Topic C - Nervous system, neurological diseases and the eye part 1 Flashcards
What are the major organs and structures in nervous system?
Brain, spinal cord, nerves
What are the accessory structure in nervous system?
Meninges, sympathetic chain of ganglia
what are the 2 main functions of nervous system?
- Transmit electrical signals
* Allows brain communicate with the body
Which 2 organs make up central nervous system (CNS)
- Brain
2. Spinal cord
what makes up the peripheral nervous system (PNS)
Consists mainly of the nerves that extends from the brain and spinal cord
-Cranial nerves (from the brain)
-Spinal nerves (from the spinal
cord)
name the 12 pairs of cranial nerves and their function
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- Olfactory nerve = for smell (s)
- Optic nerve = For vision (s)
- Oculomotor nerve = For eye movement (m)
- Trochlear nerve = For eye movement (m)
- Trigeminal nerve = Motor for chewing, sensation of facial skin and mucosa of nose and mouth (s/m)
- Abducens nerve = For eye movement (m)
- Accessory nerve = For eye movement (m)
- Vestibulocochlear nerve = For balanc e and hearing (s)
- Vagus nerve =sympathetic and parasympathetic functions (s/m)
- Glossopharyngeal nerve = For swallowing and saliva production (s/m)
- Facial nerve = Motor for facial expression, sensory for taste (s/m)
- Hypoglossal nerve = For tongue movement (m)
describe spinal nerves
- Stem out from the spinal cord
2. Include nerve fibres of the sensory (going into cns) and motor neurons (going out of cns)
what are the 3 types of neurons?
- Sensory (afferent) neurons - carry signals from the outer parts of your body (periphery) into the CNS. Can be Bipolar neurons – one dendrite and one axon (found in the eye) OR Unipolar neurons – one dendrite, one axon with cell body push off to the side. Many cell body will grouped to form ganglia
- Motor (efferent) neurons - carry signals from the CNS to the outer parts (muscles, skin, glands) of your body. Multipolarneurons – multiple dendrites and an axon
- Interneurons - connect various neurons within the brain and spinal cord.
what are the 4 main area of the brain?
- Cerebral hemispheres (cerebrum)
- Diencephalon
- Brain stem
- Cerebellum
what is the cerebrum, what id its function and what are the 4 lobes within it?
It is the largest part of the brain and is composed of right and left hemispheres.
function: It performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement.
Four lobes:
- Frontal lobe
- Temporal lobe
- Parietal lobe
- Occipital lobe
what are the functions of the frontal lobe, temporal lobe, parietal lobe and occipital lobe
Frontal Lobe (motor)
• Sends impulses to skeletal muscles
Imp: in movement, etc
Parietal lobe (sensory)
• Receives impulses from the body’s sensory receptors
Imp: in calculation, reading/writing, etc
• Temporal lobe (hearing)
for hearing
• Occipital lobe (visual)
the visual processing center of mammalian brain containing most of the anatomical region of the visual cortex
describe the grey and white matter of the cerebrum
Cerebral cortex (Gray matter) – superficial layer Contain cell body & dendrites of neurons and unmyelinated axons (causes grey colour)
White matter – deeper layer
Composed of myelinated axons carrying impulses to, from, or within the cortex
Contains islands of gray matter known as basal nuclei e.g. caudate nucleus, putamen, globus pallidus
where is the diencephalon? what does it consist of?
Sits on top of the brain stem
Enclosed by cerebral hemispheres
Consists of the:
• Thalamus
• Hypothalamus
• Epithalamus
what is hypothalamus and what are its 3 functions?
An important autonomic nervous system centre
• Regulate body temperature, water balance and metabolism
• Centre for drives and emotions e.g. thirst, appetite, sex, pain, pleasure
• Regulate the release of hormones by pituitary gland
If Tumour is found in pituitary gland,
- Cause hemianopia
Visual field loss
what does the brain stem consist of and what are their functions?
1,Midbrain Convey ascending (sensory) and descending (motor) impulses. Contains reflex centres involved in vision and hearing
2.Pons
Mostly made up of fibre tracts. Contains important nuclei involved in the control of breathing
3.Medulla oblongata
An important fibre tract area Contain centres that control heart rate, blood pressure, breathing, swallowing, vomiting etc
where is the cerebellum and what is its function?
Found under the occipital lobe of the cerebrum, posterior to the pons and medulla oblongata of the brain stem
• Has two hemispheres and a convoluted surface
• Made up of outer gray matter and inner white matter
Function:
• Provide precise timing for
skeletal muscle activity
• Control balance and equilibrium
how is the cns being protected? (4 ways)
- Hard bony structure: skull (brain), vertebral column (spinal cord)
- Membranous structure: Meninges
- Watery cushion: cerebrospinal fluid (CSF)
- Blood-brain barrier:
Composed of the least permeable capillaries in the
whole body
• Control the content of CSF and therefore the microenvironment of the brain
• Pressure within CSF = intra-cranial pressure (ICP)
• It will raise if any growth in the brain.
what are the two main types of cell in nervous tissue?
- Neurons (nerve cell)
- Supporting cells (Also known as neuroglia or glial
cells (nerve glue)) –> help nerve cells w their functions
-Astrocytes
-Microglia
-Ependymal cells
-Oligodendrocytes
what are the 3 main parts of the neuron?
Cell body
dendrites
axons
what is the function of cell body?
Contains nucleus and organelles for protein synthesis (= control centre)
Eg. Protein neurotransmitter (acetycholine)
released from the knob at the end of nerve
cell for a muscle cell (skeletal muscle) to
contract
what is the function of dendrites?
Receive information from various pathways
• (Conduct impulses toward the cell body)
*Neurons may have 1-1000 of branching dendrites.
what is the function of axons?
carry nerve impulses/signals (in form of
neurotransmitter) along its length to the synaptic knobs (the axonal transport), which branches in the terminal arborization (arbor = tree)
• The synoptic knobs (many of them) forms synapse (junction) with another cell, a gland cell, or the
dendrite of another nerve cell
• Therefore one neuron can stimulate hundreds of other cells (eg. muscle cells) ina large unit
- Each neuron only has 1 axon, arising from the axon hillock / trigger zone
- The axon is intermittently covered b y myelin sheath, white in color. (cell body and dendrite do not have)
what is myelin and its function?
Myeline is lipid rich and it insulated the axons like the wire coating insulates the wires of electrical appliances
But, myeline has gaps, called nodes of Ranvier, which is very important in the conduction of nerve impulses
*In CNS:
• White matter, in brain and spinal cord, is concentration of myelinated axons.
• Gray matter, in brain and spinal cord, is concentration of dendrites, cell bodies and unmyelinated axons.
In PNS:
Peripheral nerves have myelinated axons.
what are the 4 support cells found in CNS?
- Astrocytes
- Microglia
- Ependymal Cells
- Oligodendrocytes
describe astrocyte and its function
- Star-shaped cells
- Have numerous cytoplasmic projections with swollen ends which cling to neurons
- Anchor neurons to the blood capillaries
- Mediate nutrient supply
- Protect neuron from harmful substance
- Control the chemical environment in the brain
describe microglia and its function
-Spiderlike phagocytes
Function: disposal of debris, including dead brain cells and bacteria
describe Ependymal Cells and its function
- Line the cavities of the brain and spinal cord
- Its cilia helps to circulate cerebrospinal (CSF) fluid that fills the cavities
describe Oligodendrocytes and its function
Wrap their flat extensions tightly around the nerve fibres
-Produce myelin sheath around nerve fibers in the central nervous system
what are the 2 support cells of the PNS and their functions?
1.Satellite cells
Protect cell bodies of neurons
- Schwann cells
Form myelin sheath around axons in the peripheral nervous system
How are nerve impulses generated and transmitted through a
neuron?
- Cell body
- control centre
- generate impulses by a stimulus - Dendrites
- Receive information from various pathway - Axons
- carry nerve impulses/signals (in form of neurotransmitter) to synaptic knobs (terminals) - The synapse
- Neurotransmitter molecules transmitted to receptors through synaptic cleft (the gap)
what are the 5 basic elements of a reflex arc that is caused by a stimulus?
Receptor – sensory neuron – integration center/interneuron (eg.spinal cord) – motor neuron - effector
describe function and give eg of sensory neuron
-Carries impulses from sensory receptors to the CNS
• Cell body of sensory neurons are always found in a
ganglion outside the CNS
- The dendrite endings are usually associated with specialized sensory receptors that varies in complexity
• E.g. Pain receptor (bare nerve endings)
Cutaneous receptor (skin)
Proprioceptors (muscle & tendon)
Vision, hearing, taste, smell, equilibrium receptors
describe function of motor neuron
-Carries impulses from the CNS to the viscera and/or muscles and glands
• Cell body of motor neurons are always located in the CNS
describe function of Inter Neurons
- Connects the sensory neurons and the motor neurons
* Cell body of interneurons are always located in the CNS
