Unit 5 - Nervous system

Question 1

Two parts of the central nervous system

Answer 1

Vertebral column and spinal chord

The brain

Question 2

Vertebral column and spinal chord

Answer 2

• Main pathway for information connecting the brain and peripheral nervous system

Question 3

The brain

Answer 3

• Main control centre
• Accepts and co-ordinates endless information from all pats of the body
• Has six main parts: Cerebrum, Cerebellum, Brain stem, Deincephalon, Limbic system, and Renticular activating system
• Note: The optic nerve and therefore the eye is considered part of the brain

Question 4

Peripheral nervous system

Answer 4

Consists of those parts of the nervous system that lie outside the CNS
- Carries information in and out of the CNS via nerves which include: 12 pairs of cranial nerves & 31 pairs of spinal nerves
- PNS is responsible for the beating of the heart and the digestive system, and all other voluntary neuromuscular controls
- Contains both autonomic and somatic components

Question 5

Autonomic nervous system and its two parts

Answer 5

The involuntary contraction of cardiac muscle and the smooth muscles of our internal organs are regulated by the ANS. (Automatic)

1. The ANS is comprised of two opposing systems:
   - The Sympathetic Nervous System.
   Causes localized bodily adjustments to occur (sweating or cardiovascular changes, heart rate increase/decrease, pupils dilating, etc.)
   - Prepares body for emergencies (i.e. releases adrenaline, increases heart rate, widening of the blood vessels)
   - “Fight or flight” responses to deal with imminent danger
2. Parasympathetic Nervous System:
   - Returns body to normal (after it’s been altered by the sympathetic system)

These 2 systems work in unison. The Sympathetic Nervous System makes the changes and the Parasympathetic Nervous System returns it to normal.

Question 6

Somatic nervous system

Answer 6

The SNS handles the muscles in our extremities allowing us control of our arms and legs to move about.
Contains both afferent and efferent nerve fibres:
- Afferent (Sensory) nerves: Send information to the CNS
- Efferent (Motor) nerves: Send instructions to skeletal muscle
- Through this system, the PNS receives and processes information from the receptors in the skin, in voluntary muscles, tendons and joints and gives us the sensations of touch, pain, heat, cold, balance, body position and muscle action.

Question 7

What are the 2 opposing systems in the Autonomic Nervous System and what are they responsible for?

Answer 7

1. The Sympathetic Nervous System:
   - Causes localised bodily adjustments to occur (sweating or cardiovascular changes, heart rate increase/decrease, pupils dilating, etc.)
   - Prepares body for emergencies (i.e. releases adrenaline, increases heart rate, widening of the blood vessels)
   - “Fight or flight” responses to deal with imminent danger
2. Parasympathetic Nervous System:
   - Returns body to normal (after it’s been altered by the sympathetic system)
   - These 2 systems work in unison. The Sympathetic Nervous System makes the changes and the Parasympathetic Nervous System returns it to normal.

Question 8

Efferent vs Afferent Neuron

Answer 8

• Afferent (Sensory) nerves: Send information to the CNS
• Efferent (Motor) nerves: Send instructions to skeletal muscle

Question 9

What is a reflex?

Answer 9

• A reflex is a natural response designed to protect you from harm and danger
• They involuntary movements that happen very quickly

Question 10

Types of reflexes:

Answer 10

If the command centre for reflex is in the brain = cerebral reflex, in the spinal cord =
spinal reflex
There are 2 types of reflexes and these relate to the divisions of the nervous system.

Autonomic reflexes (ANS) – involve smooth & cardiac muscle and glands. They regulate digestion, elimination, BP, salivation & sweating.

Somatic reflexes (SNS) – involve skeletal muscle, ex. Stretch reflex and withdrawal reflex.

Question 11

What is a neuron?

Answer 11

Neurons transmit information to each other through a series of connections that form a circuit. We examined the anatomy of a neuron during the muscular system unit.

Question 12

What are the three types of neuron?

Answer 12

1. Sensory Neurons: detect or sense information from the outside world (ex. light, sound, touch & heat)
2. Motor Neurons: send signals away from the CNS and get a response (ex. moving your leg or arm)
3. Interneurons: connect neurons to each other (depending on the type of reflex there may or may not be an interneuron)

Question 13

What is a reflex arc?

Answer 13

The reflex arc is an example of a simple circuit which allows an organism to respond rapidly to inputs from sensory neurons and consists only of a few neurons.

1. Receptor recieves an initial stimulus
2. Sensory nerve carries impulse to the spinal column or brain
3. Intermediate nerve fibre interprets signal and issues appropriate response
4. Motor carries response from spinal chord to the muscle or organ
5. Effector organ carries out response

Question 14

What is a propriceptor?

Answer 14

• Specialised sensory receptors found in tendons, muscles, joints and the inner ear that can detect the motion or position of the entire body or a limb by responding to stimuli from within the organism.
• They provide information about the state of muscle contraction, the position of body limbs, and body posture and balance.
• Afferent (sensory) input from two sensory receptors: tendon organs and muscle spindles, provide this feedback and control over muscles.
• The proprioceptor system plays an important role in physical movement. Tendon organs and muscle spindles continuously monitor muscle actions and are essential components of the neuromuscular system. They tell the nervous system about:
  1. the state of muscle contraction
  2. act as a safety device
  3. allow the nervous system to respond accordingly