Chapter 16 Outline (10th) PDF

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Anatomy and Physiology I Chapter 16 Outline: The Autonomic Nervous System and HigherOrder Functions I.

Organization of the Autonomic Nervous System a. Integrative center located in hypothalmus b. Preganglionic Neurons i. Equivalent to upper motor neuron of somatic nervous system

ii. Located in brain stem and spinal cord iii. The axons of preganglionic fibers leave the CNS and synapse on ganglionic neurons (these axons are called preganglionic fibers) c. Autonomic ganglia i. Contain many Ganglionic Neurons d. Ganglionic neurons i. Equivalent to lower motor neuron of somatic nervous system ii. Innervate the visceral effectors (such as: cardiac muscle, smooth muscle, glands, and adipose tissue) iii. The axons of ganglionic neurons are called postganglionic fibers e. 2 Divisions of the Autonomic Nervous System i. ii.

Sympathetic “fight or flight”

Parasympathetic “rest and digest”

Preganglioni c fibers synapse: In ganglia near spinal cord

Preganglioni c fibers

Postganglioni c fibers

Location

Short

Long (except at adrenal medullae)

In ganglia close to (or within) target organs

Long

Short

Thoraco- 1-sympathetic lumbar chain T1-L2 2-collateral ganglia 3-adrenal medullae Cranio1-Terminal – near sacral target organ 2-Intramural – embedded in tissues of target organ

Ganglionic neurons

*Enteric Nervous System – 3rd division of the ANS, extensive network in digestive tract walls II. Sympathetic Nervous System 1

a. 7 responses to INCREASED Sympathetic activity i. Heightened mental alertness ii. Increased metabolic rate iii. REDUCED digestive and urinary functions iv. Energy reserves activated v. Increased respiratory rate and respiratory passageways dilate vi. Increased heart rate and blood pressure vii. Sweat glands activated b. Ganglionic Neurons i. Sympathetic Chain Ganglia 1. Located on both sides of vertebral column 2. “string of pearls” ii. Collateral Ganglia 1. Located to vertebral bodies 2. Contain ganglionic neurons that innervate tissues and organs in abdominopelvic cavity iii. Adrenal Medullae (suprarenal medullae) 1. Very short postganglionic axons 2. When stimulated – release neurotransmitters into the bloodstream (not at a synapse) a. These neurotransmitters function as hormones to affect target cells throughout the body b. As a result the effects last longer 3. Neuroendocrine cells secrete 2 different neurotransmitters: a. Epinephrine b. Norepinephrine 4. Receptors for NE and E a. Alpha receptors b. Beta receptors i. Blocking the beta receptors (beta-blocking drugs) would decrease or prevent sympathetic stimulation of these tissues therefore decreasing HR and lower blood pressure III.

Parasympathetic Nervous System a. 5 responses to INCREASED Parasympathetic activity i. decreased metabolic rate ii. decreased heart rate and blood pressure iii. increased secretion by salivary and digestive glands iv. increased motility and blood flow in digestive tract v. urination and defecation stimulation b. Vagus Nerve (N X)

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i. Provides the preganglionic parasympathetic innervation to structures in: 1. Neck 2. Thoracic and abdominopelvic cavities as distant as a distal portion of the large intestine 3. Provides 75% of all parasympathetic outflow!! c. More major effects of Parasympathetic Division i. Constriction of pupils ii. Secretion by digestive glands iii. Secretion of hormones iv. Changes in blood flow and glandular activity v. Increase in smooth muscle activity along the digestive tract d. Parasympathetic Neurons release Ach i. 2 receptors 1. Nicotinic a. Exposure to Ach causes b. Nicotine:

2. Muscarinic a. Can be excitatory or inhibitory b. Effects are longer lasting than Nicotinic receptors c. Muscarine:

IV.

Dual Innervation a. Autonomic Tone i. If nerve is INACTIVE under normal conditions, it can only activity ii. If nerve maintains background level of activity, it can or activity b. Heart example:

V.

Higher-Order Functions  Require the Cerebral Cortex  Involve conscious and unconscious information processing  Are not part of programmed “wiring” of brain (can adjust over time) a. Memory i. Fact memories – specific bits of info ii. Skill memories – learned motor behaviors

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iii. Short-term memories – info that can be recalled immediately 1. PRIMARY memories iv. Long-term memories – 1. Memory consolidation is the conversion from to long term memory.

short term

2. SECONDARY memories 3. TERTIARY memories –

v. Brain Regions involved in Memory consolidation and access 1. Amygdaloid body and hippocampus a. Essential for memory consolidation b. If damaged…inability to convert short-term memories to new long-term memories 2. Nucleus basalis a. Damage changes emotional states, memory, and intellectual functions 3. Cerebral cortex

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a. Stores b. Conscious motor and sensory memories referred to association areas i. Occipital and temporal lobes 1. Special portions are crucial to memories of faces, voices, and words 2. Grandmother cells b. States of consciousness i. Deep sleep – ii. Rapid eye movement (REM) sleep – iii. Arousal and the reticular activating system (RAS) 1. RAS a. When activated, this ends sleep! VI.

Effects of aging on the nervous system a. 85% of people over age 65 have changes in mental performance and CNS function b. Common age related anatomical changes i. Reduction in brain size and weight ii. Reduction in number of neurons iii. Decrease in blood flow to brain 1. Arteriosclerosis – 2. CVA (stroke) iv. Changes in synaptic organization of brain v. Intracellular and extracellular changes in CNS neurons c. Incapacitation i. 85% of elderly population develops changes that do NOT interfere with abilities ii. Senility – senile dementia 1. Degenerative changes a. Memory loss b. Emotional disturbance c. Lose ability to store new memories d. Alzheimer’s commons 2. Alzheimer’s Disease a. Symptoms usually appear between the age of 50-60 b. Genetic factors

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