Chapter 4 - Divisions Of The Nervous System

Question 1

What are the two main divisions of the nervous system?

Answer 1

• central nervous system

- peripheral nervous system

Question 2

What does the central nervous system consist of?

Answer 2

• brain

- spinal cord

Question 3

What does the peripheral nervous system consist of?

Answer 3

• nerves that connect the CNS with glands, muscles and receptors
• 12 pairs of cranial nerves that arise from the brain
• 31 pairs of spinal nerves that arise from the spinal cord

Question 4

What are mixed nerves?

Answer 4

Nerves that carry impulses in both directions, ie. towards the brain/spinal cord and away from the brain/spinal cord

Question 5

How many nerves are mixed nerves?

Answer 5

• most cranial nerves

- all spinal nerves

Question 6

How are nerves connected to the spinal cord?

Answer 6

• connected by two roots: the ventral root and the dorsal root

Question 7

What does the ventral root contain?

Answer 7

• the axons of motor neurons that have their cell bodies in the grey matter of the spinal cord

Question 8

What do dorsal roots contain?

Answer 8

• axons of sensory neurons that have their cell bodies in a small swelling on the dorsal root called the dorsal root ganglion

Question 9

What are the divisions of the peripheral nervous system?

Answer 9

• afferent: somatic sensory neurons and visceral sensory neurons
• efferent: somatic, autonomic: sympathetic, parasympathetic

Question 10

Nervous vs hormonal coordination: nature of message

Answer 10

• electrical impulses and neurotransmitters

- hormones

Question 11

Nervous vs hormonal coordination: transport of message

Answer 11

• along the membrane of neurons

- by the bloodstream

Question 12

Nervous vs hormonal coordination: cells affected

Answer 12

• muscles and glands, other neurons

- all body cells

Question 13

Nervous vs hormonal coordination: type of response

Answer 13

• usually local and specific

- may be very general and widespread

Question 14

Nervous vs hormonal coordination: time taken to respond

Answer 14

• rapid: within milliseconds

- slower: from seconds to days

Question 15

Nervous vs hormonal coordination: duration of response

Answer 15

• brief: stops quickly when stimulus stops

- longer lasting: may continue long after the stimulus has stopped

Question 16

What are the similarities between hormonal and nervous coordination?

Answer 16

• some substances function as both hormones and neurotransmitters, eg, ADH, noradrenaline and dopamine.
• some substances such as oxytocin and adrenaline are secreted by neurons into extracellular fluid
• some hormones and neurotransmitters have the same effect on the same target cells. Eg, noradrenaline and the hormone glucagon bit act on liver cells to cause glycogen to be broken glucose

Question 17

What is a fight-or-flight response?

Answer 17

• a response that occurs when the body is in situations that involve stress, fear, anger, danger or competition.
• these responses prepare the body for increased activity

Question 18

What division of the nervous system is activated in a figh-or-flight response?

Answer 18

Sympathetic

Question 19

What physical changes occur in a fight-or-flight response?

Answer 19

• rate and force of contraction of the heart increases, consequently increasing blood pressure
• airways in the lungs dilate and the rate and depth of breathing increases
• secretion from sweat glands increases
• blood vessels in the organs involved in strenuous activity (skeletal muscles, heart and liver) dilate
• blood vessels in the organs not involved in strenuous activity (m stomach, intestines and skin) constrict
• blood glucose levels rise because the liver converts glycogen into glucose
• the Adrenal medullae release adrenaline and noradrenaline which intensify and prolong the above responses.

Question 20

What is the difference between the sympathetic and parasympathetic divisions?

Answer 20

Impulses form the sympathetic and parasympathetic divisions have differing effects on organs or tissues

Question 21

What does the sympathetic division do?

Answer 21

• produces response that tend to prepare the body for strenuous physical activity

Question 22

What does the parasympathetic division do?

Answer 22

• produced responses that generally maintain the body during relatively quiet conditions

Question 23

What neurotransmitters do the division release?

Answer 23

• sympathetic: noradrenaline

- parasympathetic: acetylcholine

Question 24

Effects of sympathetic vs parasympathetic stimulation: heart

Answer 24

• increases rate and strength of contraction

- decreases rate and strength of contraction

Question 25

Effects of sympathetic vs parasympathetic stimulation: lungs

Answer 25

- dilates bronchioles | - constructs bronchioles

Question 26

Effects of sympathetic vs parasympathetic stimulation: stomach, intestines

Answer 26

- decreases movement | - increases movement

Question 27

Effects of sympathetic vs parasympathetic stimulation: liver

Answer 27

- increases breakdown of glycogen into glucose | - increases uptake of glucose and synthesis of glycogen

Question 28

Effects of sympathetic vs parasympathetic stimulation: Iris of the eye

Answer 28

- dilates pupil | - constructs pupil

Question 29

Effects of sympathetic vs parasympathetic stimulation: sweat glands

Answer 29

- increases sweat secretion | - decreases sweat secretion

Question 30

What is the autonomic nervous system responsible for?

Answer 30

- the control of the body's internal environment | - operates without conscious control

Question 31

What regulates the autonomic nervous system?

Answer 31

- medulla oblongata - hypothalamus - cerebral cortex

Question 32

What is a ganglion?

Answer 32

- a groups of nerve cell bodies outside the CNS | - most nerve cell bodies are found in the grey matter of the CNS, but in the PNS they are found in ganglia

Question 33

Autonomic vs. somatic division: effectors

Answer 33

- heart muscle, involuntary muscles, glands | - skeletal muscle

Question 34

Autonomic vs. somatic division: general function

Answer 34

- adjustment of the internal environment (homeostasis) | - response to the external environment

Question 35

Autonomic vs. somatic division: efferent pathway

Answer 35

- two nerve fibres from CNS to effector with synapse in a ganglion - one nerve fibre fro CNS to effector, no synapse, no ganglion

Question 36

Autonomic vs. somatic division: neurotransmitter at effector

Answer 36

- noradrenaline or acetylcholine | - acetylcholine

Question 37

Autonomic vs. somatic division: control

Answer 37

- usually involuntary | - usually voluntary

Question 38

Autonomic vs. somatic division: nerves to target organ

Answer 38

- two sets: sympathetic and parasympathetic | - one set

Question 39

Autonomic vs. somatic division: effect on target organ

Answer 39

- excitation or inhibition | - always excitation

Question 40

What is the function of the afferent division?

Answer 40

Carries impulses into the CNS from receptors

Question 41

What is the function of the efferent division?

Answer 41

Carries impulses away from the CNS

Question 42

What are the divisions of afferent?

Answer 42

- somatic sensory neurons from skin and muscle | - visceral sensory neurons from internal organs