Ch. 12 Nervous Tissue Flashcards


Set Details Share
created 10 years ago by Tassimcc
766 views
updated 10 years ago by Tassimcc
show moreless
Page to share:
Embed this setcancel
COPY
code changes based on your size selection
Size:
X
Show:
1

nervous system

detects environmental changes that impact the body, then works together with the endocrine system to respond. It is responsible for all our behaviors, memories, and movement.

2

the excitable characteristic of nervous tissue

It is able to accomplish for all our behaviors, memories, and movement which allows for the generation of nerve impulses (action potentials)

3

3 fundamental steps in the nervous system

sensory
interpretation
motor response

4

Neuron

Receive, process and transmit information by manipulating the flow of charge across their membranes.

5

Neuron

the “functional unit” of the nervous system, they form complex processing networks within the brain and spinal cord.

6

Neuroglia

- do not generate or conduct nerve impulses.
- (glial cells) play a major role in support and maintain nutrition of the brain, but they do not manipulate information. They maintain the internal environment
•Forming the Blood Brain Barrier (BBB)
•Forming the myelin sheath (nerve insulation) around neuronal axons
•Making the CSF that circulates around the brain and spinal cord
•Participating in phagocytosis

7

4 types of neuroglia in the CNS:

1) Astrocytes
2) Oligodendrocytes
3) Microglia
4) Ependymal cells

8

Ependymal cells

- form and circulate CSF

9

Astrocytes

- support neurons in the CNS
•Maintain the chemical environment (Ca2+ & K+)

10

Microglia

- participate in phagocytosis

11

Oligodendrocytes

- produce myelin in CNS

12

2 types of neuroglia in the PNS:

1) Satellite cells
2) Schwann cells

13

Satellite cells

- support neurons in PNS

14

Schwann cells

- produce myelin in PNS

15

Myelination

the process of forming a myelin sheath which insulates and increases nerve impulse speed.
It is formed by Oligodendrocytes in the CNS and by Schwann cells in the PNS.

16

Demyelination

refers to the loss or destruction of myelin sheaths around axons. It may result from disease, or from medical treatments such as radiation therapy and chemotherapy.

17

Regeneration tube

When an axon is injured, the neurolemma aids regeneration by forming a ________ ______ that guides and stimulates regrowth of the axon.

18

Neurolemma

The outer nucleated cytoplasmic layer of the Schwann cell, which encloses the myelin sheath (sheath of Schwann).

19

Regeneration

The cell bodies of neurons can only be repaired through _____ after an injury.

20

Nodes of Ranvier

- are the gaps in the myelin sheath.
 Each Schwann cell wraps one axon segment between two nodes of Ranvier.

21

Divisions of the Nervous System

Includes; the central nervous system (CNS) and The peripheral nervous system (PNS)

22

Central Nervous System (CNS)

- consists of the brain and spinal cord.
- Most signals that stimulate muscles to contract and glands to secrete

23

Peripheral Nervous System (PNS)

- consists of all nervous tissue outside the CNS, including nerves, ganglia, enteric plexuses, and sensory receptors.
- divided into:
1) A somatic nervous system (SNS)
2) An autonomic nervous system (ANS)
3) An enteric nervous system (ENS)

24

Somatic Nervous System (SNS)

consists of:
- Somatic sensory
- Somatic motor

25

Somatic sensory

(afferent) neurons that convey information from sensory receptors.

26

Sensory or afferent neurons

convey APs into the CNS through cranial or spinal nerves. Most are unipolar.

27

Motor or efferent neurons

convey APs away from the CNS to effectors (muscles and glands) in the periphery through cranial or spinal nerves. Most are multipolar.

28

Interneurons or association neurons

mainly located within the CNS between sensory and motor neurons. They integrate (process) incoming sensory information from sensory neurons and then elicit a motor response by activating the appropriate motor neurons. Most interneurons are multipolar in structure.

29

Somatic motor

(efferent) neurons that conduct impulses away from the CNS towards the skeletal muscles.

30

Autonomic Nervous System (ANS)

consists of:
1. Sensory neurons that convey information from autonomic sensory receptors located primarily in visceral organs.
2. Motor neurons under involuntary control conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands.
•the sympathetic division
•the parasympathetic division

31

Enteric Nervous System (ENS)

the “brain of the gut”, involuntarily controls GI propulsion, and acid and hormonal secretions.

32

Ganglia

are small masses of neuronal cell bodies located outside the brain and spinal cord, usually closely associated with cranial and spinal nerves.

33

Parts of the neuron

1) A cell body
2) An axon
3) Dendrites
4) Axon terminals

34

Dendrites

- (little trees) are the receiving end of the neuron.
- short, highly branched structures that conduct impulses toward the cell body.
- They also contain organelles.

35

Cell body

- nucleus surrounded by cytoplasm.
- neurons contain organelles such as lysosomes, mitochondria, Golgi complexes, and rough
ER for protein production (in neurons, RER is called Nissl bodies) .

36

Axons

- conduct impulses away from the cell body toward another neuron or effector cell.
- Contains Axon hillock, initial segment, and trigger zone.

37

Axon terminals

The axon and its collaterals end by dividing into many fine processes

38

Synaptic end bulbs

The tips of some axon terminals swell into
bulb-shaped structures

39

Synapse

The site of communication between two neurons or
between a neuron and another effector cell

40

Synaptic cleft

the gap between the pre and post-synaptic cells.

41

Synaptic vesicles

Synaptic end bulbs on the axon terminals of presynaptic neurons contain many tiny membrane-enclosed sacs that store packets of neurotransmitter chemicals.

42

Electrical impulses or action potentials (AP)

cannot propagate across a synaptic cleft. Instead, neurotransmitters are used to communicate at the synapse, and re-establish the AP in the postsynaptic cell.

43

Slow axonal transport

supplies new axoplasm (the cytoplasm in axons)

44

Fast axonal transport

occurs in an anterograde (forward) and a retrograde (backward)

45

Anterograde (forward)

direction moves organelles and synaptic vesicles from the cell body to the axon terminals.

46

Retrograde (backward)

direction moves membrane vesicles and other cellular materials from the axon terminals to the cell body to be degraded or recycled.

47

Multipolar neurons

have several dendrites and only one axon and are located throughout the brain and spinal cord. The vast majority of the neurons in the human body.

48

Bipolar neurons

have one main dendrite and one axon.They are used to convey the special senses of sight, smell, hearing and balance. As such, they are found in the retina of the eye, the inner ear, and the olfactory area of the brain.

49

Unipolar (pseudounipolar) neurons

contain one process which extends from the body and divides into a central branch that functions as an axon and as a dendritic root and often employed for sensory neurons.

50

Structural classification

based on the number of processes (axons or dendrites) extending from the cell body.

51

Functional classification

based on electrophysiological properties (excitatory or inhibitory) and the direction in which the AP runs.

52

White matter

_____ _______of the brain and spinal cord is formed from aggregations of myelinated axons from many neurons. The lipid part of myelin imparts the white appearance.

53

Gray matter

(gray because it lacks myelin) of the brain and spinal cord is formed from neuronal cell bodies and dendrites.