Ch. 16 The Autonomic Nervous System and Higher-Order Functions Flashcards
(131 cards)
1
Q
The somatic nervous system operates under ______ control
A
conscious control
1
Q
What is rarely affected by the somatic nervous system?
A
long-term survival
2
Q
What type of muscles does the somatic nervous system control?
A
skeletal muscles
3
Q
The autonomic nervous system operates ______
A
without conscious instruction
4
Q
What type of effectors does the autonomic nervous system control?
A
visceral effectors
5
Q
What does the autonomic nervous system coordinate?
A
system functions:
-cardiovascular
-respiratory
-digestive
-urinary
-reproductive
6
Q
What type of neurons do the somatic nervous system include?
A
both somatic and motor neurons
7
Q
Sensory neurons are related to?
A
-touch,
-pain,
-temperature,
-proprioception (sense of self-position),
-sight,
-hearing,
-taste,
-smell,
-equilibrium
8
Q
What do motor neurons innervate?
A
skeletal muscle
9
Q
Where does the autonomic nervous system receive input from?
A
sensory receptors located in organs, blood vessels, muscles, and the nervous system
10
Q
What does the ANS regulate the activity of?
A
-smooth muscle,
-cardiac muscle,
-adipose tissue,
-certain glands
11
Q
What is the ANS regulated by?
A
centers in the brain:
-hypothalamus
-medulla oblongata
12
Q
Integrative centers
A
for autonomic activity in the hypothalamus
-neurons comparable to upper motor neurons in SNS
13
Q
Visceral motor neurons
A
preganglionic neurons in the brain stem and spinal cord
14
Q
Preganglionic fibers
A
-axons of preganglionic neurons
-leave CNS and synapse on ganglionic neurons
15
Q
Autonomic ganglia
A
-contain many ganglionic neurons
-two kinds: sympathetic and parasympathetic
16
Q
What do ganglionic neurons innervate?
A
visceral effectors:
-cardiac muscle,
-smooth muscle,
-glands,
-adipose tissue
17
Q
Postganglionic fibers
A
axons of ganglionic neurons
18
Q
Divisions of the ANS
A
sympathetic and parasympathetic
19
Q
What increases with the sympathetic division of the ANS?
A
increases:
-alertness,
-metabolic rate, and
-muscular abilities
20
Q
What increases with the parasympathetic division of the ANS?
A
digestion
21
Q
When does the sympathetic division of the ANS kick in?
A
during exertion, stress, or emergency
22
Q
What is the sympathetic division referred to as?
A
“fight or flight”
23
Q
When does the parasympathetic division of the ANS kick in?
A
during resting conditions
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What is the parasympathetic division referred to as?
"rest and digest"
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Why is the sympathetic division "fight or flight"?
its stimulation leads to increased alertness and metabolism to be ready for an emergency
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Why is the parasympathetic division referred to as "rest and digest"?
its stimulation slow down most body activity
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Sensory input of SNS
from somatic senses and special senses
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Control of motor output of SNS
voluntary control from cerebral cortex with contributions from basal ganglia, cerebellum, brain stem, and spinal cord
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Motor neuron pathway of the SNS
one-neuron pathway: somatic motor neurons extending from CNS synapse directly with effector
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Neurotransmitters and hormones of SNS
acetylcholine (ACh)
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Effectors of SNS
skeletal muscle
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Responses of SNS
contraction of skeletal muscle
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Sensory input of ANS
mainly from interoceptors; some from somatic senses and special senses
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Control of motor output of ANS
involuntary control from the hypothalamus, limbic system, brain stem, and spinal cord; limited control from cerebral cortex
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Motor neuron pathway of ANS
usually two-neuron pathway:
-preganglionic neurons extending from CNS synapse with postganglionic neurons in autonomic ganglion
-postganglionic neurons extending from ganglion synapse with visceral effector
-preganglionic neurons may extend from CNS to synapse with chromaffin cells of adrenal medullae
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Neurotransmitters and hormones of ANS
-all sympathetic and parasympathetic preganglionic neurons release ACh
-most sympathetic postganglionic neurons release norepinephrine (NE); those to sweat glands release ACh
-all parasympathetic postganglionic neurons release ACh
-Chromaffin cells of adrenal medullae release epinephrine and NE
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Effectors of ANS
smooth muscle, cardiac muscle, and glands
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Responses of ANS
-contraction or relaxation of smooth muscle
-increased or decreased rate and force of contraction of cardiac muscle
-increased or decreased secretions of glands
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What two motor neurons do each division of the ANS have?
preganglionic and postganglionic
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In the sympathetic division, where are the cell bodies of preganglionic neurons?
in the lateral horns of the gray matter in the 12 thoracic and first 2 or 3 lumbar segments
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In the parasympathetic division, where are the cell bodies of preganglionic neurons?
the nuclei of four cranial nerves (III, VII, IX, and X) in the brain stem and in the lateral gray matter of sacral segments 2-4 of the spinal cord
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Based on the neurotransmitter they produce and release, what are autonomic neurons considered?
cholinergic or adrenergic
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Cholinergic neurons release what neurotransmitter?
acetylcholine
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Adrenergic neurons release what neurotransmitter?
norepinephrine (noradrenalin)
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Cholinergic receptors include:
nicotinic and muscarinic receptors
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Major locations of cholinergic receptors
integral proteins in postsynaptic plasma membranes
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Major locations of nicotinic receptors
-Plasma membrane of postganglionic sympathetic and parasympathetic neurons
-Chromaffin cells of adrenal medullae
-Sarcolemma of skeletal muscle fibers
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Major locations of muscarinic receptors
-Effectors innervated by parasympathetic postganglionic neurons
-Sweat glands innervated by cholinergic sympathetic postganglionic neurons
-Skeletal muscle blood vessels innervated by cholinergic sympathetic postganglionic neurons
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Effects of nicotinic receptor activation
-excitation-->impulses in postganglionic neurons
-epinephrine and norepinephrine secretion
-excitation-->contraction
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Effects of muscarinic receptor activation
-in some, excitation; in others, inhibition
-increased sweating
-inhibition-->relaxation-->vasodilation
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Major locations of adrenergic receptors
-integral proteins in postsynaptic plasma membranes; activated by the neurotransmitter norepinephrine and the hormones norepinephrine and epinephrine
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Major locations of a1 receptor
-smooth muscle fibers in blood vessels that serve salivary glands, skin, mucosal membranes, kidneys, and abdominal viscera
-radial muscle in iris of eye
-sphincter muscles of stomach and urinary bladder
-salivary gland cells
-sweat glands on palms and soles
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Major locations of a2 receptor
-smooth muscle fibers in some blood vessels
-cells of pancreatic islets that secrete the hormone insulin
-pancreatic acinar cells
-platelets in blood
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Major locations of B1 receptor
-cardiac muscle fibers
-juxtaglomerular cells of kidneys
-posterior pituitary
-adipose cells
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Major locations of B2 receptor
-smooth muscle in walls of airways; in blood vessels that serve the heart, skeletal muscle, adipose tissue, and liver; and in walls of visceral organs, such as urinary bladder
-ciliary muscle in eye
-hepatocytes in liver
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Major locations of B3 receptor
brown adipose tissue
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Effects of a1 receptor activation
-excitation-->contraction, which causes vasoconstriction, dilation of pupil, and closing of sphincters
-secretion of K+ and water
-increased sweating
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Effects of a2 receptor activation
-inhibition-->relaxation-->vasodilation
-decreased insulin secretion
-inhibition of digestive enzyme secretion
-aggregation to form platelet plug
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Effects of B1 receptor activation
-excitation-->increased force and rate of contraction
-renin secretion
-antidiuretic hormone (ADH) secretion
-breakdown of triglycerides-->release of fatty acids into blood
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Effects of B2 receptor activation
-inhibtion-->relaxation, which causes dilation of airways, vasodilation, and relaxation of organ walls
-inhibition-->relaxation
-glycogenolysis (breakdown of glycogen into glucose)
-thermogenesis (heat production)
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Alpha-1 (a1)
-more common type of alpha receptor
-releases intracellular calcium ions from reserves in the endoplasmic reticulum
-has an excitatory effect on the target cell
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Alpha-2 (a2)
-lowers cAMP levels in cytoplasm
-has inhibitory effect on the cell
-helps coordinate sympathetic and parasympathetic activities
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Beta (B) receptors
-affect membranes in many organs (skeletal muscles, lungs, heart, and liver)
-trigger metabolic changes in target cell
-stimulation increases intracellular cAMP levels
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Beta-1 (B1)
increases metabolic activity
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Beta-2 (B2)
triggers relaxation of smooth muscles along respiratory tract
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Beta-3 (B3)
leads to lipolysis, the breakdown of triglycerides in adipocytes
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The sympathetic and parasympathetic divisions of the ANS are ________ to each other
antagonistic
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Parasympathetic activation
-centers on relaxation, food processing, and energy absorption
-localized effects, last a few seconds at most
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Major effects of parasympathetic division
-constriction of pupils to restrict the amount of light that enters the eyes
-secretion by digestive glands (salivary, gastric, duodenal, and intestinal glands)
-secretion of hormones
-changes in blood flow and glandular activity
-increase in smooth muscle activity
-stimulation and coordination of defecation
-contraction of the urinary bladder during urination
-constriction of the respiratory passageways
-reduction in heart rate and in the force of contraction
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Neuromuscular and Neuroglandular Junctions
-release ACh
-small, with narrow synaptic clefts
-effects of stimulation are short lived
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Nicotinic receptors
-on surfaces of ganglion cells
-exposure to ACh causes excitation of ganglionic neurons or muscle fiber
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Muscarinic receptors
-at cholinergic neuromuscular or neuroglandular junctions
-at few cholinergic junctions
-G proteins
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What does nicotine bind to
nicotinic receptors
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What does nicotine target?
autonomic ganglia and skeletal neuromuscular junctions
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What does muscarine bind to?
muscarine receptors
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What does muscarine target?
parasympathetic neuromuscular or neuroglandular junctions
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Distribution of SNS
wide regions of body
-skin
-sweat glands
-arrector pili muscles of hair follicles
-adipose tissue
-smooth muscle of blood vessels
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Location of preganglionic neuron cell bodies and site of outflow of SNS
lateral gray horns of spinal cord segments T1-L2
79
Associated ganglia of SNS
sympathetic trunk ganglia and prevertebral ganglia
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Ganglia locations of SNS
close to CNS and distant from visceral effectors
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Axon length and divergence of SNS
preganglionic neurons with short axons synapse with many postganglionic neurons with long axons that pass to many visceral effector
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White and gray rami communicantes in SNS
both present:
-white rami contain myelinated preganglionic axons;
-gray rami contain unmyelinated postganglionic axons
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Neurotransmitters of SNS
ACh and NE
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Physiological effects of SNS
fight-or-flight responses
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Distribution of the PSNS
limited mainly to head and to viscera thorax, abdomen, and pelvis; some blood vessels
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Location of preganglionic neuron cell bodies and site of outflow PSNS
Nuclei of cranial nerves III, VII, IX, and X and lateral gray matter of spinal cord segments S2-S4
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Associated ganglia of PSNS
terminal ganglia
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Ganglia locations of PSNS
typically near or within wall of visceral effectors
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Axon length and divergence of PSNS
preganglionic neurons with long axons usually synapse with 4-5 postganglionic neurons with short axons that pass to a single visceral effector
90
White and gray rami communicates PSNS
neither present
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Neurotransmitters of PSNS
ACh
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Physiological effects of the PSNS
rest-and-digest activities
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Dual innervation of sympathetic division
-widespread impact
-reaches organs and tissues throughout body
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Dual innervation of parasympathetic division
innervates only specific visceral structures
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Anatomy of Dual Innervation
-parasympathetic postganglionic fibers accompany cranial nerves to peripheral destinations
-sympathetic innervation reaches same structures
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Visceral Reflexes
-provide automatic motor responses
-can be modified, facilitates, or inhibited by higher centers, especially hypthalamus
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Long reflexes
-autonomic equivalents of polysynaptic reflexes
-visceral sensory neurons deliver information to CNS along dorsal roots of spinal nerves
-ANS carries motor commands to visceral effectors
-Coordinate activities of entire organ
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Short reflexes
-Bypass CNS
-Involve sensory neurons and interneurons located within autonomic ganglia
-interneurons synapse on ganglionic neurons
-motor commands distributed by postganglionic fibers
-control simple motor responses with localized effects
-one small part of target organ
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What are controlled by autonomic reflexes?
-heart rate
-force of ventricular contraction
-blood pressure
-blood vessel diameter
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What is the reflex arc composed of?
-receptor
-sensory neuron
-integrating center
-motor neurons
-an effector
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What monitors all other systems?
the nervous system
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What 3 characteristics do higher-order functions share?
1. require the cerebral cortex
2. involve conscious and unconscious information processing
3. are not part of programmed "wiring" of brain
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Fact memories
specific bits of information
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Skilled memories
-learned motor behaviors
-incorporated at unconscious level with repetition
-programmed behaviors stored in appropriate area of brain stem
-complex skill memories are stored and involve motor patterns in the basal nuclei, cerebral cortex and cerebellum
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Short-term memories
-information that can be recalled immediately
-contain small bits of information
-primary
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Memory consolidation
conversion from short-term to long-term memory
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2 types of long-term memory
1. secondary memories fade and require effort to recall
2. tertiary memories are with you for life
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What are the brain regions involved with memory consolidation and access?
-amygdaloid body and hippocampus
-nucleus basalis
-cerebral cortex
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Facilitation at Synapses
-neural circuit repeatedly activated
-synaptic terminals begin continuously releasing neurotransmitter
-neurotransmitter binds to receptors on postsynaptic membrane
-produces graded depolarization
-brings membrane closer to threshold
-facilitation results affects all neurons in circuit
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What is deep sleep called?
slow wave or non-REM (NREM) sleep
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What declines during deep sleep?
heart rate, blood pressure, respiratory rate, and energy utilization up to 30%
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Rapid Eye Movement (REM) sleep
-active dreaming occurs
-changes in blood pressure and respiratory rate
-less receptive to outside stimuli
-muscle tone decreases
-intense inhibition of somatic motor neurons
-eyes move rapidly during dreams
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Nighttime sleep pattern
-alternates between levels
-begins in deep sleep
-REM periods average 5 minutes in length, increase to 20 min.
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What increases during sleep?
Protein synthesis in neurons
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Arousal and the reticular activating system (RAS)
-awakening from sleep
-the function of the reticular formation
-extensive interconnections with sensory, motor, integrative nuclei, and pathways along the brain stem
-determined by complex interactions between reticular formation and cerebral cortex
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Reticular Activating System (RAS)
-important brain stem component
-diffuse network in reticular formation
-from medulla oblongata to midbrain
-stimulation of RAS produces widespread activation of cerebral cortex
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Brain chemistry
changes in normal balance between two or more neurotransmitters can profoundly affect brain function
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What is Huntington's Disease?
destruction of ACh-secreting and GABA-secreting neurons in basal nuclei
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Symptoms of Huntington's disease
-difficulty controlling movements
-intellectual abilities gradually decline
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Lysergic Acid Diethylamide (LSD)
a powerful hallucinogenic drug
-activates serotonin receptors in brain stem, hypothalamus, and limbic system
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What is Parkinson's Disease?
inadequate dopamine production causing motor problems
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Common age-related anatomical changes in the nervous system
-reduction in brain size and weight
-reduction in the number of neurons
-decrease in blood flow to the brain
-changes in the synaptic organization of the brain
-intracellular and extracellular changes in CNS neurons
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Reduction in brain size and weight
-decrease in volume of cerebral cortex
-narrower gyri and wider sulci
-larger subarachnoid space
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Reduction in number of neurons
-brain shrinkage linked to loss of cortical neurons
-no neuronal loss in brain stem nuclei
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Decrease in blood flow to the brain
Arteriosclerosis
-fatty deposits in walls of blood vessels
-reduces blood flow through artery
Cerebrovascular accident (CVA), or stroke
-may damage surrounding neural tissue
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Changes in synaptic organization of brain
-number of dendritic branches, spines, and interconnections decreases
-synaptic connections lost
-rate of neurotransmitter production declines
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Sensory system effects of agining
-hearing, balance, vision, smell, and taste become less acute
-reaction times slowed
-reflexes weaken or disappear
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Motor control effects of agining
-precision decreases
-takes longer to perform
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Senility
also called senile dementia
degenerative changes
-memory loss
-lose the ability to store new memories
-emotional disturbances
-Alzheimer's disease is the most common type
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