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Flashcards in The Nervous System Deck (28)
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1

Central Nervous System

- made up of the brain, spinal cord, and the retina of the eye
- protected by the skull, meninges (layers of tissue), and cerebral spinal fluid
- 31 segments of the spinal cord, a pair of spinal nerves extends from each segment into the body

2

Peripheral Nervous System

- 43 pairs of nerves which connect the body to the CNS
- made up of sensory neurons, which receive stimuli, and motor neurons, which respond to stimuli
- broken down into somatic and autonomic nervous systems

3

Somatic Nervous System

- voluntary, controlled consciously; e.g. movement of muscles
- communicates with sense organs and voluntary muscles
- broken down into sensory (afferent) and motor (efferent) nervous systems

4

Sensory Nervous System

- afferent
- sensory input

5

Motor Nervous System

- efferent
- motor output

6

Autonomic Nervous System

- involuntary, controls unconscious impulses; e.g. heart beat
- communicates with internal organs and glands
- broken down into the sympathetic and parasympathetic nervous systems

7

Sympathetic Nervous System

- arousing
- speeds up heart rate and breathing, raises blood pressure, stops digestive activity

8

Parasympathetic Nervous System

- calming
- slows down heart rate and breathing, lowers blood pressure, resumes digestive activity

9

Reflex

- rapid, unlearned, involuntary response to a stimulus, e.g. sneezing, coughing, blinking, ducking, dilation of pupils
- protect people from injury or deal with things that require immediate attention

10

Receptors (reflex)

- located in skin or sense organs
- detect stimulus, create impulse

11

Sensory neuron (reflex)

- conducts nerve impulses towards the CNS
- carries messages from a receptor to the spinal cord, this is called the afferent pathway

12

Interneuron (reflex)

- connect sensory and motor neurons
- carry messages from sensory to motor neurons
- transmit signals up the spinal cord to the brain, where they are perceived as pain

13

Motor neurons (reflex)

- conduct nerve impulses from the CNS to an effector
- carries messages from the spinal cord to an effector, called the efferent pathway

14

Effector (reflex)

- responds to impulses by contracting (if a muscle fibre) or secreting enzymes or hormones (if a gland)

15

Neuron

- functional cell of the nervous system
- sends and receives nerve impulses
- 100 billion on the brain's surface
- 10% of cells in brain

16

Dendrites

- short
- receive nerve impulses

17

Axon

- long
- send nerve impulses away from the cell body

18

Myelin sheath

- Schwann cells (fatty tissue) that wraps around axons, enabling impulses to be sent quickly

19

Cell body

- dendrites and the axon are connected to the cell body
- contains nucleus

20

Axon terminal

- end of axon
- stores vesicles which contain neurotransmitters

21

Nodes of Ranvier

- gaps in myelin sheath

22

Synapses

- small gap present between the end of an axon on one neuron and the dendrite or cell body of another neuron
- where neurotransmitters diffuse

23

Action potential

1. Stimulus causes change in permeability
2. Na voltage gated channels open, Na ions diffuse into neuron, beginning action potential
3. Interior of cell is now positively charged, exterior negatively charged
4. Na channels close, K channels open
5. K ions diffuse outside of cell, reversing charges again, and signalling the end of action potential
6. Na and K ions are pumped through sodium potassium pump to return to resting potential (Na goes out, K goes in)

24

Neurotransmitters

- vesicles containing neurotransmitters fuse with the presynaptic membrane when action potential reaches the axon terminal
- fusion releases neurotransmitter molecules into synaptic cleft
- molecules diffuse across the synaptic cleft, bind with receptor molecules in the post-synaptic cleft
- this changes permeability of the post-synaptic membrane/opens ion channels

25

Forebrain

- functions include receiving and processing information, thinking, perceiving, producing and understanding language, and controlling motor function
- most of the actual information processing in the brain takes place in the cerebral cortex

26

Midbrain

- involved in auditory and visual responses as well as motor function

27

Hindbrain

- assists in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information
- contains the medulla oblongata, responsible for controlling autonomic functions (breathing, heart rate, digestion, etc.)
- oldest and most basic part of the brain

28

Limbic System

emotional control centre of the brain