Autonomic Nervous system: - Consists of Motor Neurons that: o Innervate (supply of nerves) smooth and cardiac muscle and glandso Make adjustments to ensure optimal support for bodyo Subconscious controlo Have viscera as most of their effectors- Different than SNS becauseo Has effectors (away from brain) For SNS- skeletal muscles For ANS- cardiac muscle (Heart), smooth muscle, and glandso Efferent pathways2 Neuron Motor Chain- so needs 2 neurons to connect to the organ1. Preganglionic neuron has a lightly myleniated axon 2. (Post)Ganglionic- neuron extends to an effector organ witha soma for the responseo Target organ responseso ANS 1 snyapse = 2 Neurons & 1 Ganglia- Sympathetic and Parasympathetic DIVISIONSo These 2 divisions counterbalance each othero Most of the body organs have dual ANS intervention, which is receiving impulses from both division’s neurons (usually one stimulates and the other decreases activity)- Interactionso Both divisions’ fibers innervate most visceral organs o This results in Dynamic antagonisms that precisely control visceral activityo Sympathetic fibers INCREASE heart rate and respiratory rates, and inhibit digestion and eliminationo Parasympathetic DECREASE heart rate and respiratory rates, allowing digestion and elimination- ANS Neurotransmitter and Receptoro ACh and NE are the 2 major neurotransmitters of the ANSo ACh is released by all preganglionic axons and all parasympathetic postganglionic axonso Cholinergic fibers- ACh releasing fibers!!- ACh Receptorso All ACh receptors on ALL ORGAN (EFFECTOR) cells are stimulated by postganglionic cholinergic fiberso ACh binding depends on the receptor type of the target organ and can either be inhibitory or excitatory Thoracic- Inhibits Abdomen- Exciteso In Parasympathetic~ CRANIOSACRAL Vague Nerve (aka “X”) its soma extends from medulla oblongata (most pre-ganglionic parasympathetic neurons extend from here and the rest extend from sacral part of craniosacral divisiono Sympathetic- T1-L2 (THORALUMBAR) The adrenal gland (part of kidneys) is ONLY innervated bysympathetic; no post-ganglionic neuron “collateral” ganglia- (farther away from vertebrae) sympathetic ganglia that is unpaired and located between the chain and the organ; sympathetic “chain” ganglia- paired, parallel to one another (these pairs can be seen on the below diagram from T1 to L2) T5-L2 splanchnic nerves synapse with/collateral ganglia- SNS Neurotransmitters and Receptorso Adrenergic fibers- sympathetic postganglionic axons that release NE The receptors are of two types (alpha or beta) Alpha- NE binds to stimulatory, 2 subclasses (blood vessels) Beta- NE binds to inhibitory, 3 subclasses (GI tract, pancreas, adipose tissue)o Neutransmitters can be excitatory or inhibitory depending uponthe receptor type- Sympathetic outflowo From spinal cord (T1-L2)o Preganglionic fibers synapse in the chain (paravertebral) gangliao Fibers from T5-L2 form splanchnic nerves (abdomen) and synapse with collateral gangliao Postganglionic fibers innervate the numerous organs of the body o The paravertebral ganglia form part of the sympathetic trunk or chaino About 23 ganglia- 3 cervical, 11 thoracic, 4 lumbar, 4 sacral, and 1coccygeal- Adrenal Medullao Fibers of thoracic splanchnic nerve pass directly to the adrenal medullao A “misplaced” sympathetic gangliono Part of the ANS and ENS (Endocrine)o Upon stimulation, medullary cells secrete Catecholamines (NE and EPI) into the blood and can only be secreted by Postganglionic SympatheticNE= NorpinephrineEPI- Epinephrine- Sympathetic Division’s Roles and Unique Roleso Fight or flighto Involves E activities- exercise, excitement, and embarrassment.. STRESSo Regulates many functions not subject to parasympathetic influence Examples; adrenal medulla, sweat glands, kidneys, and most blood vessels- Metabolic effects of SNSo Promotes metabolic effects that are NOT REVERSED by the parasympathetic division Increase metabolic rate of body cells Raise blood glucose levels Mobilize Fat as an energy source- PNS Roleso D activities- digestion, defection, and diureses (relaxing after a meal)o Lowers blood pressure, heart rate, and respiratory rateo GI tract activity is higho Warm skin, pupils contstricy (NAP TIME)- ANS Physiology- PNS ResponsesSUDD- (Salivation, Urination, Digestion, Defecation) all INCREASEDThe balance of the ANS sympathetic and Parasympathetic tone is regulated by feedback loops between the spinal and the brainstem, with input from the limbic system and oversight by hypothalamus.An important thing to remember about Parasympathetic neurons is that the Vagus nerve innervates the atrium of the heart and the gastrointestinal systemEndocrine System- response occur slowly but last longer than those of the nervous system (works with the nervous system to regulate body activity)- Hypothalamus Role- belongs to the nervous system but secrets hormones that control the endocrine system. - Adrena Medulla- Part of the nervous and the endocrine system that is housed by the adrenal cortex which secretes many types of hormones- Pancreas has endocrine and exocrine cells, endocrine cells secrete glucagon and insulin (talked more about later).- Hormones- chemical substances secreted by cells into the bloodo Regulate the metabolic function of other cells- 2 main classes1. Amino acid-based hormonesCatecholamines, amines, thyroxine, peptides, insulin, and proteinsReceptors OUTSIDE the cell2. Steroids- synthesized from cholesterolProuduced in Gondal and adrenocortical (adrenal cortex)Receptors inside the cell (1st nucleus and 2nd DNA) - Mechanism of Hormones Actiono Hormone action on target cells1. After membrane permeability of membrane potential by opening or closing ion channels2. Stimulate synthesis of proteins3. Activate/deactivate enzyme systems4. Induce secretary activity5. Stimulate mitosis- 2 mechanisms depending on their chemical nature1. Water Soluble (all amino acid-based hormones except thyroid hormone) Cannot enter target cells Act on plasma membrane Couple by G Proteins to intracellular second messangers2. Lipid Soluble- (Steroid and thyroid hormones) Acts on intracellular receptor that directly activate gene activity and mRNA sends out a message to produce protein, to tell muscle to get bigger- Hormone Receptoro Is a protein molecule to which a particular molecule binds stronglyand responds to several different hormoneso So, a hormone
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