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Biology 30 > Nervous System: Chapter 21-24 > Flashcards

Nervous System: Chapter 21-24 Flashcards

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1
Q

Nervous system

A

In animals, system made up of cells and organs that let an animal detect changes and respond to them, made up of the brain and spinal, as well as the nerves that emerge from them and connect them to the rest of the body.
- Has two major divisions: the central nervous system, and the peripheral nervous system.

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2
Q

Central nervous system

A

Network of nerves that includes the brain and spinal cord; integrates and processes information sent by nerves.

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3
Q

Peripheral nervous system

A

Network of nerves that carry sensory messages to the central nervous system (CNS) and send information from the CNS to the muscles and glands; consists of the autonomic and somatic system.

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4
Q

Autonomic system

A

In vertebrates, the division of peripheral nervous system that is under involuntary control; regulates glandular secretions and the function of smooth and cardiac muscle. Consists of the sympathetic and parasympathetic nervous system.

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5
Q

Sympathetic nervous system

A

Division of the autonomic system that regulates involuntary processes in the body; works in opposition to the parasympathetic nervous system. Activated in stress related situations.

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6
Q

Parasympathetic nervous system

A

Division of the autonomic system that regulates involuntary processes in the body; works in opposition with the sympathetic nervous system. Activated when the body is calm and at rest.

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7
Q

Somatic system

A

In vertebrates, division of peripheral nervous system that controls voluntary movement of skeletal muscle; conducts signals from the central nervous system to the skeletal muscles and signals from the sensory receptors in the body to the central nervous system.

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8
Q

Neurons

A

Basic structural and functional units of the nervous system.

  • Nerve-impulse conducting cells
  • Consists of a nucleus, cell body (soma), dendrites, axons, branching ends and a myelin sheath. (Four common features are dendrites, a cell body (soma), an axon, and branching ends.)
  • Function is to respond to physical and chemical stimuli, to conduct electrochemical signals, and to release chemicals that regulate various body processes.
  • Activity of neurons is supported by glial cells.
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9
Q

Glial cells

A

Support cell of the nervous system that nourishes neurons, removes their wastes, defends against infection, and provides a supportive framework for all the nervous system tissue.

  • Outnumber neutrons 10 to 1.
  • Accounts for half the nervous system.
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10
Q

Dendrites

A

Short, branching terminals on a neuron that receives signals from other neurons or sensory receptors and relays the impulse to the cell body.
Very numerous and highly branched to increase surface area.

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11
Q

Cell body

A

Main part of neuron containing nucleus and organelles and is the site of the cell’s metabolic reactions.
- Processes input from dendrites. If the input is large enough, it relays the input to the axon, where an impulse is initiated.

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12
Q

Axon

A

Long, cylindrical extension of a neuron’s cell body that can range from 1mm to 1m in length.

  • Transmits impulses away from the cell body along its length to the next neuron.
  • Terminal end of an axon branches into many fibres.
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13
Q

Myelin sheath

A

The fatty, insulating layer around the axon of a neuron, composed of Schwann cells.

  • Protects myelinated neurons and speeds the rate of nerve impulse transmission.
  • Gives axons a glistening white appearance.
  • Axons with the myelin sheath are said to be myelinated, those without are unmyelinated.
  • Created by Schwann cells.
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14
Q

Schwann cells

A

A type of insulating glial cell that wraps around the axon of a neuron, creating a myelin sheath.

  • Myelinated neurons form white matter, where unmyelinated neurons form grey matter.
  • Most neurons in the peripheral nervous system are myelinated.
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15
Q

Basic impulse transmission pathway

A

Sensory input, integration, motor output.

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16
Q

Sensory neurons

A

Sensory neurons gather information from the sensory receptors (senses) and transmit these impulses to the central nervous system (brain and spinal cord).

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17
Q

Interneurons

A

Are found in the brain and spinal cord; acts as an integration centre. (In the CNS, a link between sensory and motor neurons)

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18
Q

Motor output

A

Motor neurons transmit information from the central nervous system to the muscles, glands, and other organs (effectors).

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19
Q

Effectors

A

Muscles, glands, and other organs that respond to impulses from the motor neurons.

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20
Q

Reflexes

A

Sudden, unlearned, involuntary responses to certain stimuli. Some neurons are organized to enable your body to react rapidly in times of danger, even before you are consciously aware of the threat.

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21
Q

Reflex arc

A

Simple connection of neurons that results in a reflex action in response to a stimulus.

  • Uses very few neurons to transmit messages, which causes reflexes to be very active. (As little as 50 milliseconds.) Ex. Withdrawal reflexes only use three neurons.
  • Reflex arc moves directly to and from the brain or spinal cord, before the brain centres involved with involuntary control have time to process the sensory information.
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22
Q

How do neurons send messages?

A

Electrochemically.

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23
Q

Membrane potential

A

The charge separation across the membrane is a form of potential energy.

  • In a resting neuron, the cytoplasmic side of the membrane is negative, relative to the extracellular side. The semi-permeable membrane blocks ions, because the concentrations always try to balance out (osmosis).
  • Potassium (K+ ions) pass through ion channels easily, while chlorine (Cl-) and sodium (Na+) ions have difficulty passing.
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24
Q

Resting membrane potential

A

The potential difference across the membrane in a resting neuron (No nerve impulses are being transmitted along the axon.)

  • Resting membrane potential of most unstimulated neurons is -70mV (millivolts) meaning that the inside of the neuron is 70 mV less than the outside.
  • Negative on the inside, relative to the outside.
  • Provides energy for the generation of a nerve impulse in response to an appropriate stimulus.
  • The energy for any eventual impulses is stored in the electrochemical gradient across the membrane.
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25
Q

Polarization

A

The process of generating a resting membrane potential of -70mV.

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26
Q

Sodium-potassium exchange pump

A

Uses energy of ATP to transfer 3 sodium ions out for every 2 potassium ions that go in.

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27
Q

Action potential

A

When a neuron sends information down an axon, away from the cell body. (aka spike or impulse)

  • Occurs at nodes of Ranvier in myelinated neurons because the myelin sheath insulates the axonal membrane that it encircles. When the membrane at the node of Ranvier becomes depolarized to -55mV, action potential occurs.
  • Action potential only occurs between -55mV or any other amount up to 0.
  • Neuronal membrane is depolarized if the transmembrane potential is reduced to less than the resting potential of -70mV.
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28
Q

Threshold potential

A

The potential difference of -55mV.
When transmembrane potential at a node of Ranvier reaches threshold, special structures in the membrane called voltage-gated sodium channels open and make the membrane permeable to sodium ions. Sodium ions rush into axon, making a region of the axon +35mV.
- In response to this change, sodium channels close and voltage-gated potassium channels open. Potassium ions move out of axon carry positive charge out of the neuron. The membrane is repolarized.
- Membrane potential even overshoots, about -90mV. Potassium channels close, sodium-potassium pump brings back the normal resting potential of -70mV. This brief period of time is the refractory period.

29
Q

Repolarized

A

Return of nerve to its resting potential.

30
Q

Refractory period

A

Brief time (a couple of milliseconds) between triggering an impulse along an axon and an axon’s readiness for next impulse; axons cannot transmit another impulse in this time.

31
Q

Speed difference of a nerve impulse in myelinated vs unmyelinated neuron

A

In unmyelinated neurons, action potentials can occur at all locations along a membrane. Therefore, they can occur one beside the other. Transmission of impulse along an unmyelinated axon is much slower than a myelinated axon.

32
Q

Synapse

A

Junction between two neurons or between a neuron and an effector (muscle or gland).

33
Q

Neuromuscular junction

A

Synapse between a motor neuron and a muscle cell.

  • Impulse travels length of axon until it reaches the far end, or synaptic terminal.
  • Most neurons are not connected, but have a gap called the synaptic cleft. Impulse cannot jump from one neuron to the other.
  • Neurotransmitters carry the neural signal from one neuron to the other, or from a neuron to an effector.
34
Q

Neurotransmitter

A

Chemical messenger secreted by neurons to carry a signal from one neuron to another, or from a neuron to an effector.

  • Neurotransmitters are released from presynaptic vesicles.
  • Diffuses across cleft and binds to receptors on postsynaptic side, opening Na channels.
  • Causes action potential in postsynaptic neuron.
  • Most common types are ACH (acetylcholine) and norepinephrine.
35
Q

Acetycholine (ACH)

A

Primary neurotransmitter of both somatic nervous system and parasympathetic nervous system.
- Crosses a neuromuscular junction, causing depolarization and contraction of muscle fibre.

36
Q

Cholinterase

A

Enzyme that breaks down ACH allowing the ion channels to close and the membrane to repolarize.

37
Q

Excitatory synapse:

A

Occurs when neurotransmitter depolarize postsynaptic membrane; more likely for the postsynaptic membrane to have action potential.

38
Q

Inhibitory synapse

A

Occurs when neurotransmitter reduces ability of postsynaptic membrane to depolarize makin it less likely to have an action potential.

39
Q

White matter

A

Type of nervous tissue composing the CNS. Contains myelinated axons that run together in tracts. Forms the inner region of some areas of the brain, and outer area of spinal cord.

40
Q

Grey matter

A

Mostly cell bodies, dendrites, and short, unmyelinated axons (nerve fibres). Found in outside areas of the brain and forms H-shaped core of the spinal cord.

41
Q

Spinal cord

A

Column of nerve tissue that extends from brain downward through a canal within the backbone.

  • For connection between brain and peripheral nervous system.
  • Sensory nerves carry message from the body to brain for interpretation. Motor nerves relay messages from the brain to the effectors.
  • Primary reflex centre.
  • Tissues of spinal cord are protected by cerebrospinal fluid, soft tissue layers, spinal column and series of backbones (vertebrae).
42
Q

Brain

A

Maintains homeostasis, centre for intelligence, consciousness and emotion.

  • Three general regions: hindbrain, midbrain and forebrain.
  • Meninges enclose the brain and spinal cord.
43
Q

Meninges

A

Three layers of tough, elastic tissue within the skull and spinal column which directly enclose the brain and spinal cord. Prevents direct circulation of blood through the cells of the brain and spinal cord. Creates blood-brain barrier.

44
Q

Blood-brain barrier

A

Protective barrier formed by glial cells and blood vessels that separates the blood from the CNS; selectively controls the entrance of substances into the brain from the blood.

45
Q

Cerebellum

A

Controls coordinated muscular activity below the level of consciousness. (Posture, reflexes, body movements, fine motor skills such as writing.) Receives info from proprioceptors, located within skeletal muscles and joints.

46
Q

Medulla oblongata

A

Responsible for involuntary responses (heart rate, dilation of blood vessels/blood pressure, rate and depth of breathing).

47
Q

Pons

A

Relay between the cerebellum and the cerebral cortex.

48
Q

Midbrain

A

Relays visual and auditory information between areas of hindbrain and forebrain. Important for eye movement and control of skeletal muscles.

49
Q

Thalamus

A

Central relay system for sensory impulses, channels sensory impulses to appropriate regions. All the regions of the cerebral cortex communicates with the thalamus.

50
Q

Hypotalamus

A

Regulates body temperature, control of hunger, production of hormones, regulation of water and electrolyte balance, controls certain aspects of behaviour.

51
Q

Cerebrum

A

Divided into two hemispheres, right and left. Has 4 different lobes. Contains centres for memory, consciousness, language, and interprets and controls the response to sensory information.

52
Q

Cerebral cortex

A

Thin outer covering of grey matter that covers each cerebral hemisphere of the brain; responsible for language, memory, personality, conscious thought, and other activities associated with thinking and feeling. Consists of 4 lobes.

53
Q

Corpus callous

A

White matter that connect cerebral hemispheres. Sends messages between the two hemispheres.

  • Right brain is associated with holistic and intuitive thinking, artistic abilities.
  • Left brain is associated with logical ways of thinking, linguistics and math skills.
54
Q

Occipital lobe

A

Responsible for vision (receiving and analyzing), recognizes what is being seen. Damage can result in person able to see objects, but not recognize them.

55
Q

Temporal lobe

A

Responsible for hearing and auditory reception. Contains Wernicke’s area, which stores information involved with language comprehension.

56
Q

Parietal lobes

A

Receives and processes sensory information from the sense of touch, pressure, pain, and taste.

57
Q

Frontal lobes

A

Associated with motor areas, controls voluntary skeletal movement. Contains Broca’s area, which coordinates muscles for speech and translates thoughts into speech. Also is associated with conscious thought, intelligence, memory and personality.

58
Q

Broca’s area

A

Coordinates muscles for speaking and translates thought into speech. Damage results in inability to speak.

59
Q

Wernicke’s area

A

Stores info involved with language comprehension.

60
Q

Sensory adaptation

A

The filtering by the brain of redundant, insignificant sensory information.
When a receptor becomes accustomed to a stimulus and ceases to fire, even though the stimulus is still present.

61
Q

Sensory receptors

A

Nerve endings and cells that detect sensory information. Stimulated by external stimuli and in return, stimulate sensory neurons which send messages to the brain for interpretation.
- Grouped by the kind of stimulus they receive.

62
Q

Sensation

A

Occurs when the neural impulses arrive at the cerebral cortex. Ex. Face detects the warmth of a beam of sunlight. When the brain receives and processes this info, you will feel a sensation of warmth on your cheek.

63
Q

Photoreceptor

A

Respond to visible wavelength of light.

64
Q

Mechanoreceptor

A

Sensitive to mechanical energy

65
Q

Thermoreceptor

A

Sensitive to heat and cold.

66
Q

Osmoreceptor

A

Detect changes in the concentration of solutes in body fluids.

67
Q

Chemoreceptor:

A

Sensitive to specific chemicals such as the concentration of oxygen in the blood.

68
Q

Nocireceptor

A

Pain receptor that is sensitive to tissue damage.

Biology 30 (7 decks)

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