3A The central and peripheral nervous systems

Question 1

Organisation of the human nervous system

Answer 1

Human nervous system
Divides into: Central nervous system (divides into brain and spinal cord) and Peripheral nervous system
|
V
Divides into: Autonomic nervous system (divides into sympathetic nervous system, parasympathetic nervous system and enteric nervous system) and Somatic nervous system

Question 2

What does the central nervous system do

Answer 2

• processes and coordinates all incoming (sensory) info and initiates outgoing (motor) messages to be sent to the body
• can be conscious or unconscious commands

Question 3

Brain

Answer 3

a complex structure that recieves and processes sensory stimuli from the body, coordinate responses, including voluntary movements, emotions and concious thought

• communicates with body via spinal cord and its nerves, as well as cranial nerves (one being vagus nerve) that connect the brain directly to various organs and muscles of the body

Question 4

Spinal cord

Answer 4

• carries sensory info from body to the brain for processing
• carries motor info from brain to body
• involved in involuntary responses e.g spinal reflex

Question 5

Spinal reflex + steps

Answer 5

an involuntary and unconscious response to a stimulus involving the spinal cord and occurs without input from the brain

1. sensory stimulus detected by sensory receptors
2. sensory neurons carry info via a sensory (afferent) pathway to spinal cord
3. interneurons in spinal cord initiate an involuntary motor movement
4. this is relayed to motor neurons and carried via a motor (efferent) pathway to muscles
5. muscles perform reflex response without input form the brain

Question 6

Peripheral nervous system

Answer 6

all nerves outside the CNS that carry messages between the CNS and muscles, organs and glanda throughout the body

has 2 subdivisions:
- somatic nervous system
- autonomic nervous system

Question 7

Somatic nervous system

Answer 7

controls skeletal muscles

enables communication between the body and the CNS in 2 ways

1. carries sensory info gathered by our 5 senses towards the CNS
2. carries motor commands from the CNS to the skeletal muscles, enabling voluntary movements

Question 8

Autonomic nervous system

Answer 8

• controls the bodys internal environment in an autonomous or self-regulated manner (mostly without conscious awareness)

directly connected to:
- organs
- glands
- visceral muscles (smooth, involuntary mucles in blood vessels)
- stomach
- digestive tract
- other internal organs

responsible for basic life processes:
- digestion
- respiration
- heart rate
- blood pressure

major role in our experience of:
- stress
- fear
- anger

has 2 subdivisions;
- sympathetic nervous system
- parasympathetic nervous system

Question 9

Sympathetic nervous system

Answer 9

• increases arousal readying the body for a quick response
• dominates when under stress
• flight-or-fight-or-freeze response

Question 10

Responses by the sympathetic nervous system to a threat

Answer 10

• pupils dilating(allow more light into eyes to see better)
• heart rate, blood pressure and breathing rates increase (due to accelerate oxygenated blood flow to muscles in order to respond to threat)
• energy being diverted to the muscles from functions such as digestion to conserve energy for responding to threat
• increased sugar and fat being released into blood to provide energy for quick action