LO 8/9 Flashcards
(90 cards)
1
Q
List the organs of the nervous system
A
- Brain
- Spinal cord
- Nerves - cranial and spinal
- Sensory organs - eyes, ears, specialized sensory organs, free nerve endings in skin
2
Q
What are the two main divisions of the nervous system?
A
- Central nervous system- brain and spinal cord, centrally located, integrative and control center (interprets incoming information and dictates response)
- Peripheral nervous system - nerves that extend to the peripheral parts of the body from the brain and spinal cord, communication Network between CNS and the rest of the body
3
Q
What are the two main divisions of the peripheral nervous system?
A
- Autonomic nervous system
- Somatic nervous system
4
Q
Describe the autonomic nervous system
A
- ANS for short
- Involuntary
- Visceral motor nerves
- Conducts impulses from CNS to cardiac muscle smooth muscles, and glands
5
Q
Describe the somatic nervous system
A
- SNS for short
- Voluntary
- Somatic motor nerves
- Conducts impulses from the CNS to skeletal muscles
6
Q
What are the two major divisions of the autonomic nervous system?
A
- Parasympathetic nervous system - cranial and sacral areas, rest and digest
- Sympathetic nervous system thoracic and lumbar areas, fight or flight
7
Q
What are the two types of cells found in the nervous system?
A
- Neurons (nerve cells)
- Glia / neuroglia
8
Q
Describe neurons
A
- The structural and functional units of the nervous system
- Consist of three main parts - dendrites, cell body, axon
- Classified according to function - sensory, motor, interneurons
9
Q
_________ are branching projections that conduct impulses to the cell body
A
Dendrites
10
Q
Describe the neuron cell body (soma)
A
- It is the main part of the neuron
- Contains the nucleus
- Found in or close to the central nervous system
11
Q
________ is a long, single projection from the neuron cell body that transmits impulses away from the cell body
A
Axon
12
Q
_______ neurons sense stimuli and conduct impulses from receptors all over the body to the brain and spinal cord
A
Sensory or afferent neurons
13
Q
________ neurons conduct impulses away from the brain and spinal cord toward muscles and glands (effectors)
A
Motor (efferent)
14
Q
Somatic motor neurons send impulses to ________ while visceral or autonomic motor neurons send impulses to _______
A
- Skeletal muscles
- Smooth and cardiac muscle, glands
15
Q
________ neurons conduct impulses from sensory neurons to motor neurons
A
Interneurons (central or connecting)
16
Q
Describe glia (neuroglia)
A
- Cells that provide support and protection for the nervous system
- Play a role in regulating function and structure of neurons - they are the glue that binds the cells of the nervous tissue together both structurally and functionally, allowing nervous system tissue to work as a coordinated whole
- They do not transmit nerve impulses
- They are five times more abundant than neurons
17
Q
What are the four types of glia?
A
- CNS-astrocytes, microglia, oligodendrocytes
- Pns - Schwann cells
18
Q
Describe astrocytes
A
- Relatively large compared to other glial cells
- Wrap around and secure small blood vessels to neurons
- Part of the blood-brain barrier - separate blood from brain tissue, protects brain from harmful substances that may be in blood
19
Q
Describe microglia
A
- Smaller than astrocytes
- Act as first and main form of active immune defense for CNS tissue
- Usually stationary, but if they sense any ‘trouble’ (e.g. tissue of the CNS becomes inflamed or damage), they quickly respond and act as macrophages to decrease inflammation and/or destroy any harmful substance to prevent potentially fatal damage to the sensitive CNS tissue
20
Q
Describe oligodendrocytes/oligodendrogli
A
- Oligo = few and dendro = branches
- They help hold neurons together by extending its branches to the axon of neurons (can wrap its branches around up to 50 axons)
- Forms the myelin sheath (neurilemma is outermost membrane) on axons in the CNS
21
Q
Describe the myelin sheath
A
- Is a fatty substance that electrically insulates axons
- Essential for proper function of nervous system / nerve impulse conduction
22
Q
In the cns, myelin is formed by ________, while in the pns myelin is formed by _______
A
- Ogliodendroglia
- Schwann cells
23
Q
_______are tiny uncovered gaps that are regularly spaced along the myelin sheath of the neuron
A
Nodes of ranvier
24
Q
Describe the nodes of ranvier
A
- Unmyelinated spaces along axons
- Since the nervous not insulated with myelin at these spaces, it is capable of generating electrical activity there
- Allows for rapid and effective transmission of a nerve impulse referred to as saltatory conduction
- Saltatory means jumping
25
Describe nerves
1. Made up of several bundles of axons (AKA fascicles) in the peripheral nervous system
2. Usually covered by a myelin sheath, so appear white in color
26
_______ is tissue compose primarily of myelinated axons, while ________ is tissue composed primarily of cell bodies and unmyelinated fibers
1. White matter
2. Gray matter
27
What is a nerve fiber versus a fasicle versus a nerve?
1. Nerve fibre is an axon
2. Fasicle is a bundle of axons
3. A bundle of fasicles is a nerve
28
Describe tracts
1. Bundle of axons in the central nervous system
2. Made up of white matter and gray matter
29
Describe nerve coverings
1. Individual axons nerve fibers, fascicles, and nerves are surrounded by thin layers of fibrous connective tissue that have specific names based on their location
30
The ________ surrounds individual axons of the nerve
1. Endoneurium
31
The _______ surrounds individual fascicles (bundles of axons) of nerves
1. Perineurium
32
The _______ surrounds the entire nerve
1. Epineurium
33
Nerve impulses are also called ______
Action potentials
34
Action potentials nerve impulses are constantly being conducted from ________ to ________ over ________
1. Receptors
2. Effectors
3. Neuron pathways
35
A ________ is a specialized neuron pathway that results in rapid involuntary or autonomic response to a stimulus
Reflex arc - a particular stimulus always causes the same reflex
36
What are the two types of reflex responses?
1. Contraction by a muscle
2. Secretion by a gland
37
Describe the five components of a reflex arc
1. A receptor - detects change and generates nerve impulse
2. Sensory/afferent neuron - transmits impulse to CNS
3. CNS-integrating center with one or more synapses (where interneurons are located)
4. Motor / effort neurons - transmits impulses from CNS to effector
5. Effector - a muscle or gland that performs the action/manifests the effect
38
Describe two neuron arcs and three neuron arcs
1. **Two neuron arcs** - simplest reflex arcs, consist of sensory neurons synapsing in the spinal cord with motor neurons (no interneuron); simple, unlearned reflexes; used by doctors to make sure the nervous system is working properly (knee-jerk or pupil dilation)
2. **Three neuron arcs** - consist of sensory neurons synapsing in the spinal cord with interneurons that synapse with motor neurons; associated with more complex responses such as response to injury / pain withdrawal reflex; provide automatic reactions that must occur quickly to ensure survival
39
What should you know about three neuron arcs?
1. Inter neurons are specific to three neuron arcs
2. Inter neurons are located entirely within the gray matter of the brain or spinal cord
3. These arcs determine what, if any, action needs to happen in response to a stimulus from the sensory neuron and will communicate this information accordingly with the motor neuron
4. The more threatening the sensory information is, the more likely it will get sent to the brain for more complex processing/integration
40
What is the one way impulse route (be specific)
1. Receptor slash sensory neurons - from dendrites to cell body to Axon
2. Synapse - microscopic space between neurons where neurotransmitters are released in order to promote the nerve impulse onto the next neuron
3. Interneuron (if it's a three neuron arc) through the axon, then cell body, to the next synapse
4. Motor neuron (ventral root) - synapse at neuromuscular or neuroglandular junction
5. Effector - the muscle or gland that will respond or put the nerve impulse into effect equals the reflex
41
Where is the cell body for receptor/sensory neurons located?
1. The dorsal root ganglion, which is in the pns near the spinal cord
42
Define nerve impulse
1. A self propagating wave of electrical disturbance that travels along the surface of a neurons plasma membrane. Also called an action potential
43
The membrane of a resting neuron has a slightly _______ charge on the outside and a _______ charge on the inside
1. Positive - due to excess Na+ on outside
2. Negative
44
How are action potentials triggered?
1. A stimulus (e.g.pressure, temperature, chemical changes) triggers the opening of Na+ channels in the plasma membrane of the neuron (starting at the dendrites) allowing Na+ to rush into the neuron
2. Inward movement of positive sodium ions leaves a temporary, slight excess of negative ions on the outside of the neurons membrane at the stimulated point - this marks the beginning of a nerve impulse
3. This electrical disturbance of the neurons membrane stimulates sodium channels in the adjacent sections of the membrane to soon open and so on and so on creating a self propagating wave that travels along the entire length of a neurons membrane
45
Describe presynaptic neuron versus post-synaptic neuron
1. Presynaptic neuron - before the synapse
2. Postsynaptic neuron - after the synapse
46
What are the three structures of a synapse?
1. Synaptic knob
2. Synaptic cleft
3. Plasma membrane of postsynaptic neuron
*Synapse ensures there's only one way transmission of a nerve impulse
47
Describe synaptic knob
1. Tiny bulge at the end of a terminal branch of presynaptic neurons Axon AKA (axon terminal)
2. Contains vesicles full of neurotransmitters
48
Describe synaptic cleft
Microscopic space between a synaptic knob and the plasma membrane of the postsynaptic neuron
49
What does the plasma membrane of postsynaptic neuron contain?
Contains receptors for neurotransmitters
50
Describe neurotransmitters
1. Chemicals by which neurons communicate
2. Released from the vesicles of the synaptic knob of axon terminals of a presynaptic neuron
3. Diffuse through the synaptic cleft where they bind to receptors in the membrane of the postsynaptic neuron
4. When they bind to the receptors, ion channels in the membrane of the postsynaptic neuron open, allowing the electrical impulse to continue
5. Their action in the synaptic cleft is short-term - once the impulse has been transmitted from the pre to postsynaptic neurons, neurotransmitter action is ended by either reabsorption or inactivation by special enzymes
51
There are at least 30 different types of neurotransmitters, what are the three major ones pertinent to this course?
1. Acetylcholine - major neurotransmitter of autonomic nervous system responses
2. Catecholamines (noradrenaline / norepinephrine, adrenaline/epinephrine, dopamine, serotonin) - sleep, mood, pleasure recognition, motor function
3. Endorphins and enkephalins - morphine like, natural painkillers (inhibit conduction of pain impulses)
52
What are the two major structures of the central nervous system?
1. Brain - protected by cranial bones / skull
2. Spinal cord - protected by vertebral column/spine
**Both brain and spinal cord are protected by meninges
53
What are the major divisions of the brain?
1. Brainstem - medulla oblongata, pons, midbrain (mesencephalon)
2. Cerebellum
3. Dyencephalon - hypothalamus, thalamus
4. Cerebrum
54
_______ is the lowest part of the brain stem (enlarged upward extension of the spinal cord)
Medulla oblongata
55
The _______ connects the medulla oblongata with a surface of the cerebeum (cerebral cortex)
Pons
56
The _______ is the part of the brain stem that is near the center of the brain
Midbrain (mesencephalon)
57
Overall, the brain stem is composed of bits of scattered white and gray matter. In the medulla, these bits are closely mixed together and referred to as the _________
Reticular formation
58
Describe the function of the brain stem
1. The gray matter functions as autonomic reflex centers (e.g. heartbeat, respiration, blood vessel diameter to vital centers such as medulla oblongata)
2. Sensory tracts in the brain stem conduct impulses to higher parts of the brain
3. Motor tracts in the brainstem conduct impulses from higher parts of the brain to the spinal cord
59
Describe the cerebellum
1. Second largest part of the brain
2. Connected to brain stem
3. Exterior is mostly gray matter and interior is mostly white matter
4. Helps control muscle contractions to produce coordinated movements so that we can maintain balance, move smoothly and sustain normal posture
60
Describe the components of the diencephalon
1. Hypothalamus - posterior pituitary gland, pituitary stock, areas of gray matter, one of the smallest parts
2. Thalamus - dumbbell-shaped, massive gray matter in each cerebral hemisphere, mostly dendrites and cell bodies of neurons that have axons extending upward into sensory areas of cerebrum
61
Describe the hypothalamus
1. The heart of subconsciousness
2. major center for controlling the ANS (involuntary actions)
3. Connects nervous and endocrine system (Master translator)
4. Controls hormone secretions via anterior and posterior pituitary glands (indirectly helps control secretion of most other endocrine glands)
5. Some of it's neurons make hormones that the posterior pituitary gland secretes into the blood - and some of its axons act as ductless glands as they secrete their own releasing factors that affect the interior pituitary gland
6. Functions include appetite control, body temp, water balance, sleep and wakefulness, pleasure, anger, sexual arousal, and pain
62
Describe the thalamus
1. Composed mostly of dendrites and cell bodies that have axons extending up toward the sensory areas of the cerebrum
2. Receives all sensory information (except for smell), then directs impulses from sensory organs to sensory areas of the brain for conscious interpretation
3. Association of sensations with emotions (e.g.pleasant or unpleasant emotion / feeling associated with sensations)
4. Place a role in the bodies arousal/alertness mechanism (alerts us to danger by prioritizing threatening impulsive/information)
63
Describe the structure of the cerebrum
1. Largest and uppermost part of the human brain
2. Outer surfaces has many ridges (gyri) and grooves (sulci)
3. It's two halves the (cerebral hemispheres) are connected by the corpus callosum - a wide, flat bundle of nerve fibers
4. The outer layer of gray matter is the cerebral cortex, composed mainly of dendrites and cell bodies of neurons
5. Divided into lobes named after the cranial bones - frontal lobe (motor control), parietal lobe (sensory control), temporal lobe (hearing), occipital lobe (vision)
6. Interior composed mainly of white matter (cerebral white matter is nerve fibers arranged in bundles called tracts)
7. Contains some gray matter called cerebral nuclei (basal ganglia) - function is related to automatic movements and posture
64
Describe the function of the cerebrum
1. Numerous functions due to the connections between its neurons with neurons in many other parts of the brain and spinal cord
2. Mental processing (e.g.consciousness, thinking, memory, sensations, emotions, control a voluntary movements, control of posture)
3. Commonly damaged by stroke leading to compromise of its functions
65
Describe the structure of the spinal cord
1. 17 to 18 in long in the average adult
2. Sits inside the spinal cavity (protected by vertebrae) - part of the CNS that is most susceptible to injury
3. Outer park composed of bundles of myelinated axons called spinal tracts which are functionally organized - all axons of one tract serve one general function
4. Interior is composed of gray matter (H-shape) made up of mainly cell bodies and unmyelinated dendrites and axons
66
Describe the function of the spinal cord
1. Center for thousands of spinal cord reflexes
2. Sensory tracts (ascending tracts) conduct impulses from sensory neurons/receptors up to the brain
3. Motor tracts (descending tracts) conduct impulses from the brain down to motor neurons/effectors
4. Spinal cord injury anesthesia and/or paralysis
67
Describe the coverings and fluid spaces that protect delicate nervous tissues
1. Coverings - cranial bones and vertebrae; cerebral and spinal meninges (dura/arachnoid/pia mater)
2. Fluid spaces - found in subarachnoid spaces of meninges, central canal inside spinal cord, and ventricles in the brain; filled with CSF (cerebral spinal fluid)
68
Describe cerebral and spinal meninges
1. Tough membranes
2. Form a tube like covering around the spinal cord and line the vertebral foramen of each vertebrae surrounding it
3. Also extends around the brain to completely enclose it
69
What are the three layers of the cerebral and spinal meninges?
1. Dura mater (hard mother) - tough outer layer, lines the vertebral canal
2. Arachnoid mater (spider web mother) - middle layer, cushioning layer (fluid - CSF in its spaces)
3. Pia meter (delicate mother) - innermost layer, covers the spinal cord
70
Where are fluid spaces found in the central nervous system?
1. Subarachnoid spaces (between Pia and arachnoid Mater of meninges)
2. In central canal inside spinal cord
3. Cerebral ventricles in the brain
These faces are filled with cerebrospinal fluid
71
Describe cerebrospinal fluid
1. Circulating, clear, plasma like fluid found in and around the brain and around the spinal cord
2. Continually forms from fluid/plasma filtering out of the blood at the arterioles of the choroid plexus
3. This fluid enters the ventricles of the brain and is now called CSF
4. CSF circulates around the brain, through spaces (ventricles) within the brain, in the space surrounding the spinal cord, and then is reabsorbed back into the blood
5. Total volume is 150 ml; replaced every three to four hours
6. Blockages anywhere along this path can lead to an accumulation of CSF - e.g. Hydrocephalus
7. Stored in the subarachnoid space
72
What are the functions of cerebrospinal fluid
1. Protect/cushion the brain and spinal cord from trauma - CSF prevents the brain from being crushed by its own weight approximately 2 to 3 lb
2. Supplies nutrients to the nervous system tissue of the brain and spinal cord
3. Acts as the brain and spinal cords lymphatic system - removes waste products; provides immunological protection to CNS nervous tissue
73
What is the peripheral nervous system and how many nerves does it include?
1. The nerves that connect to the brain and spinal cord to the rest of the body
2. 12 pairs of cranial nerves
3. 31 pairs of spinal nerves
74
Describe cranial nerves
1. Structure - 12 pairs are attached to the under surface of the brain
2. Function- conduct impulses between the brain and structures in the head and neck and in the thoracic and abdominal cavities
75
What are the 12 pairs of cranial nerves?
1. Olfactory- smell
2. Optic-vision
3. Oculomotor- moves eye
4. Trochlear- moves eye
5. Trigeminal - sensations of teeth, face, scalp, and chewing muscles
6. Abducens - move eye
7. Facial - facial expression, taste
8. Vestibulocochlear (auditory) - hearing and sense of balance
9. Glossopharyngeal - taste, swallowing, saliva, throat sensations
10. Vagus - numerous functions, including heart rate, breathing, and digestion
11. Accessory - moves neck / shoulder
12. Hypoglossal - moves tongue
76
What is a good mnemonic device to remember the cranial nerves?
Old Opie Occasionally Tries Trigonometry And Feels Very Gloomy, Vague, And Hopeless
77
Describe the structure of spinal nerves
1. Exit spinal cord and Branch to form the many peripheral nerves of the body's trunk and limbs
2. Plexus - nerve fibers for multiple spinal nerves that are "braided" together to form a single peripheral nerve
3. Identified by a letter and a number e.g. c1 or t8 (nerve exits Superior to its numbered vertebrae)
4. Each spinal nerve has two roots - **dorsal root** containing sensory fibers from sensory neurons in dorsal root ganglia; **ventral root** containing somatic (voluntary) and autonomic (involuntary) motor fibers that arise from the anterior lateral horns
78
What is the function of the spinal nerves?
1. Conduct impulses between the spinal cord and other parts of the body not supplied by cranial nerves (e.g. All parts of the body except the head)
2. Contain sensory and motor fibers
3. Conduct impulses necessary for sensations and voluntary movements
79
________ are specific areas of skin surface supplied by a single spinal nerve
Dermatomes
80
Describe the autonomic nervous system
1. One of the subdivisions of the pns
2. Consists of certain autonomic motor neurons that conduct impulses from the spinal cord or brain stem to cardiac muscle, smooth muscle, and glandular epithelial tissue
3. Regulates the body's autonomic or involuntary functions (e.g. Heartbeat, digestive contractions, glandular secretions) - essential to survival of the body
4. Has two divisions - sympathetic nervous system, parasympathetic nervous system
81
Describe the general functionality of the autonomic nervous system
1. Dendrites and cell bodies of some autonomic motor neurons (conduct impulses away from spinal cord and brain stem) are located in the gray matter of the spinal cord or brain stem
2. The axons of these autonomic motor neurons extend from the gray matter of the spinal cord or brain stem and end in the peripheral junction boxes called ganglia - they are called **preganglionic** neurons because they conduct impulses from the CNS to a ganglion
3. In the ganglia, the axon endings of the preganglionic neurons synapse with the dendrites or cell bodies of the **postganglionic** neurons, which then conduct impulses from the ganglia to **visceral effectors**
82
How are conduction pathways to visceral and somatic effectors from the CNS different?
1. Autonomic conduction path - consists of two neuron relays, impulse travels as follows: preganglionic neuron from the CNS ➡️ synapse at autonomic ganglia ➡️ across the synapse ➡️ post ganglionic neurons ➡️ visceral effectors
2. Somatic conduction paths - somatic (voluntary) motor neurons of the somatic nervous system, conduct impulses all the way from the CNS to somatic effectors with no intervening synapses (CNS ➡️ somatic effectors)
83
Describe the sympathetic nervous system (thoracolumbar system)
1. Sympathetic preganglionic neurons have dendrites and cell bodies in the gray matter of the thoracic and upper lumbar segments of the spinal cord
2. Axons of the preganglionic neurons leave the spinal cord by the ventral roots of the spinal nerves and then travel up or down to a nearby sympathetic ganglia where they synapse with many post-ganglionic neurons whose axons extend to spinal or autonomic motor nerves to terminate in visceral effectors
3. There are many post-ganglionic neurons involved, sympathetic responses are usually widespread, involving many visceral effectors/organs
4. Sympathetic postganglionic neurons have dendrites and cell bodies in sympathetic ganglia which are located in the front and on each side of the spinal column
5. The sympathetic ganglia are strung along the nerve fibers like beads which is called the sympathetic chain ganglia
6. Axons of postganglionic neurons travel in spinal nerves to blood vessels, sweat glands, and erector pili hair muscles all over the body
7. Separate autonomic nerves distribute many sympathetic post-ganglionic axons to various internal organs
84
Describe the function of the sympathetic nervous system
1. Serves as the emergency or stress system
2. Decreases non-essential functions e.g.digestion
3. Controls visceral effectors during all types of stressful/strenuous events/activities
4. Group of changes induced by sympathetic control is called fight or flight response - heart beats faster, most blood vessels constrict, sugar is released into blood, respiration increases
85
Describe the structure of the parasympathetic nervous system
1. Parasympathetic preganglionic neurons have dendrites and cell bodies in the gray matter of the CNS (specifically in the brain stem and sacral segments of the spinal cord) - craniosacral nervous system
2. Parasympathetic preganglionic neurons travel quite a distance and then terminate in an outlying parasympathetic ganglia located in the head and the thoracic and abdominal cavities close to the visceral effectors they control
3. Dendrites and cell bodies of parasympathetic post-ganglionic neurons are in these outlying ganglia and have fairly short axons extending to nearby effectors
4. Each parasympathetic preganglionic neuron synopsis with post-ganglionic neurons to only one effector
86
Describe the function of the parasympathetic nervous system
1. Dominates control of many visceral effectors (organs) under normal everyday conditions
2. Usually involves response by only one organ
3. Rest and digest - rest equals repair and rejuvenate
4. Decreases stress response - slows down body functions to conserve energy for digestion, rest, and repair
87
Describe autonomic neurotransmitters
1. The fibers (axons) of each division of the autonomic nervous system (ie the sympathetic and parasympathetic) are classified according to the type of neurotransmitters released at the synapses. There are two types of fibers - cholinergic fibers and adrenergic fibers
2. Since each division of the ANS signals its effectors with different neurotransmitters, the effector can tell which division is stimulating it and will respond accordingly - acetylcholine from the parasympathetic nervous system slows the heart; noradrenaline from the sympathetic nervous system speeds up the heart
88
Describe cholinergic fibers
1. Preganglionic axons of parasympathetic system
2. Preganglionic axons of sympathetic system
3. Postganglionic axons of parasympathetic system
4. Release acetylcholine (acetyl**choline** - **choline**rgic)
89
Describe adrenergic fibers
1. Axons of sympathetic post-ganglionic neurons
2. Releases nor adrenaline (nor**adren**aline - **adren**ergic)
90
Provide an overview of the autonomic nervous system
1. Regulates the body's automatic functions in ways that maintain or quickly restore homeostasis - to accomplish this, many visceral effectors are doubly innervated by this divisions of the ANS so they can be influenced in opposite ways
2. It is not independent from other parts of the nervous system. Dendrites and cell bodies of preganglionic neurons are located in the CNS and are continuously influenced by impulses from neurons located above them (e.g. neurons located in the hypothalamus)
3. It is affected by emotions. Emotions can produce significant and widespread changes in the automatic functions of our body eidot g dot digestion, heart rate, breathing
4. Stress / fear / anger turns on the sympathetic nervous system; happiness / calmness etc stimulates the parasympathetic nervous system
