Chapter 4.1 Central Nervous System✓ Flashcards
Define the role of the nervous system
The role of the nervous system is to receive and process information from sense organs and bring about responses to the information received.
What are the two divisions of the nervous system?
The Central Nervous System (CNS) and the Peripheral Nervous System (PNS)
What is the central nervous system made up of and what is its role?
It is made up of the brain and the spinal cord and its role is to receive information from all over the body and process it.
What is the peripheral nervous system made up of and what is its role?
It is made up of nerves that carry messages to and from the CNS and receptors, to muscles and glands in your body
How do the central nervous system and the peripheral nervous system link?
They link by transmitting signals between the brain, spinal cord (CNS) and the body’s receptors, muscles and gland (PNS)
What are the three structures that protect the CNS?
-bone (cranium and vertebrae)
-membrane called meninges
-cerebrospinal fluid
What bone is the brain protected by?
The cranium
What bone protects the spinal cord?
The vertebral canal
What do the bone provide for the brain and spinal cord?
A strong and ridged structure to protect the structures underneath
What are the three layers of menings?
-Dura mater
-Arachnoids mater
-Pia mater
What is a meninge?
Meninges are membranes/connective tissue that cover the brain and the spinal cord
Describe the dura mater layer.
-The outermost layer
-Tough and fibrous
- Provides a layer of protection for the brain
Describe the arachnoid mater layer.
-The middle layer
-Loose mesh of fibres
Describe the pia mater layer.
-The inner layer
-Delicate layer
-Contains blood vessels and sticks closely to the surface of the brain and spinal cord
Define cerebrospinal fluid (CSF)
Cerebrospinal fluid is a protective structure that occupies a space between the middle and inner layer of the meninges (between the arachnoid and pia layer)
Where does CSF circulate through in the brain and spinal cord?
Cerebrospinal fluid ciruclates through cavities in the brain and through a canal in the centre of the spinal cord
What does CSF contain.
Cerebrospinal fluid is a clear, watery fluid containing a few cells and some urea, glucose, protein and salts.
What are the three functions of the CSF?
-Protection: Acts as a shock absorber, cushioning any blows or shocks the CNS may sustain
-Support: The brain is suspended inside the cranium and floats in the fluid that surrounds it.
-Transport: The CSF is formed from the blood, and circulates around through the CNS before eventually re-entering the blood capillaries. During this circulation it takes nutrients to the cells of the brain and spinal cord and carries away their waste
Define the cerebrum
The cerebrum is the largest part of the brain
What does the cerebrum consist of?
It consists of a thin layer (2-4 mm) of grey matter known as the cerebral cortex.
What does grey matter consist of?
It consists of neuron cell bodies, dendrites and unmyelinated axons.
What is white matter made out of?
Myelinated axons.
What gives white matter its colour?
The fatty natures of the myelin sheath gives its colour and texture.
What is the grey matter called that is deep inside the cerebrum?
basal ganglia
What is the function of the basal ganglia?
The basal ganglia, are associated with the control of skeletal muscles, play a role in initiating desired movements and inhibiting unwanted movements.
What is the purpose of the folding of the cerebral cortex?
To increase its surface area for a large number of neurons
What does folding produce in the cerebral cortex?
It produces round ridges called convolutions
What are the two terms called when convolutions are separated?
They are separated by either shallow downfolds called sulci (sulcus) or deep downfolds called fissures.
What is the deepest fissure called and what does it almost separate?
Its called the longitudinal fissure and it almost separates the cerebrum into two halves - the left and right cerebral hemispheres
What are the four lobes of the cerebral cortex?
-Frontal lobe
-Parietal lobe
-Temporal lobe
-Occipital lobe
What is regarded as the fifth lobe?
The insula
What are the functions of the frontal lobe?
-Thinking
-Problem solving
-Emotions
-Personality
-Language
-Control of movement
What are the functions of the parietal lobe?
-Processing temperature
-Touch
-Taste
-Pain
-Movement
What are the functions of the temporal lobe?
-Processing memories and linking them with senses
-Receives auditory information
What is the function of the occipital lobe?
-Vision
What are the functions of the insula?
-Recognition of different senses and emotions
-Addiction and psychiatric disorders
What are the three functional areas of the cerebral cortex and define them.
-Sensory areas: Interpret impulses from receptors
-Motor areas: Control muscular movements
-Association areas: Concerned with intellectual and emotional processes
Define corpus callosum
The corpus callosum is a wide bundle of white matter that links the two cerebral hemispheres
What joins the two hemispheres?
The corpus callosum
Where is the corpus callosum located?
It is located underneath the cerebrum at the base of the longitudinal fissure
Where is the cerebellum located?
It is located underneath the rear part of the cerebrum
Describe the structure of the cerebellum?
The outer folded part of the cerebellum is grey matter and inside is white matter that branches to all parts of the cerebellum.
What is the cerebellum responsible for?
It is responsible for posture, balance and the coordination of voluntary muscle movement.
Where is the hypothalamus located?
It lies in the middle of the brain and cannot be seen from the outside the brain
What is the main role of the hypothalamus?
To maintain homeostasis
What are the functions of the hypothalamus?
Functions include:
-The autonomic nervous system (involuntary processes), including heart rate and blood pressure
-Body temperature
-Food and water intake
-Patterns of walking and sleeping
-Contractions of the urinary bladder
-Emotional responses e.g. fear, anger, pleasure
-The secretion of hormones and coordination of
parts of the endocrine system.
-(Acting through the pituitary gland, hypothalamus regulates metabolism, growth, reproduction and responses to stress)
Define the medulla oblongata
The medulla oblongata is a continuation of the spinal cord.
What centres does the medulla oblongata contain and define them.
It contains:
-The cardiac centre: regulates the rate and force of
the heart beat
-Respiratory centres: Controls rate and depth of breathing -The vasomotor centre: Regulates the diameter of blood vessels
-In addition, other centres regulate:
-reflexes of swallowing, sneezing, coughing and
vomiting
How long is the spinal cord?
roughly 44cm long in an adult
What are the two main functions of the spinal cord?
-Carrying sensory impulses to the brain and motor responses from the brain.
-Integrating fast automatic responses called reflexes
What are ascending tracts in the spinal cord?
Bundles of sensory axons that carry impulses upwards towards the brain
What are descending tracts in the spinal cord?
Bundles of motor axons that conduct impulses downwards away from the brain.
What structure allows for the bending of the spine?
The space surrounding the spinal cord filled with fat, connective tissue and blood vessels which cushions and allows for flexibility for spinal movements.
How is the outermost meningeal layer of the spinal cord different from that of the cerebrum?
In the cerebrum, the outermost meningeal layer is fused to the bone where as in the spinal cord it is attached to the bone.
How are the grey matter and white matter arranges in the spinal cord?
The grey matter is centrally located and shaped like an “H” while the white matter surrounds it.
