The Nervous System Flashcards
List the main areas of the brain.
- Cerebellum
- Cerebrum
- Midbrain
- Pons Varolii
- Medulla
Classify the nervous system according to structure and function.
-STRUCTURAL-
Central (CNS) - brain and spinal cord.
Peripheral (PNS)- cranial nerves and spinal nerves.
-FUNCTIONAL-
Somatic - motor (skeletal muscle) and sensory (senses)
Autonomic - viscera (sympathetic and parasympathetic)
Identify the lobes of the cerebral hemisphere.
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Describe the arrangement of the spinal cord.
- Supported and protected by vertebral column (continuous with brain stem)
- Terminates at conus medullaris
- 31 spinal segments and associated pairs of nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal)
Describe the protective membranes that surround the brain and spinal cords.
- DURA MATER-
Two layers of dense fibrous tissue, very strong and durable. Inner surface of skull and forms a loose sheath around spine.
-ARACHNOID MATER-
‘Middle layer’ passes over fissures, envelopes spinal cord
-PIA MATER-
Fine connective tissue containing many minute blood vessels, completely covers convulsions and dips into fissures.
Discuss the production, circulation and function of the cerebrospinal fluid (CSF)
- Secreted into each ventricle of the brain, passes back into blood through tiny diverticula of arachnoid mater.
- When CSF pressure is higher than venous pressure, it passed into the blood.
- Made of - water, mineral salts, glucose, plasma proteins, creatine and urea.
- Functions - supports and protects brain and spine, maintains uniform pressure around them, acts as a cushion and shock absorber and keeps them moist.
Describe the different components of a neurone
- Axon - carries nerve impulses away from the cell body.
- Dendrite - carries impulses towards the cell body and form synapses with other neurones
- Cell body - form the grey matter of the nervous system
- Nodes of ranvier - allow waste products and nutrients to leave/enter cell and allow nerve impulses to move along the neurone
- Schwann cells - the cells that lay down the protective myelin sheath around the axon
Distinguish between a neurone and a nerve
- NEURONE -
Specialised cells that process information. 4 basic types (sensory, motor, communication, computation). They communicate with one another and other tissues through dendrites and axons. - NERVES -
Carry electrochemical impulses/signals to and from different areas of the CNS. Nerve impulses travel along neurones. 2 types - sensory/afferent (respond to changes in environment) and motor/efferent (transmit impulses to the muscles and glands, can be somatic or autonomic)
What is a ganglion?
- A cluster of nerve cell bodies or a deep cluster of interconnected neurones.
- Process sensory information or control motor outputs.
Distinguish between afferent and efferent neurones.
- AFFERENT -
Sensory neurone, bring stimuli from senses to CNS - EFFERENT -
Motor neurone, brings responses from the brain to the muscles and glands from CNS.
Describe the structure and function of the myelin sheath.
- Consists of a series of Schwann cells arranged among the length of the axon
- Each one is wrapped around the axon so that it is covered by a number of concentric layers of Schwann cell plasma membrane.
- They increase the rate of transmission of signals.
Explain the sequence of ionic events that occurs during an action potential.
- When stimulated - permeability of the nerve cell membrane to ions (Na and K) changes
- Sodium channels open and sodium moved into the neurone from ECF.
- Potassium floods out causing depolarisation and action potential is created.
- Inside of the cell become positive.
- Repolarisation occurs when the sodium channels close and potassium channels open and potassium moved out.
Describe the sequence of events that occurs at the synapse.
- At the free end of the synapse, the axon of one neurone breaks up into minute branches which terminate in small swellings called synaptic nobs (boultons).
- At the end of the boultons are spherical synaptic vesicles containing chemical transmitters which are released into synaptic clefts.
- Chemical transmitters are secreted by nerve cells, actively transported along the nerve fibres and stored in synaptic vesicles.
List the common neurotransmitters
Acetylcholine Seratonin Dopamine Norepinephrine L-DOPA Tryptophan GABA Glycine Tryamine Glutamine
What is the function of the cerebellum?
Involved in the main maintenance of balance, posture and muscle tone.
What is the function of the cerebrum?
Mental activities (memory, intelligence, reason)
Sensory perception (pain, temperature, smell, touch, sight etc)
Initiation and control of voluntary muscle contraction
What is the function of the midbrain?
Involved in the function of visual and auditory mechanisms such as eye movement.
Some parts are also involved in the control of body movement
What is the function of the pons?
‘Message station’ between areas of the brain (relays messages from the cortex to cerebrum).
Also plays a role in sleep and dreaming.
What are the functions of the medulla?
- Decussation of the pyramids (motor nerves descend through here to spinal cord)
- Sensory Decussation (some sensory nerves descend through)
- Cardiac centre (controls heart rate and contraction force)
- Respiratory centre (controls rate and depth of respiration)
- Vasomotor centre (controls diameter of blood vessels)
- Reflex centre (sneezing, coughing and vomiting)
What does the frontal lobe control?
Motor cortex Intellect Mood Planning Social judgement
What does the parietal lobe control?
Somatosensory cortex
General sensation and taste
What does the temporal lobe control?
Auditory cortex
What does the occipital lobe control?
Visual cortex
Regarding the autonomic nervous system:
The main neurotransmitter substance released at target organs of the parasympathetic nerves is acetylcholine
