Nervous System Flashcards
(49 cards)
What 2 things is the nervous system made of and their fucntion?
1- nerve cells - transmit nerve impulses
2- neuroglia - connective tissue which supports the neurones
Describe a nerve cell from top to bottom:
1- dendrites
2 - cell body / nucleus
3 - axon (transmits nerve impulses away from cell body)
4 - myelin sheath (white fatty substance covers the axon. speeds up nerve conduction).
5 - node of ranvier - that gaps in the myelin sheath along the nerve. speed up the passage of impulses.
6 - neurilemma - fine delicate membrane which surrounds the myelin sheath. (only is peripheral nerves)
7 - end feet / axon terminals - pass on the impulse to the dendrites of the next nerve cell
8- synapse - where one neurone meets another.
Name the 5 different types of nerves and nervous tissue and their function:
1- motor / efferent nerves (carry messages from brain or spinal to muscles or glans which act on the info).
2- sensory / afferent nerves (carry impulses from all parts of the body to the brain)
3- mixed (both motor and sensory. only place they are found is the brain and the spinal cord).
4- white matter (on the inside of brain and outside of spinal cord.)
5- grey matter (on the outside of the brain and inside of the spinal cord)
Describe what happens to a cell during a nerve impulse:
- Resting cells have lower concentration of sodium ions inside the cell. Concentration of potassium ions is higher outside.
- When stimuli are detected, axon membrane becomes temporarily permeable which means sodium ions rush in making the inside of the cell positively charged.
- After impulse has passed, cell returns to it’s resting state.
What are the three parts of the brain?
1 - the cerebrum
2- the cerebellum
3- the brain stem
What is the structure and function (3) of the cerebrum?
Structure: largest part of brain divided into 2. outer layer of grey matter. inside is white matter.
Function:
1- controlling voluntary movement
2- interpreting and perceiving conscious sensations eg pain, heat, cold
3- controlling mental activity eg memory, intelligence, reasoning
What is the structure and function (3) of the cerebellum?
Structure: small brain. grey matter outisde, white matter inside.
Function:
1- coordinating muscular activity, making sure movements are smooth and precise
2- subconsciously controlling and maintaining muscle tone and posture
3- maintaining balance and equilibrium of body
What is the structure and the function of the hypothalamus?
Structure: located deep within the cerebrum at the top of the brainstem. pituitary gland attached to it’s base.
Function:
1- regulation of body temperature, water balance and metabolism
2- Centre for drives and emotions such as thirst, appetite, sex, pain and pleasure.
3- Regulates pituitary gland and therefore main link between nervous and endocrine systems.
4- Secretes oxytocin and antidiuretic hormone for storage in the posterior pituitary.
Name the three parts of the Brain Stem
1- Midbrain
2- Pons Varolii
3- Medulla oblongata
What is the structure and function of the midbrain?
Structure: lies between the cerebrum and the cerebellum. 2cm long. consists of nerve cells and fibres.
Function: relay station of the brain. transmit messages to and from the spinal cord, the cerebrum and the cerebellum.
What is the structure and function of the pons varolii?
Structure: situated in front of the cerebellum, below the midbrain and above the Medulla Oblongata. consists of nerve fibres which bridge the gap between the two hemispheres of the cerebellum.
Function: transmits messages to and from the spinal cord and cerebrum.
What is the structure and function (4) of the Medulla Oblongata?
Structure: lowest part of the brain stem. It has white matter on the surface and grey matter on the inside.
Function: VITAL CENTRES
1- CARDIAC controls rate and force of heart contraciton
2- RESPIRATORY controls rate and depth of breathing
3- VASOMOTOR controls constriction and dilation of blood vessels
4- REFLEX responds to irritants thus controls vomiting, coughing, sneezing and swallowing.
What is the structure and function of the spinal cord?
Structure: extends from medulla oblongata through spinal vertebrae ending at first lumbar vertebrae. 31 pairs of spinal nerves and part of 1 cranial nerve.
Function: carries motor and sensory nerve fibres along it’s length. sends messages to and from the body and brain.
What are meninges?
membranes that protect the whole of the central nervous system.
What are the 3 thee laters of meninges and their structure?
1- dura mater / outer membrane
(double layer of tough fibrous membrane)
2- arachnoid mater
(delicate membrane positioned immediately under the dura mater. Connects to sub-arachnoid space and filled with cerebrospinal fluid).
3- pia mater
(thin, vascular membrane which closely covers the brain and spinal cord. supplies blood to the brain and spinal cord).
What is the structure and function (3) of cerebrospinal fluid?
Structure: clear, colourless fluid.
contains protein, glucose, salts and other substances.
secreted into ventricles in brain and circulates round. then reabsorbed into the venous sinuses of the body through arachnoid mater.
Function:
1- protects the brain and spinal cord. shock absorber.
2- keeps the pressure around the brain and spinal cord constant.
3- transports nutrients and removes waste and toxic substances.
How many pairs of cranial nerves and spinal nerves does the peripheral nervous system have?
Cranial - 12 pairs
Spinal - 31 pairs
What are cranial nerves?
They originate in the brain and relay information from head and neck regions.
sight, hearing, taste and smell.
Name the three divisions of the 5th trigeminal nerve and their functions:
1- Opthalmic
(sensory nerves supplying the lacrimal glands, conjunctiva of eye, eye lids, forehead, anterior part of scalp and muscous membrane of nose)
2- Maxillary
(sensory nerves supplying lower eye lids, upper gums, upper teeth and cheeks)
3- Mandibular
(sensory and mort nerves. supplying teeth and gums of lower jaw, ear and tongue. Motor supplying muscles of mastication)
What is the function of the 7th Facial nerve?
Motor nerve, supplies the muscles of facial expressions.
Sensory nerve, supplies taste from anterior part of tongue.
What are the 2 parts of the 11th accessory nerve and their functions?
1- cranial
(branches joining the vegus nerve to supply larynx and pharynx)
2- spinal
(branches supplying the trapezius and sternocleido mastoid)
Describe the breakdown of the different spinal nerves:
Cervical - 8 pairs
Thoracic - 12 pairs
Lumbar - 5 pairs
Sacral - 5 pairs
Coccygeal - 1 pair
Are spinal nerves sensory, motor or both?
both
Name the 6 plexus from top to bottom and the areas they supply:
1- Cervical Plexus - first four cervical nerves
(supplies muscles of the neck, shoulder and skin. also includes the phrenic nerve which sends impulses to the diaphragm telling it to contract)
2- Brachial plexus - lower four cervical and first thoracic nerve
(supplies muscles from base of the neck to the fingertips and skin).
3- Thoracic (intercostal) nerves
(Thoracic nerves supply chest muscles and main part of abdominal wall)
4- Lumbar plexus - first three lumbar nerves and part of fourth
(supplies skin and muscles of lower abdomen, thighs and groin)
5- Sacral plexus - lower two lumbar, first four sacral nerves
(supplies muscles and skin of pelvic area. includes sciatic nerve which supplies the hamstrings. then divides above knee into tibial and common peroneal nerves to supply lower leg)
6- Cocygeal Plexus
(supplies muscles and skin of pelvic area such as external sphincter of the anus, tissues of the perineum and external genitalia.
