Nervous System Flashcards
1
Q
What is the Nervous System?
A
- The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body
- Contains the Central Nervous System and the Peripheral Nervous System
2
Q
How is the CNS protected?
A
- The Brain and Spinal cord needs to be protected as they are vital parts of the body
- There are structures that protect the CNS, they include; bone, membranes called meninges, cerebrospinal fluid (CSF)
3
Q
What is the role Bone in the Protection of the CNS?
A
- Outermost part is the protective layer
- Cranium protects brain
- Vertebral canal protects the spinal cord
4
Q
What is the role Meninges in the Protection of the CNS?
A
- Meninges are membranes formed by 3 layers of connective tissue, they cover the entire CNS
- Outer Layer, tough and fibrous, sticks close to the bones of the skull but not so close to the vertebral canal
- Middle Layer, contains loose mesh fibres
- Inner Layer, more delicate, contains blood vessels, sticks closely to the surface of the brain and spinal cord
5
Q
What is the role Cerebrospinal Fluid in the Protection of the CNS?
A
- Formed from the blood and it circulates around and through the CNS, eventually re-entering the blood capillaries
- Occupies the space between the middle and inner layers of meninges, it also circulate through cavities in the brain and through a canal in the centre of the spinal cord
- It is a clear watery fluid, which contains some cells, glucose, proteins, urea and salts
- Protection: Acts as a shock absorber, cushioning any blows or shocks the CNS may sustain
- Supports: The 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
6
Q
What are the main structures of the Brain?
A
- Cerebrum: largest part of the brain, surface is folded into convolutions
- Corpus Callosum: a large bundle of nerve that connects the left and right hemispheres
- Cerebellum: underneath the rear end of the brain, the folds are less prominent than those of the cerebrum
- Medulla Oblongata: joins the brain and spinal cord
- Hypothalamus: deep inside the brain, responsible for many important functions such as water balance and temperature
7
Q
What is the Cerebrum?
A
- Biggest part of the brain, involved in mental activities such as thinking, learning, memory, perception and control of voluntary muscle contraction
- Consists of an outer surface of grey matter known as the cerebral cortex
- Below the cortex is white matter and deep inside the cerebrum is additional grey matter called the Basal Ganglia
- The Cerebral Cortex is folded into patterns which greatly increase the surface area, these are called convolutions GYRI
- The convolutions are separated by SUCLi (shallow down folds) or fissures (deep down folds)
- Right and Left Cerebral Hemispheres are subdivided into 4 lobes: frontal, parietal, temporal and occipital
8
Q
What are the three types of functional areas in the Cerebral Cortex?
A
~Sensory areas- receive and process nerve impulses from the sense
~Motor areas - send impulses to muscles especially for voluntary movement
~Association areas - Interpret information form the sense and make it useful
9
Q
What is the Cerebellum?
A
- Lies under the rear part of the cerebellum
- It is the second largest part of the brain and its surface is folded into a series of parallel ridges
- The outer folded part of the Cerebellum is grey matter (unmyelinated nerve fibre) and inside contains white matter (myelinated fibres) that branches to all parts of the cerebellum
- The Cerebellum exercises control over posture, balance and the fine coordination of voluntary muscle movement
- Functions that occur are unconscious
- Without the cerebellum our movements would be jerky and uncontrolled
10
Q
What is the function and role of the Medulla Oblongata?
A
- The Medulla Oblongata is a continuum of the Spinal Cord, about 3cm long
- Many nerve fibres pass through the medulla going to or from other parts of the brain
- The Medulla Oblongata plays an important role in automatically adjusting body functions, it contains;
~The Cardiac Centre, which regulates the rate and force of heartbeat
~Respiratory Centre, which control rate and depth of breathing
~Vasomotor Centre, which regulates the diameter of the blood vessels - There are also centres that regulate the reflexes of swallowing , sneezing and vomiting, all centres in the medulla oblongata are influenced and controlled by higher centres in the brain, particularly the hypothalamus
11
Q
What is the Spinal Cord and the function?
A
- The spinal cord extends from the foramen magnum, the large opening at the base of the skull to the second lumbar vertebrae, which is at about waist level
- About 44cm in length
- Function is to carry sensory impulses to the brain and motor impulses down from the brain
- The second functions is to integrate certain reflexes
- Contains grey matter in the centre, in the shape of a letter H
- The myelinated nerve fibres of white matter are arranged in bundles known as ascending and descending tracts
- Ascending tracts are sensory axons that carry impulses upwards towards the brain
- Descending tracts contain motor neurons that conduct impulses downwards away from the brain
12
Q
What is the Peripheral Nervous System?
A
- Contains nerve fibres
- Carries info to and from CNS and to groups of nerve cell bodies (ganglia) which lie outside brain & spinal cord
- Contains autonomic (which contain two sub divisions; sympathetic and parasympathetic) and somatic nervous systems
13
Q
What is the Function of the Somatic Nervous System?
A
- Carries messages to skeletal muscles and involved in voluntary muscle movements
- Takes impulses from the CNS to the skeletal muscles
14
Q
What is the Function of the Autonomic Nervous System?
A
- Apart of the Peripheral Nervous System
- Operates without conscious control and is regulated by groups of nerve cells in the Medulla Oblongata, Hypothalamus and Cerebral Cortex
- Body functions regulated by the autonomic nervous system include; heart rate, blood pressure, body temperature, digestion, release of energy, pupil diameter, airflow to lungs, defecation and urination
- Carry messages to heart muscle and other internal organs and the glands
15
Q
What is the Function of the Parasympathetic Nervous System?
A
- Apart of the Peripheral Autonomic Nervous System
- “Rest and Digest”
- Enables maintenance of normal bodily functions such as digesting and keeping the body at rest
e. g. constriction of pupils, stimulation of saliva, stimulation of stomach activity
