Nervous System Flashcards
List the three structures involved in the protection of the central nervous system?
Bone, meninges, cerebrospinal fluid (CSF)
What does the bone do?
It is the outermost protective later e.g. the cranium protects the brain and the vertebral canal protects the spinal cord
What is the role of the meninges?
Are membraned formed by 3 layers of connective tissue, they cover the entire CNS;
Outer layer = tough & fibrous
Middle layer = loose mesh fibres
Inner layer = more delicate, contains blood vessels
What is the role of the cerebrospinal fluid (CSF)?
Occupies the space in the middle layer of the meninges in there brain cavities and in the centre of the spinal cord. It is a clear watery fluid which contains cell some cells such as glucose. Formed from blood
What are the three functions of the cerebrospinal fluid?
- Transports nutrients to the brain and removes waste
- Acts as a shock absorber by cushioning the CNS
- Supports the brain as it floats in the CSF fluid
What is the function of the cerebrum?
Involved in mental activities e.g. thinking, decision making, reasoning, learning, memory, intelligence and control of voluntary muscle contraction. left side is responsible for language ability, mathematics, logical thinking and decision making where as right side is responsible for musical/artistic ability
What is the structure of the cerebrum?
Outer layer which is composed of grey matter followed by white matter composed of myelinated nerve fibres. It contains the basal ganglia which is deep inside and contains grey matter. Contains folding ridges –> convolutions which increase surface area. Separated into four lobes; parietal, frontal, temporal, occipital
What is the cerebellum?
Second largest part of the brain. Folded outer surface which contains grey matter on the outside and white matter on the inside which branches to all parts of the cerebellum. It controls posture and balance and fine coordination of voluntary muscles. The control os unconscious
What is the hypothalamus?
In the middle of the brain which controls many body activities and maintains homeostasis which regulates autonomic nervous system functions such as heart rate, blood pressure, temperate, food and water intake
What is the medulla oblongata?
Nerve Fibres pass through medulla oblongata to or from the brain which regulates autonomic functions such as cardiac cycle, respiratory centre, vasomotor centre, and other reflexes such as swallowing, blinking,vomiting however all are controlled by higher centres such as the hypothalamus
What is a neuron or nerve cell?
The basic structural and functional units of the whole nervous system the three main components of a neutron are dendrites, cell body and the axon
What are multipolar neurons?
They are the most common, have 1 axon and multiple dendrites extending from the cell body. These include most inter neurones and motor neurons.
What are bipolar neurons?
They have 1 axon and 1 dendrite, axon and dendrite may have branches on the ends these occur in the eye, ear, nose where they take impulses from the receptor cells to the other neurons
what are unipolar neurons?
Unipolar neurons have 1 axon and the cell body is to one side of the axon, are most sensory neurons that carry messages to the spinal cord
What is the difference between a nerve fibre and a nerve ?
A nerve fibre is any long extension of cytoplasm of a nerve cell boy, although the term i usually referred to as an axon. A nerve is a bundle of nerve fibres held together by connective tissue
What is a synapse?
A small gap between one neuron and the next, which is transmitted in the form of a chemical message
What are neurotransmitters?
special chemicals released from the axon which diffuse across the synapse –> dendrite–> cell body
What is a neuromuscular junction?
Tiny gap between axon and muscle
What is a reflex?
A rapid, autonomic response to a change in external or internal environment which is one ewe the body achieves homeostasis.
What are the four properties of a reflex?
- Stimulus: is required to trigger off a reflex, not spontaneous
- Involuntary: occurs without any conscious thought
- Rapid: Only a small number of neurons
- Stereotyped: It occurs in the same way each time it happens
What is the reflex arc or spinal reflex?
Name given to a pathway of nerve impulse from receptor to effector muscle. Impulses are sent to the brain after the response has taken place. They protect the body form injury e.g. sneezing, coughing, vomiting
What is the spinal nerve?
Contains the dorsal root ganglion which conatins sensory neurons that have cell bodies and the ventral root which contains the axons of motor neurons
What are the components of a reflex arc?
- Sensory neuron - carries impulse from receptor to CNS
- Receptor - end of sensory neuron receptor reacts to change
- Effector - receives the impulse and carries out the appropriate response
- Motor neuron - carries impulse to the effector
- Synapse - there is at least one synapse impulse may pass direct to motor neurone or one or more inter neurons and then to motor neurones
What is the role of the autonomic nervous system?
Part of the peripheral nervous system in which it controls the body’s internal environment. It is involved in homeostasis mechanisms that keep internal environment constant which usually operates without conscious control
What of the somatic nervous system?
Part of the peripheral nervous system in which it controls voluntarily bodily movement and enables skeletal muscle movement
What is the role of the sympathetic nervous system?
The primary function of the sympathetic system is to stimulate yourfight-or-flight response which is a physiological reaction that happens in response to a perceived harmful event, attack or threat to survival
What is the role of the parasympathetic nervous system?
The parasympathetic system enables you to maintain normal functions such as digesting and keeping the body at rest.
What is the difference between the nervous and endocrine system?
The nervous sends messages in the form of electrical impulses and neurotransmitters along the membrane of neurones which are rapid where as endocrine system sends messages in the form of hormones by the bloodstream which affects all body cells and are slower - may take a few days to cause a response
What is a nerve impulse?
The message travels along a nerve fibre which are transmitted quickly making it possible for the body to respond rapidly to any change in the internal or external enviroment
What does a nerve impulse involve?
A nerve impulse is an electrochemical charge that travels along a nerve fibre - it involves a change in electrical voltage that is brought about by changes in the concentration of ions inside and outside the cell membrane
How fast does a nerve impulse travel?
The speed at which a nerve impulse travels at depends whether the nerve fibre is myelinated and unmyelinated and also the diameter of the fibre
How do nerve impulses travel in an unmyelinated fibre?
Travels steadily
How does a nerve impulse travel in myelinated fibres?
Myelin sheath is not continuous puntured my gaps called the nodes of ranvier in which nerve impulses jump from one node to the next -> saltatory conduction which allows the nerve impulse to travel faster.
