The central nervous system Flashcards by luv hi

what makes up CNS and PNS?

CNS :brain and spinal cord

PNS : Nerves make up the peripheral nervous system

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How does bones protect CNS?

Bones provide strong, rigid structure to protect the CNS:

Cranium is the part of the skull that protects the brain

Vertebrae protects the spinal cord

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How many layers does meninges have?

Three

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What is meninges?

Layers of connective tissues forming membranes.

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Where can meninges be found?

Found inside the bones, and covering the surface of the brain and spinal cord

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What is the outer meningeal layer?

Dura mater

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Describe structure of dura mater

Tough and fibrous similar to rubber glove

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Where does dura mater located ?

It sticks closely to the skull, but on the inside of the vertebral canal there is a space containing fat

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Function of space containing fat, connective tissues and blood vessels

serve as padding & allow the spinal cord to bend

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Describe feature of arachnoid mater

Loose mesh of fibres

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Where is the arachnoid located?

middle miningeal layer

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Describe feature of the Pia mater

Contains many blood vessels & sticks closely to surface of brain and spinal cord

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Where is Pia mater located?

the inner meningeal layer

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What is cerebrospinal fluid?

Clear, watery fluid containing a few cells and some glucose, protein, urea and salts

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What are the functions of cerebrospinal fluid?

Functions:
Protection - shock absorber, cushioning any blows or shocks the CNS may sustain

Supports the brain - brain is suspended inside the cranium and floats in the fluid that surrounds it

Transport - takes nutrients to the cells of the brain and spinal cord and carries away their wastes

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What does the CNS consists of ?

The central nervous system consists of:
grey matter - consist of nerve cell bodies, dendrites & unmyelinated fibres.
white matter - composed of myelinated fibres

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What are the parts of the brain?

Parts of the brain include: Cerebrum, cerebellum, hypothalamus, medulla oblongata and corpus callosum

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Describe cerebrum

Biggest part of the brain

Consists of :
outer surface of grey matter known as the cerebral cortex
grey matter deep inside the cerebrum called basal ganglia
inner white matter

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Describe cerebral cortex

The cerebral cortex is greatly folded which increase its surface area for a large number of neurons

Folding produces rounded ridges called convolutions (or gyri; singular gyrus)

How are convolutions separated by ?

shallow downfolds called sulci (singular ‘sulcus’)

deep downfolds called fissures

What is the deepest fissure ?

The longitudinal fissure (deepest fissure) almost split the cerebrum into two halves – the left and right cerebral hemispheres

What are the lobes of cerebrum ?

The lobes of the cerebrum:
Frontal lobe
Temporal lobe
Occipital lobe
Parietal lobe 
Insula (deep inside the brain)

What are the functions of cerebral cortex ?

Functions of the cerebral cortex:

involved in mental activities such as thinking, reasoning, learning, memory, intelligence and sense of responsibility
perception of the senses
the initiation and control of voluntary muscle contraction

What are the three types of functional area in the cortex?

There are three types of functional area in the cortex:
sensory areas, which interpret impulses from receptors
motor areas, which control muscular movements
association areas, which are concerned with intellectual and emotional processes.

What is the association area involved in ?

Memory

How does the association area works?

Memories are not stored in individual memory cells in the brain: they are pathways of nerve cells. When a memory is stored, new links are made between neurons or existing links are modified.

What is basal ganglia?

Are masses of grey matter inside each hemisphere

What does the basal ganglia consists of ?

Consist of groups of nerve cell bodies associated with control of skeletal muscles

Within the CNS, bundles of nerve fibres are called

tracts

What are the three types of tracts?

- tracts that connect various areas of the cortex within the same hemisphere - tracts that carry impulses between the left and right hemispheres - tracts that connect the cortex to other parts of the brain or to the spinal cord.

What are corpus callosum ?

A bundle of nerve fibres that lies underneath the cerebrum at the base of the longitudinal fissure

What is the function of corpus callosum ?

Function: allow the two cerebral hemispheres to communicate with each other

Describe the function of cerebellum

Lies under the rear part of the cerebrum Its surface is folded into a series of parallel ridges The outer folded part of the cerebellum is grey matter Inside is white matter that branches to all parts of the cerebellum

What is the function of cerebellum ?

Functions: control posture, balance and | the fine coordination of voluntary muscle movement

To carry out these functions the cerebellum receives sensory information from:

the inner ear (for posture and balance) | stretch receptors in the skeletal muscles

Are impulses generated by cerebellum ?

All the functions of the cerebellum take place below the conscious level Impulses do not originate in the cerebellum and so without it we could still move, but our movements would be spasmodic, jerky and uncontrolled.

Where does the hypothalamus located ?

Lies in the middle of the brain & cannot be seen from the outside

What is the function of hypothalamus?

It controls many body activities, but it is mostly concerned with homeostasis

The hypothalamus regulates ?

``` the autonomic nervous system body temperature food and water intake patterns of waking and sleeping the contraction of the urinary bladder emotional responses the secretion of hormones and coordination of parts of the endocrine system acting through the pituitary gland ```

Describe medulla oblongata

The medulla oblongata is a continuation of the spinal cord | About 3cm long & extends from just above the point where the spinal cord enters the skull

What does the medulla oblonganta consists of ?

The medulla oblongata contains: the cardiac centre, which regulates the rate and force of heartbeat respiratory centres, which control rate and depth of breathing the vasomotor centre, which regulates the diameter of blood vessels

Who controls all the centre in the medulla oblongata ?

Hypothalamus

Medulla oblongata also regulates ?

the reflexes of swallowing, sneezing, coughing and vomiting

Describe the spinal cord

The spinal cord is a roughly cylindrical structure It extends from the foramen magnum (opening at the base of the skull) to the second lumbar vertebra

Where does the white and grey matter located in spinal cord?

The grey matter of the spinal cord is at the centre, surrounded by the white matter

The myelinated nerve fibres of the white matter are arranged in bundles called:

Ascending tracts - sensory axons that carry impulses upwards, towards the brain Descending tracts - motor axons that conduct impulses downwards, away from the brain

Spinal cord functions:

Carry sensory impulses up to the brain & motor impulses down from the brain integrate certain reflexes (fast, automatic responses)