Human nervous system Part 1

Role of nervous system

1. Collects information about the changes in the internal and external environment
2. Transmits information collected via neurones to the processing centre
3. Process, intergrates and interprets the information received.
4. Coordinates body activities and conduct a response.

 

Organisation of nervous system

Central Nervous System

• Consists of the brain and spinal cord
• Process and integrates information, and initiate appropriate responses

Peripheral Nervous System

• Consists of 12 pairs cranial nerves and 31 pairs spinal nerves
• Cranial nerves – send nerve impulses to and from the brain (smell, vision, hearing, movement of eyeball, head & shoulder)
• Spinal nerves – send nerve impulses to and from the spinal cord (contain sensory and motor neurones)

 

Sympathetic and Parasympathetic nervous system

Sympathetic nervous system prepares the body for the “fight or flight” response during any potential danger.

Parasympathetic nervous system inhibits the body from overworking and restores the body to a calm and composed state.

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The Brain & Its Function

The brain consists of three parts:

1. Cerebrum
2. Cerebellum
3. Brain stem

Underneath the centre of cerebrum is thalamus, hypothalamus and pituitary gland

 

Front view of the brain

 

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Cerebrum

Outer region of cerebrum is the cerebral cortex

Cerebral cortex is a structure with many folds (increases surface area-helps store more data@memories)

Divided into hemisphere:

• Right hemisphere – controls the movement of left side of the body
• Left hemisphere – controls the movement of right side of the body

Side view (lateral view) of the brain

4 lobes of cerebrum:

• The frontal lobe – reasoning, motor skills, higher level cognition, and expressive language.
• The parietal lobe associated with processing tactile sensory information such as pressure, touch, and pain.
• The temporal lobe interpreting sounds and the language we hear, heavily associated with the formation of memories.
• The occipital lobe associated with interpreting visual stimuli and information. Damage to this lobe can cause visual problems such as difficulty recognizing objects, an inability to identify colors, and trouble recognizing words.

Side view (Medial view) of the brain

 

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Thalamus

• Small structure within the brain located just above the brain stem between the cerebral cortex and the mid brain (most upper part of the brain stem) and has extensive nerve connections to both.
• act as the relay centre – relay the signals from the sensory receptors to the correct area of cerebrum.

 

Hypothalamus

• Hypothalamus derived its name from its location in the brain; which is under/below the thalamus
• Pituitary gland is located at the end of hypothalamus
• The main role is to regulate homeostasis in the body. Hypothalamus responsible in regulating sleep, hunger, thirst, body temperature, water balance and blood pressure
• Hypothalamus control the actions of pituitary glands
• Example: when the osmotic pressure fall below normal, hypothalamus send signal to pituitary glands. Pituitary glands then release specific hormones that will increase the osmotic pressure to normal.

the hypothalamus (yellow)

hypothalamus and pituitary glands (pink)

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Cerebellum

• Located inferior to underneath the occipital lobe of the cerebrum and superior to the pons and brain stem
• Has 2 hemisphere like cerebrum.
• Function: Coordinates voluntary movements such as posture, balance, coordination, and speech, resulting in smooth and balanced muscular activity

 

       

Medulla oblongata

• The medulla oblongata (medulla) is one of the three regions that make up the brainstem. It is the most inferior of the three and is continuous above with the pons and below with the spinal cord.
• Functions: controls various autonomic nervous system functions including respiration, digestion, heart rate, functions related to the blood vessels, swallowing and sneezing.