Nervous System

Question 1

Nervous System is divided into:

Answer 1

• Central NS

- Peripheral NS

Question 2

Define Central Nervous System (CNS)

Answer 2

Body’s coordinating center for mechanical and chemical actions

• made up of brain and spinal cord

Question 3

Define Peripheral Nervous System (PNS)

Answer 3

• All parts of NS that relay info between CNS and other parts of the body
• Divided into somatic voluntary and autonomic involuntary

Question 4

PNS consists of:

Answer 4

• Nerves
• Ganglia
• Sensory Receptors
• Effector Organs (muscles and glands)

Question 5

Define Somatic NS

Answer 5

• Voluntary control (except reflex arc)
• Bring info from external environment to CNS and send info back to skeletal muscle
• send nerves to skeletal muscle,bones n skin
• meditates bodily movement
• composed of 12 pairs of cranial nerves (in brain) and 31 pairs of spinal nerves
• only sensory neurons, motor, or both

Question 6

Define Autonomic NS

Answer 6

• Involuntary control
• controls organs
• bring info from internal environment to CNS and carries signals back to regulate internal environment
• Controls smooth and cardiac muscle, internal organs and glands
• Motor neurons (pre-ganglia and post-ganglia) stimulate target effectors (muscles,organs)
• Subdivided into : Sympathetic NS and parasympathetic NS

Question 7

Two types of Nerve cells in NS

Answer 7

• Glial Cell

- Neurons

Question 8

Define glial cell

Answer 8

• non conducting
• structural support
• metabolism of nerve cells

Question 9

Define Neurons

Answer 9

• Nerve cells that conduct nerve impulses

- functional units of NS

Question 10

3 types of Neurons

Answer 10

• Sensory neurons
• Motor neurons
• Interneurons

Question 11

Define sensory neurons

Answer 11

• Carry impulses (stimuli) from sensory receptors to CNS
• aka afferent (towards) neurons
• Ganglia: collection of sensory nerve cell bodies

Question 12

Define Ganglia

Answer 12

collections of sensory nerve cell bodies (part of sensory neurons)

Question 13

Motor neurons

Answer 13

• Carry impulses from CNS to effectors (cell to organ that responds to stimulus)
• aka efferent (away) neurons

Question 14

Interneurons

Answer 14

• Found in brain and spinal cord
• Link sensory neurons to motor neurons
• Integrate and interpret sensory info and connect to outgoing motor neurons

Question 15

Dendrites

Answer 15

Projections of cytoplasm that carry impulses towards cell body

Question 16

Cell bodies

Answer 16

• Contain nucleus

- Receive info from dendrites

Question 17

Axon

Answer 17

Extension of cytoplasm that carries nerve impulses away from cell body

Question 18

Myelin Sheath

Answer 18

Insulated covering over axon of nerve cell

Question 19

Schwann Cell

Answer 19

Special type of glial cell that produces the myelin sheath

Question 20

Nodes of Ranvier

Answer 20

• Reoccuring gaps between sections of myelin sheath along axon
• Nerve impulses jump from node to node
• Speeds up nerve transmission

Question 21

Neurilemma

Answer 21

• Delicate membrane surrounding axons within PNS ONLY
• formed by schwann cells
• promotes regeneration of damaged axons
• not all myelinated cells contain neurilemma

Question 22

What is the speed of an impulse dependent on?

Answer 22

• Myelin

- Diameter of axon: Bigger = faster

Question 23

Myelin

Answer 23

Myelinated axon send impulses faster than non-myelinated axons bcs impulse jumps from node to node along axon

Question 24

White Matter

Answer 24

Nerves within brain that contain myelinated fibres

• called white matter bcs myelinated axons are whitish in appearance

Question 25

Grey matter

Answer 25

- Other nerve cells in brain and spinal cord, lack myelin sheath

Question 26

Grey and white matter

Answer 26

Cells of grey and white matter in CNS lack neurilemmas, causing damages to CNS to be permanent.

Question 27

Define Reflex Arc

Answer 27

- simplest nerve pathway - neural circuit thru spinal cord - reflexes involuntary & unconscious (no brain coordination)

Question 28

Essential components for reflex arc

Answer 28

1. Receptor 2. Sensory neuron 3. Interneuron (in spinal cord) 4. Motor neuron 5. Effector

Question 29

Sympathetic NS

Answer 29

- Prepares body for stress | - Nerves come from ribs and small of back

Question 30

Parasympathetic NS

Answer 30

- reverse effect of sympathetic NS and restores body to normal - Nerves exit from brain,neck, or tailbone - Contains Vagus Nerve: branches of nerve supply nerves to the heart, bronchi of lungs, liver, pancreas, and digestive tract

Question 31

Flight or Fight

Answer 31

- Sympathetic NS activated > stress response > u escape, fight or flight - requires intense muscular effort