The Nervous System

Define automatic nervous system

Component of peripheral nervous system that regulated involuntary physiological processes, has sympathetic and parasympathetic divisions

Function of hypothalamus

Controls ANS and responsible for basic survival strategies through ANS and endocrine system

Specific functions of hypothalamus

Cardiovascular regulation, body temp regulation, gastrointestinal and feeding regulation, body water regulation, thirst control, control of excretion of water into urine, regulation of uterine contraction/milk production, anterior pituitary control

Structures of ANS

Preganglionic and post ganglionic neurons

Ganglion is a bundle of nerve cell bodies that are the location of synapses between pre and post ganglionic neurons

Neurons in sympathetic nervous system

Thoracolumbar region of spinal cord, short pre and long post ganglionic, ganglion located close to spinal cord

Neurons in parasympathetic nervous system

Brain and sacral spinal cord (craniosacral), long pre and short post ganglionic, ganglion located in visceral effector organs

Define sympathetic nervous system

Fight or flight - mobilises the body during activity and promotes adjustments during exercise or when threatened

Changes made by sympathetic nervous system

Skin vasconstricts, sweat glands secrete, pupils dilate, increases hr and contractility, dilated bronchioles, gut contracts sphincters, increase blood flow and force of contraction of muscles

Define parasympathetic nervous system

Rest and digest, promotes maintenance activities and conserves body energy

Changes made by parasympathetic nervous system

Skin is not innervation, sweat glands do not secrete, pupils construct, decreased heart rate, constricted bronchioles, relaxed sphincters, muscles probably not innervated

Cannot act on blood vessels

Define sympathetic tone

Keeps blood vessels in continual state of partial constriction

Receptors and neurotransmitters for sympathetic nervous system

Preganglionic neuron releases ACh, binds to nicotinic receptor on post ganglionic neuron, post ganglionic neuron releases noradrenaline, binds to adrenergic receptor (type of metabotropic receptor), releases g-protein

Types of adrenergic receptors

Alpha = 1 is excitatory and 2 is inhibitory (in sphincters and glands of gastrointestinal tract)

Beta = 1 is excitatory (cardiac muscle and liver) and 2 is inhibitory (bronchial smooth muscle and blood vessels)

Special cases for sympathetic nervous system

Innervation of adrenal gland - only one ganglion neuron (releases ACh, binds to nicotinic receptor on adrenal gland, secretes adrenaline/noradrenaline, acts on blood vessels)

Innervation of sweat glands - release of ACh acts on muscarinic receptors in sweat glands (releases ACh, binds to nicotinic receptors on post ganglionic, secretes ACh, beings to muscarinic receptor on sweat glands)

Receptors and neurotransmitters for parasympathetic system

Preganglionic neuron releases ACh, binds to nicotinic receptors on post ganglionic neuron, releases ACh, binds to muscarinic receptor (metabotropic - releases g-protein)