Download ANPS 019 Black 12-05

ANPS 019
December 5, 2011
AUTONOMIC NERVOUS SYSTEM HYPOTHALAMUS
Chapter 14: 464 -467
Chapter 16: 571 – 531
Why do we need somatic and autonomic nervous systems?
How do the somatic and autonomic nervous systems differ?
How do the sympathetic and parasympathetic nervous systems differ?
How does the hypothalamus control homeostasis?
SOMATIC NERVOUS SYSTEM
Under conscious control
Conscious cortical control of motor activity
Myelinated innervation of skeletal muscles
No synapses outside of CNS – innervation of lower motor neurons (LMN)
Active only when stimulated
Acetylcholine excitatory input to target
AUTONOMIC TERMINOLOGY
Preganglionic neurons – visceral motor neurons located in brainstem and spinal cord, synapse in
autonomic ganglion, use acetylcholine
Axons of ganglionic neurons are called postganglionic axons
-begin at autonomic ganglia
Innervate visceral effectors:
-cardiac muscle
-smooth muscle
-glands
-adipose tissues
AUTONOMIC NERVOUS SYSTEM
Involuntary control of visceral function
Unmyelinated innervation of smooth and cardiac muscle, glands, and internal organs
One synapse in PNS within ganglion
Excitatory and inhibitory modulation of intrinsic target activity
-these are always in balance
Utilizes multiple neurotransmitters and receptors
HOW DO THE SOMATIC AND AUTONOMIC NERVOUS SYSTEMS DIFFER?
Somatic:
Conscious control
One neuron
One neurotransmitter (Ach)
Myelinated axon innervates effector
Innervate skeletal muscle
Only active when stimulated
Autonomic:
Involuntary
Two neurons
Two neurotransmitters (ACH & NE)
Unmyelinated axon innervates effector
Innervates viscera
Always active, modulate activity
Sympathetic vs. parasympathetic nervous system
-have to constantly be in balance
SYMPATHETIC NERVOUS SYSTEM
“Fight or flight”
Readies the body for crisis
Increase in sympathetic activity:
-stimulates tissue metabolism
-increase alertness
Preganglionic neurons are located in thoracic and lumbar spinal cord (T1-L#)
Preganglionic axons are short since the sympathetic ganglia are located close to spinal cord, but are
highly branched to innervate many targets
Postganglionic axons are very long
PARASYMPATHETIC NERVOUS SYSTEM
“REST AND DIGEST”
Stimulates visceral activity
Conserves energy and promotes sedentary activities
Preganglionic neurons located in brainstem and sacral spinal cord
Preganglionic axons are long since parasympathetic ganglia are located close to target organ and branch
very little to give finer control
Postganglionic axons are short
CN III
CN VII & CN IX salivary gland
CN X slows HR
-slows innervation
ENTERIC NERVOUS SYSTEM
Third division of autonomic NS
Contains same neurotransmitters as found in the brain
Allows from complex visceral reflexes to be coordinated locally
AUTONOMIC INTEGRATION
Medulla Oblongata:
-contains nuclei involved in:
Salvation
Swallowing
Digestive secretions
Peristalsis
Urinary function
-Regulated by hypothalamus
Hypothalamus
Interacts with all other potions of brain
Command center for homeostatic control
THE HYPOTHALAMUS REGULATES ALL AUTONOMIC FUNCTIONS
HOMEOSTASIS
-part of the diencephalon
--lies below thalamus
EXTERNAL STRUCTURES OF HYPOTHALAMUS
Mammillary bodies:
-process olfactory and other sensory information
-control reflexive eating movements
Infundibulum
-connects hypothalamus to pituitary gland
The hypothalamus is made of many small nuclei (neuron clusters)
Each individual nucleus has a unique function
THE HYPOTHALAMUS REGUALTES THE ENDOCRINE SYSTEM VIA THE PITUITARY
The hypothalamus regulates circadian daily rhythms
Clock communicates with pineal gland
Biologic clock is the suprachiasmatic nucleus
Regulation of pineal gland (melatonin)
THE HYPOTHALAMUS REGULATES WATER BALANCE
Regulates kidney function (retain water)
Supraoptic nucleus secretes antidiuretic hormone
Damage to supraoptic nucleus results in diabetes insipidus = pee more + drink more
“Thirst center”
-stimulates drinking behavior
The hypothalamus regulates food intake
“Satiety center” regulates fullness, suppresses eating behavior
“Feeding center” stimulates food consumption
Responds to peripheral signals:
Leptin from fat cells – inhibit feeding
Ghrelin from stomach – stimulate feeding
-Insulin from pancreas – inhibit feeding
Genetics contribute to obesity
Also environmental factors
The hypothalamus regulates body temperature
Preoptic area of hypothalamus its he site of body’s “thermostat”
Initiates sweating (to reduce body heat)
Initiates shivering (to increase body heat)
Thermoregulatory sweating is regulated by hypothalamus
Emotional sweating is related to limbic system
The hypothalamus controls the ANS
Hypothalamic neurons send axons down the brainstem and spinal cord to synapse in areas controlling:
Cardiovascular function (heart rate, blood pressure)
Respiration
Digestion
Reproductive activity
The hypothalamus regulates many behaviors via its interaction with the limbic system