerves

32
Q

What is a synapse?

A

Where a neuron communicates with another neuron or an effector

33
Q

What is the synaptic cleft?

A

Minute gaps separate neurons and effectors at synapses

34
Q

How many neurotransmitters are there?

A

25

35
Q

What removes neurotransmitters from the synaptic cleft?

A

Enzymes

36
Q

What neurotransmitter is found at the neuromuscular junction?

A

Acetylcholine

37
Q

What enzyme works on acetylcholine

A

Acetylcholinesterase - broken down to acetic acid & choline

38
Q

What is membrane on the axon side of the synapse?

A

Presynaptic membrane

39
Q

How do neurotransmitters work?

A

Depolarisation reaches the presynaptic membrane - calcium rushes in - sudden rise in cytoplasmic Ca causes the release of neurotransmitters into synaptic vesicles - merge with membrane and released into the cleft - diffuse to the other side of the cleft - bind with receptor molecules in postsynaptic membrane and cause the opening of ion channels

40
Q

What is an excitatory synapse?

A

Neurotransmitters depolarised postsynaptic membrane - continuation of nerve impulse

41
Q

What is an inhibitory synapse?

A

Reduces the ability of the postsynaptic membrane to depolarise

42
Q

What is grey matter?

A

contains cell bodies and short
nonmyelinated nerve fibres

43
Q

What is white matter?

A

myelinated fibres that run in
bundles called tracts

44
Q

What is the somatic nervous system?

A

motor neurons that control voluntary responses

45
Q

What is the autonomic nervous system?

A

Motor neurons that carry messages about involuntary activities

46
Q

What are the parts of the brain?

A

The cerebrum, thalamus,
hypothalamus, cerebellum, and brain stem.

47
Q

What is the cerebrum?

A

-receives sensory information
-sends messages to move skeletal muscles
-integrates incoming and outgoing nerve impulses
-performs activities such as thinking, learning, & memory

48
Q

What is the thalamus?

A

Relays most sensory information from the spinal cord and
central parts of the brain to the cerebral cortex.
➢ Interprets certain sensory messages such as those of pain,
temperature, and pressure.

49
Q

What is the hypothalamus?

A

➢ Controls various homeostatic functions such as body
temperature, respiration, and heartbeat.
➢ Directs hormone secretions of the pituitary gland

50
Q

What is the cerebellum?

A

Coordinates subconscious movements
➢ Contributes to muscle tone, posture, and balance

51
Q

What is the brain stem?

A

-origin of many cranial nerves
-reflex centre for movements of eyeballs, head, and trunk
-regulates heartbeat and breathing
-plays a role in consciousness
-transmits impulses between brain and spinal cord.

52
Q

What is the spinal cord?

A

Extends from the brain stem down the back through the vertebral column
Tiny central canal filled with cerebrospinal fluid continuous with fluid-filled sacs in brain
fluid acts as a shock absorber, and brings nutrients, hormones and wbc to parts of the brain

53
Q

What are the 3 parts of the autonomic nervous system?

A

Sympathetic, parasympathetic, and enteric

54
Q

What does the enteric nervous system control?

A

Digestion system

55
Q

What does the parasympathetic control?

A

The ‘rest & digest’ response

Human Biology (17 decks)

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