Nervous System Flashcards
(98 cards)
1
Q
Nervous system consist of
A
Central nervous system
Peripheral nervous system
2
Q
The CNS consist of
A
Brain
Spinal cord
(Occupy the dorsal body cavity)
3
Q
Function of the CNS
A
Command center of the nervous system
4
Q
PNS consist of
A
The nerves that e tend from the brain to the spinal cord
5
Q
PNS function
A
Carry impulses from the sensory receptors to the CNS and from the CNS to the glands or muscles
6
Q
Types of nerves
A
Cranial - carry impulses to and from the brain
Spinal - carry impulses to and from the spinal cord
7
Q
What are peripheral organs
A
Organs that are not part of the nervous system
8
Q
What is the only type of tissue that is anueral
A
Cartilage
9
Q
PNS subdivisions
A
Sensory/ Afferent
Motor/ efferent
10
Q
Sensory/ afferent division
A
Consist of nerves that convey impulses from sensory receptors to the CNS
11
Q
Types of sensory nerves fibres
A
Somatic
Visceral
12
Q
Somatic nerve fibres
A
Sensory fibers delivering impulses from the skin, skeletal muscles, and joints
13
Q
visceral sensory fibers or visceral afferents
A
fibers transmitting impulses from the visceral organs
14
Q
Motor/ efferent division
A
carries impulses from the CNS to effector organs: muscles & glands.
15
Q
Motor subdivisions
A
The somatic nervous system
The autonomic nervous system (ANS)
16
Q
The somatic nervous system
A
voluntarily, control our skeletal muscles.
17
Q
The autonomic nervous system (ANS)
A
involuntary, such as the activity of smooth and cardiac muscles and glands
18
Q
Subdivisions of the ANS
A
Sympathetic (stimulate)
Parasympathetic (inhibit)
19
Q
Nervous tissues are made up of which cells?
A
Supporting cells
Neurons
20
Q
Supporting cells are known as
A
Neuroglia, glia, glial cells
21
Q
CNS glia
A
Astrocytes
Microglia
Ependymal cells
Oligodendrocytes
22
Q
Astrocytes
A
Star shaped
23
Q
Microglia
A
Resident immune cells in the brain and spinal cord
Phagocytes
24
Q
Ependymal cells
A
Line the central cavities of the brain and the spinal cord. The beating of their cilia helps to circulate the cerebrospinal fluid that fills those cavities and forms a protective cushion around the CNS.
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Oligodendrocytes
Wrap their flat extensions, producing fatty insulating covering (myelin sheath) around CNS nerve fibres
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Supporting cells in the PNS
Schwann cells
Satellite celle
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Schwann cells
form the myelin sheaths around nerve fibers that are found in the PNS
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Satellite cells
act as protective, cushioning cells
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Neurons function
transmit messages (nerve impulses) from one part of the body to another.
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Common features in all the neurons
cell body, which contains the nucleus and is the metabolic center of the cell
Dendrites
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Structure of the neurons
**Cell body -** metabolic center of the neurons
**Nissl bodies -** rough ER
**Neurofibrils -** intermediate filaments that are important in maintaining cell shape
**Dendrites -** Neuron processes (extensions) that convey incoming messages (electrical signals) toward the cell body.
**Axon -** generate nerve impulses and typically conduct them away from the cell body (only one is present in wach neuron).
**Axon terminals -** contain tiny vesicles that contain neurotransmitters
**Myelin -** a whitish, fatty material that covers the neve fibers. Myelin protects and insulates the fibers and increases the transmission rate of nerve impulses
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Neurons functional classification
according to the direction the nerve impulse is travelling relative to the CNS.
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Neurons functional classification
**Sensory neurons-**
Carry impulses from sensory receptors (in the internal organs or the skin) to the CNS
most cell bodies are in ganglia in the PNS.
**Motor neurons-**
Neurons carrying impulses from the CNS to the viscera and/or muscles and glands
The cell bodies of motor neurons are usually located in the CNS.
**Association neurons (interneurons)-**
connect the motor and sensory neurons in neural pathways.
Their cell bodies are typically located in the CNS
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Neurons Structural Classification
based on the number of processes extending from the cell body
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Neurons Structural Classification
Unipolar - sensory neurons in PNS ganglia
Bipolar - eyes, nose
Multipolar
36
Unipolar neurons
only the small branches at the end of the peripheral process are dendrites. The remainder of the peripheral process and the central process function as axons; thus, in this case, the axon conducts nerve impulses both toward and away from the cell body.
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Nature of nerve impulses is
Electrochemical
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Resting state of the nerve
3Na+ out of the membrane
2K+ into the membrane
-70mvolts
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Depolarization
Na+ diffuses into the nerve through Na+ channel
Action potential initiates
+30mvolts
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Repolarization
After the propagation of the action potential, repolarization occurs. Potassium ions diffuse out of the cell as the membrane.
The ionic conditions of the resting state are restored later by the activity of the sodium-potassium pump. Three sodium ions are ejected for every two potassium ions carried back into the cell.
41
The steps in the previous cards are for which types of nerves
unmyelinated fibers
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How will the impulse travel in nerves with myelin sheath
saltatory conduction
They will jump from one node to another
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Transmission of the Signal at Synapses
electrical change opens calcium channels
Calcium causes the tiny vesicles containing the neurotransmitter chemical to fuse with the axonal membrane
porelike openings form, releasing the transmitter
The neurotransmitter molecules diffuse across the synapse* and bind to receptors on the membrane of the next neuron
If enough neurotransmitter is released, action potential will occur
neurotransmitter is quickly removed from the synapse, either by diffusion away, by reuptake into the axon terminal, or by enzymatic breakdown.
This limits the effect of each nerve impulse to a very short period.
44
Brain and spinal cord are protected by:
Bone (the skull and vertebral column)
Membranes (the meninges): The dura mater; The arachnoid mater; The pia mater
A watery cushion (cerebrospinal fluid)
Barriers: e.g. blood-brain barrier and blood-CSF barrier.
45
The cranial and facial bones are connected by
Sutures
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What does the skull contain?
cavities, or fossae, as well as foramina (openings) and canals through which nerves and blood vessels pass.
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What is the largest opening in the skull?
foramen magnum (located at the occipital bone)
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Cranial bones
Frontal bone, Occipital bone, Ethmoid bone, Sphenoid bone, Parietal bones (pair), Temporal bones (pair).
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The Meninges
Dura mater
Arachnoid mater
Pia mater
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Dura mater
outermost layer
double-layered membrane (Outer layer = the periosteum, Inner layer = meningeal layer)
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The arachnoid mater
middle layer
subarachnoid space is filled with cerebrospinal fluid.
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Meningitis
inflammation of the meninges
bacterial or viral meningitis may spread into the nervous tissue of the CNS. This condition of brain inflammation is called encephalitis.
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Diagnosis of meningitis
by taking a sample of cerebrospinal fluid from the subarachnoid space.
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CSF appearance
clear, almost colourless liquid, but it differs from plasma in the concentrations of electrolytes, glucose, and protein, which remain relatively constant.
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CSF function
Provides a cushion for the brain and spinal cord. and protects the fragile nervous tissue from blows and other trauma.
Act as a shock absorber
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CSF volume
150 ml
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CSF formation
Blood is filtered at the choroid plexus
CSF is formed in the ventricles and then flows into the subarachnoid space
CSF is absorbed into the dural sinuses via the arachnoid villi
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hydrocephalus
Only in infants
causes the head to enlarge as the brain increases in size
This is possible in an infant because the skull bones have not yet fused
treated surgically by inserting a shunt (a plastic tube) to drain the excess fluid into a vein in the neck or into the abdomen
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Blood brain barriers location
Brain Microvessels at the interface between blood circulation and the Central Nervous System.
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BBB function
protection of CNS from blood-borne substances
maintenance of its homeostasis by facilitating nutrient entry and eliminating metabolic wastes out of the brain
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BBB risks
Prevent drugs from reaching the brain
Acccumulation of waste (alzheimer)
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communication and control center of the body
Brain
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Responses include:
Involuntary
Voluntary
Both can be motor or cognitive
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Involuntary response
Maintain homeostasis
Regulated by autonomic nervous system
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Voluntary
Actions
Controlled by somatic nervous system
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4 major areas in the brain
Cerebral hemispheres
Diencephalon
Brain stem
Cerebellum
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Cerebral Hemispheres
(Cortex (Gray Matter), White Matter (has areas of grey matter), Basal nuclei (ganglia), Limbic System) = The largest and most obvious portions of the brain.
Right and left
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Cortex Lobes
Frontal
Parietal
Temporal
Occipital
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Frontal lobe
**Prefrontal-** intellectual function and personality
**Premotor-**voluntary/ skilled movement
**Motor Cortex-**voluntary movement
**broca's area-**speech
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Parietal lobe
**Somatosensory-**sensation (touch/ pain)
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Temporal lobe
**Auditory cortex-**hearing
**Olfactory cortex-**smell
**Wernicke's area (left cortex)-**Comprehension of speech/ memory
Close to the ear
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Occipital lobe
**Visual cortex-**vision
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Diencephalon
(Thalamus, Hypothalamus) = the central portion of the brain, surrounded by the hemispheres.
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Thalamus
Relay centre
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Hypothalamus
Control the endocrine system (release hormones)
Regulate the autonomic nervous system
Control the temperature/ body fluids (homeostasis)
Center for thirst and hunger
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Brain stem
(Midbrain, Pons, Medulla Oblongata, Reticular Formation) = The inferior portion of the brain.
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Pons
Medulla oblongata
Regulate cardiovascular and respiratory processes (inhalation)
Swallow/ cough/ vomitting reflex
Nuclei of 5 cranial nerves
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Cerebellum
located dorsal to the pons and medulla, below the occipital lobe.
Maintaining balance and position, coordinated movement
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Limbic system
Responsible for emotions
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Reticular activation system
Arousal/ awarness
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Basal nuclei
Coordination and control of body movements
Damage of the basal nuclei can cause parkinson disease, which will cause problems in starting and stopping the movement
82
Blood is supplied to the brain by the
internal carotid arteries and the vertebral arteries
internal carotid artery is a branch of a common carotid artery
83
internal carotid artery
includes the carotid sinus, which is the location of the pressoreceptors (or baroreceptors) that signal changes in blood pressure and the chemoreceptors that monitor variations in blood pH and oxygen levels.
84
Blockage of the arteries in the brain results in:
Stroke
85
Cranial nerves
12 pairs
Some of these nerves bring information from the sense organs to the brain; other cranial nerves control muscles; other cranial nerves are connected to glands or internal organs such as the heart and lungs.
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cranial nerve X
vagus nerve innervate many of the viscera.
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Traumatic brain injuries
caused by injury at the site of the blow, and also by the effect of the ricocheting brain hitting the opposite end of the skull.
88
concussion
brain injury is slight
The victim may be dizzy, or lose consciousness briefly
little permanent brain damage occurs
Reversible
89
contusion
marked tissue destruction
individual may remain conscious, but severe brain stem contusions always result in a coma lasting from hours to a lifetime
Irreversible
90
hemiplegia
one-sided paralysis
right motor cortex of the frontal lobe is most likely involved
91
Aphasias
common result of damage to the left cerebral hemisphere, where the language areas are located
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Spinal cord
constitute the white matter surrounding an internal butterflyshaped core of gray matter or nerve cell bodies.
continuation of the brain stem
Provides a two-way conduction pathway to and from the brain
major reflex center
cushioned and protected by meninges.
93
flaccid paralysis
Damage to the ventral root
nerve impulses do not reach the muscles affected; thus, no voluntary movement of those muscles is possible. The muscles begin to atrophy because they are no longer stimulated.
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quadriplegic
the spinal cord injury occurs high in the cord, so that all four limbs are affected
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paraplegic
only the legs are paralyzed
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Structure of a Nerve
Each fiber is surrounded by a delicate connective tissue sheath, an endoneurium.
• Groups of fibers are bound by a coarser connective tissue wrapping, the perineurium, to form fiber bundles, or fascicles.
• Finally, all the fascicles are bound together by a tough fibrous sheath, the epineurium
97
True or false
All spinal nerves are mixed nerves.
True
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