ch 11 Flashcards
Nervous System Content
Consists of:
Brain
Spinal Cord
Nerves
Endocrine System
Employs chemical messengers called hormones to communicate with cells
Nervous System
Uses electrical signals to transmit messages at lightning speed
What roles does the nervous system have?
-Sensing
-Integrating
-Responding
Nervous system’s two main divisions?
-Central Nervous System
-Peripheral Nervous System
Central Nervous System
Consists of:
Brain
Spinal Cord
Peripheral Nervous System
The vast network of nerves throughout the body
-sensory (afferent) division
-Motor (efferent) division
Afferent
Sensory
Efferent
Motor
Somatic Sensory
Carries signals from skin, bones, joints, and muscles
Visceral Sensory
Carries signals from viscera of heart, lungs, stomach, and bladder
Somatic Motor
Allows voluntary movements of skeletal muscles
Autonomic Motor
Provides “automatic” activities like control of blood pressure or heart rate
Sympathetic Division
Arouses the body for action
Parasympathetic Division
Has a calming effect
What are the two types of cells that make up the nervous system?
Neurons and neuroglia
Glial Cells
Another name for Neuroglia
These are the supportive cells of the nervous system.
About how many glial cells are there for each neuron?
50 glial cells for each neuron
What are the 5 major types of glial cells?
Oligodendrocytes
Ependymal Cells
Microglia
Astrocytes
Schwann Cells
Oligodendrocytes
Form myelin sheath in the brain and spinal cord; speed signal conduction
Ependymal Cells
Line spinal cord and cavities of the brain; some secrete cerebrospinal fluid; whereas others have cilia that aid in fluid circulation
Microglia
Perform phagocytosis, engulfing microorganisms and cellular debris
Astrocytes
Extend through brain tissue; nourish neurons, help form blood-brain barrier, attach neurons to blood vessels, provide structural support
Schwann Cells
Form myelin sheath around nerves in PNS; form neurilemma
Neurons
Handle the nervous system’s role of communication
What are the three classes for neurons?
Sensory
Interneurons
Motor
Sensory Neurons
Detect stimuli, like touch pressure heat cold or chemicals, and then transmit information about the stimuli to the CNS
Interneurons
(found only in CNS)
Connect the incoming sensory pathways with the outgoing motor pathways. Besides receiving, processing, and storing information, the connections made by these neurons make each of us unique in how we think feel and act
Motor Neurons
Relay messages from the brain (which the brain emits in response to stimuli) to the muscle or gland cells
Types of neurons
Multipolar
Bipolar
Unipolar
Multipolar
Bipolar
Unipolar
Three basic structures in a neuron?
Cell Body
Axon
Dendrite
Cell Body
Also called soma
Its the control center of the neuron and contains the nucleus
Dendrites
Look like bare branches of a tree, recieve signals from other neurons and conduct the information to the cell body.
Axon
Myelin Sheath
Nodes of Ranvier
Synaptic Knob
What is the longest axon in the body?
The sciatic nerve
Cauda Equina
Extends from the end of the spinal cord, is a bundle of nerve roots that looks like a horse tail
Grey Matter
Appears grey because of lack of myelin
Contains mostly the cells bodies of motor neurons and interneurons. H-shaped mass is divided into two sets of horns, Posterior horns (dorsal) and Ventral Horns (anterior)
White Matter
Appears white because of its abundance of myelin. Contains bundles of axons (called tracts) that carry impulses from one part of the nervous system to another.
Epidural Space
Small space between that lies between the outer covering of the spinal cord and the vertebrae, it contains cushioning layer of fat as well as blood vessels and connective tissue.
Central Canal
A minute opening that carries cerebrospinal fluid through the spinal cord
Dorsal Nerve Root
Contains fibers that carry sensory information into the spinal cord. It enters the dorsal horn of the spinal cord.
Ganglion
Cell bodies of the dorsal neurons are clustered in a knot like structure
Spinal Nerve
A single nerve resulting from the fusion of the dorsal and ventral nerve roots. The nerve contains both sensory and motor fibers. It is called a mixed nerve.
Ventral Nerve Root
Exit from the ventral horn to carry motor information out of the spinal cord
Pia Mater
The innermost layer, transparent membrane that clings to the outer surface of the brain and spinal cord. It also contains blood vessels.
Subarachnoid Space
Lies between the arachnoid mater and the pia mater. It is filled with cerebrospinal fluid.
Arachnoid Mater
A delicate layer resembling a cobweb, lies between dura mater and the pia mater
Dura Mater
Tough outer layer
How many pairs of spinal nerves?
31 pairs
Cervical Plexus
Contains nerves that supply the muscles and skin of the neck,tops of shoulders, and part of the head.
Phrenic Nerve
Stimulates the diaphragm for breathing
Brachial Plexus
Innervates the lower part of the shoulder and the arm.
Axillary Nerve
Passes close to the armpit which makes it susceptible to damage from the use of crutches
What other notable nerves are included in Brachial Plexus?
Radial Nerve
Ulnar Nerve
Median Nerve
Lumbar Plexus
Derived from the fibers of the first four lumbar vertebrae, supplies the thigh and leg. (Femoral nerve is here)
Sacral Plexus
Formed from fibers from nerves L4 L5 and S1 through S4. Sciatic nerve is located in here and is the largest nerve in the body
Dermatome
Each spinal nerve innervates a specific area of the skin
Reflex Arc
Reflexes employ a neural circuit which bypasses regions of the brain where conscious decisions are made.
Somatic Reflexes
Involve the contraction of a skeletal muscle after being stimulated by a somatic motor neuron.
Babinski Sign
Normal in infants up to 18m, in adults this happens if there is damage to primary motor cortex or corticospinal tract.
Big toe will dorsiflex and smaller toes will fan outward.
Cerebrum
Largest portion of the brain.
Gyri / Gyrus
Thick ridges on the surface of the cerebrum
Sulci/ sulcus
Shallow grooves on the surface of the cerebrum that divide the gyri - deep sulci are called fissures
Diencephalon
Sits between the cerebrum and the midbrain
Cerebellum
Second largest region of the brain. Contains more neurons than the rest of the brain combined.
Brain stem
Makes up the rest of the brain
Consists of these structures:
- Midbrain
- Pons
- Medulla Oblongata
Decussation
When tracts cross over to the opposite side of the body L brain to R side body
Longitudinal Fissure
Divides the cerebrum into right and left cerebral hemispheres.
Corpus Callosum
Thick bundle of nerves that run along the bottom of the fissure and serves to connect the two hemispheres
Cortex
Gray matter covers the cerebrum and cerebellum in a layer (on outside)
Nuclei
Under the cortex is white matter that contains bundles of axons that connect one part of the brain to another (on inside of brain)
What are the Meninges of the brain?
They are Dura matter
Arachnoid mater
pia mater
Dura Mater
Consists of two layers;
Outer later is attached to the inner surface of the skull
inner layer forms the outer covering of the brain and continues as the dura mater of the spinal cord
Arachnoid Mater
The middle layer of the brain meninges
Pia Mater
Inner most layer of brain meninges, clings tightly to the surface of the brain
Dural sinuses
These sinuses collect blood that has passed through the brain and is on the way back to the heart
Subdural Space
Separates the dura from the arachnoid mater
Subarachnoid Space
Separates the arachnoid mater from the pia mater
Ventricles
Four chambers in the brain are called this
Lateral Ventricles
Two, one on left and one on right, arch through the cerebral hemispheres
Third Ventricle
Each lateral ventricle connects to this
Fourth Ventricle
This space narrows to form the central canal which extends through the spinal cord
Cerebrospinal Fluid
CSF Clear colorless fluid that fills the ventricles and central canal; also bathes the outside of the brain and spinal cord
Choroid Plexus
CSF is formed from blood here. (network of blood vessels lining the floor or wall of each ventricle)
Three centers in the Medulla Oblongata?
Cardiac Center
Vasomotor center
Respiratory Centers (two)
Brain Stem is made up of what parts?
Midbrain
Pons
Medulla Oblongata
Midbrain
Contains tracts that relay sensory and motor impulses. Also contains centers for auditory and visual reflexes as well as clusters of neurons integral to muscle control
Pons
Contains tracts that convey signals to and from different parts of the brain. Several cranial nerves arise from this area; they are 5-8
Medulla Oblongata
Attaches the brain to the spinal cord. Besides relaying sensory and motor signals between the brain and spinal cord, the medulla contains nuclei that perform functions vital to human life.
What is the function of the cardiac center?
Regulates heart rate
What is the function of the vasomotor center?
Controls blood vessel diameter which in turn affects blood pressure
What is the function of the respiratory centers?
They regulate breathing
What part of the brain has more neurons than the rest of the brain combined?
The Cerebellum
Blood-Brain Barrier
Serves to restrict what substances can pass from the bloodstream into the tissue fluid of the brain.
Diencephalon
A region deep inside the brain consisting of several structures
What are the structures in the diencephalon?
Thalamus
Hypothalamus
Thalamus
Resides on top of the brain stem, acts as a gateway for nearly every sensory impulse traveling to the cerebral cortex. The thalamus processes and filters these impulses, transmitting some, but not all to the cerebral coretex.
Hypothalamus
Small
Controls the autonomic nervous system
Contains centers responsible for hunger, thirst, and temperature regulation
Controls the pituitary gland
Involved in multiple emotional responses including fear anger pleasure and aggression
Cerebrum
Largest portion of the brain
Consists of 5 lobes
Frontal Lobe
Parietal Lobe
Temporal Lobe
Occipital Lobe
Insula
Insula
Hidden behind the lateral sulcus
Plays a role in many functions, including perception of pain, basic emotions, addiction, motor control, self-awareness, and cognitive functioning
Occipital Lobe
Concerned with analyzing and interpreting visual information
Parietal Lobe
Central Sulcus forms the anterior boundary
Concerned with receiving and interpreting bodily sensations, also governs proprioception
Frontal Lobe
Temporal Lobe
Separated front he parietal Lobe by the lateral sulcus
Governs hearing smell learning memory emotional behavior and visual recogition
White Matter (cerebrum)
The bulk of the cerebrum
Consists of myelinated nerve fibers called tracts.
Corpus Callosum
The bridge between each hemisphere - allows the brains two hemispheres to communicate with each other
Cerebral cortex
Surface of the cerebrum, Consists of a thin layer of gray matter
Basal Nuclui
Masses of gray matter
Basal Ganglia
Lie deep within the cerebrum
Limbic System
Sometimes called “the emotional brain”
The seat of emotion and learning
Formed out of two key structures:
Hippocampus
Amygdala
Hippocampus
Charged with converting short-term memory into long-term memory, making it crucial for memory and learning
Amygdala
Two almond-shamed masses of neurons, located on each side of thalamus
Deals with emotions such as anger, jealousy, and fear.
Stores and can recall emotions from past events.
Motor Association Area
Determine which movements are required to perform a specific task, then sends the appropriate signals to the pre central gyrus
Precentral Gyrus
Send impulses through the motor tracts in the brain stem and spinal cord. The impulses travel to the skeletal muscles and movement occur.
Postcentral Gyrus
The primary somatic sensory area of the brain.
Receives the impulses of heat, cold, touch from receptors all over the body
Somatic Sensory Association Area
This area allows us to pinpoint the location of pain, identify a texture, and be aware of how our limbs are positioned
Written words stimulate what?
Primary Visual Cortex
What translates written words into a form that can be spoken?
The Angular Gyrus
What is housed in the left temporal lobe and formulates the words into phrases that comply with learned grammatical rules?
Wernicke’s Area
What is located in the left frontal lobe, and plans the muscle movements required of the larynx, tongue, cheeks, and lips to form the words, and then sends the appropriate impulses to the primary motor cortex?
Broca’s Area
What sends impulses to the muscles necessary to pronounce the word?
The Primary Motor Cortex
Short term memory
Information that is stored briefly
Long Term Memory
Information that is stored for days or years.
Neuroplasticity
The ability of the brain to change its actual physical structure
Olfactory Association Area
Interprets the sense of smell
Primary gustatory complex
Handles the interpretation and sensation of taste
Visual Association Area
Interprets the information acquired through the primary visual cortex. Allows you to recognize familiar objects.
Primary Visual Cortex
Responsible for sight. Governs the recognition of size, color, light, motion, and dimension.
Auditory Association Area
Gives the ability to recognize familiar sounds, including a person’s voice or the name of a song.
Primary auditory complex
Responsible for hearing
REM
Rapid Eye Movement which is associated with active dreaming
NREM
Non-rapid eye movement
What does the left side of the brain do?
Motor control of R side of body
Sequential processing
Language
Analytical Thought
Logical
Concrete
Science and Math
What does the right side of the brain do?
Motor control of the L side of body
Simultaneous processing
“big picture”
Creativity
Emotion
Imagination
Art and Music
How many pairs of cranial nerves are there?
12 pairs
What are the 12 pairs of cranial nerves?
Olfactory
Optic
Oculomotor
Trochlear
Trigeminal
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Vagus
Accessory
Hypoglossal
Olfactory Nerve (sensory)
- Governs sense of smell
- Terminates in olfactory bulbs in the cribriform plate, just above the nasal cavity
- Impairment results in an impaired sense of smell (which may be linked to loss of taste)
To test: ask person to smell coffee or vanilla
Facial Nerve (mixed)
Sensory portion: concerned with taste
Motor portion: controls facial expression and secretion of tears and saliva
Damage causes sagging of facial muscles and a distorted sense of taste
To test: check sense of taste on anterior two-thirds of tongue, test ability to smile, frown, whistle, and raise eyebrows.
Vestibulocochlear Nerve (sensory)
Concerned with hearing and balance
Damage results in deafness, dizziness, nausea, and loss of balance
To test: hearing, balance, and ability to walk a straight line.
Vagus Nerve (mixed)
Longest and most widely distributed cranial nerve
Supplies organs in the head and neck as well as those in the thoracic and abdominal cavities
Plays key role in many heart, lung, digestive, and urinary functions
Damage causes hoarseness or loss of voice and impaired swallowing; damage to both vagus nerves can be fatal
To test: perform same tests as cranial nerve IX (glossopharyngeal)
Optic Nerve (sensory)
Concerned with vision
Links the retina to brains visual cortex
Damage causes blindness in part or all of the visual field.
To test: check visual acuity and peripheral vision
Oculomotor, Trochlear, and Abducens Nerves (mainly motor)
regulate voluntary movements of the eyelid and eyeball; oculomotor also controls pupil constriction
Damage can cause drooping eyelid, dilated pupil (oculomotor only), inability to move eye in some directions, double vision
To test: inspect size, shape, and reaction of pupils; check eye movements and ability to follow moving object
Trigeminal Nerve (two sensory and one mixed branch)
Sensory branches (ophtalmic and maxillary) sense touch, temperature, and pain on the eye, face and teeth; mixed branch (mandibular) controls chewing and detects sensations in the lower jaw
Ophthalmic branch triggers the corneal reflex: blinking in response to a touch on the eyeball.
Damage to the sensory branches causes loss of sensation in upper face, damage to mixed branch results in impaired chewing and loss of sensation in jaw
To test: Lightly touch eyeball with cotton swab to check corneal reflex; evaluate sense of touch, pain, and temperature with pin as well as hot and cold objects; evaluate ability to open mouth and move jaw side to side.
Glossopharyngeal Nerve (mixed)
Motor fibers govern tongue movements, swallowing, and gagging
Sensory fibers handle taste, touch, and temperature from tongue; also concerned with regulation of blood pressure
Damage causes impaired swallowing, choking, and bitter or sour taste
To test: test gag reflex, swallowing, and coughing; check taste on the posterior one-third of the tongue
Hypoglossal Nerve (mainly motor)
Controls tongue movements
Damage causes impaired speech and swallowing as well as deviation of tongue toward injured side
To test: check for tongue deviation when tongue is protruded
Spinal Accessory Nerve (mainly motor)
Controls movement in the head, neck, and shoulders
Damage impairs movement of the head, neck, and shoulders
To test: check ability to rotate head and shrug shoulders against resistance
Autonomic Nervous System (ANS)
Subdivision of the nervous system responsible for regulating the activites that maintain homeostasis.
Autonomously
Independently
VIsceral Motor System
Targets organs
Sends motor impulses to cardiac muscle, glands, and smooth muscle
Visceral Reflexes
Reflexes that affect organs
Visceral Reflex Arc
1) Receptors detect a change in body conditions
2) Afferent neurons transmit information about this change to the CNS
3) The brain processes this information and transmits a signal along an efferent nerve
4) The effector organ receives the message and responds
What are some of the differences between the Somatic and Autonomic Nervous Systems?
Somatic:
-Innervates skeletal muscle
-consists of one nerve fiber leading from cns to target
-secretes neurotransmitter acetylcholine
-has an excitatory effect on target cells
-operates under voluntary control
——-
Autonomic:
-Innervates glands, smooth muscle, and cardiac muscle
-consists of two nerve fibers that synapse at a ganglion before reaching target
-secretes both acetylcholine and norepinephrine as neurotransmitters
-may excite or inhibit target cells
-operates involuntarily
Somatic
-Innervates skeletal muscle
-consists of one nerve fiber leading from cns to target
-secretes neurotransmitter acetylcholine
-has an excitatory effect on target cells
-operates under voluntary control
Lack of sleep can cause:
Hypertension
Depression
Obesity
Cardiovascular Disease
Dementia
Autonomic
-Innervates glands, smooth muscle, and cardiac muscle
-consists of two nerve fibers that synapse at a ganglion before reaching target
-secretes both acetylcholine and norepinephrine as neurotransmitters
-may excite or inhibit target cells
-operates involuntarily
How many divisions are there in the ANS?
Two -
Sympathetic and Parasympathetic
Sympathetic Division
- Increases alertness
- Increases heart rate
- Dilates bronchial tubes to increase air in lungs
- Dilates blood vessels of skeletal muscles to increase blood flow
- inhibits intestinal motility
- stimulates secretion of thick salivary mucus
- stimulates sweat glands
- stimulates adrenal medulla to secrete epinephrine
- has no effect on urinary bladder or internal sphincter
Causes Fight or Flight response
Parasympathetic Division
- Has calming effect
- decreases heart rate
- constricts bronchial tubes to decrease air flow in lungs
- has no effect on blood vessels of skeletal muscles
- stimulates intestinal motility and secretion to promote digestion
- Stimulates secretion of thin salivary mucus
- has no effect on sweat glands
- has no effect on adrenal medulla
- stimulates the bladder wall to contract and the internal sphincter to relax to cause urination
- causes the resting and digesting state
Autonomic Tone
when the sympathetic and parasympathetic divisions of the ANS work at the same time
Thoracolumbar Division
Also called Sympathetic division
Adrenal Glands
Triangular shaped glands perched on the tops of each kidney
They play a role in the function of the sympathetic nervous system
Adrenal Medulla
Sympathetic preganglionic fibers pass through the outer cortex of the adrenal gland and terminate in the center.
What hormones does the adrenal medulla secrete when stimulated?
Epinephrine and small amounts of norepinephrine
Craniosacral Division
Another name for the parasympathetic division
What are the two different neurotransmitters that the ANS employs?
Acetylcholine and Norepinephrine
What are fibers that secrete acetylcholine called?
Cholinergic Fibers
What are fibers that secrete norepinephrine (sometimes called noradrenaline)?
Adrenergic Fibers
Cholinergic Fibers
- Include the preganglionic fibers of both the sympathetic and parasympathetic divisions
- include the post ganglionic fibers of the parasympathetic division
- Secrete acetylcholine
Adrenergic Fibers
- include most. (But not all) of the postganglionic fibers of the sympathetic division
- secrete norepinephrine
What receptors are there for acetylcholine?
Nicotinic and Muscarinic receptors
Nicotinic Receptors
- These receptors occur within the ganglia of the ANS, in the adrenal medulla, and in the neuromuscular junction
- all cells with Nicotinic receptors are excited by ACh
Muscarinic Receptors
- these receptors occur on the glands, smooth muscle, and cardiac muscle cells of the organs innervated by Cholinergic fibers
- cells with muscarinic receptors exhibit a variable response to ACh: some are excited and some are inhibited
- this variable response allows ACh to stimulate intestinal smooth muscle while inhibiting cardiac muscle
Adrenergic Receptors
Two basic types of receptors:
Alpha Adrenergic receptors
Beta Adrenergic receptors
What cells are excited by NE
Cells with Alpha Adrenergic receptors
What cells are inhibited by NE
Cells with beta Adrenergic receptors
Action Potential
Nerve Impulse
Afferent Neuron
Sensory nerve that carries impulses toward the central nervous system
Corticospinal Tracts
Spinal tracts that are responsible for fine movements of hands, fingers, feet, and toes on the opposite side of the body; also called pyramidal tracts
Spinothalamic Tract
Spinal tract that relays sensations of temperature, pressure, pain, and touch
Spinocerebellar Tract
Spinal tract responsible for proprioception
Salatory Conduction
Conduction of nerve impulses along myelinated axons from one node of Ranvier to the next
