Exam 3 Study Guide Anatomy and Physiology I The things highlighted in yellow were what his study guide said we needed to know Chapter 14 The Autonomic Nervous System ANS ANS is involuntary it is automatic This means it is independent of the brain Innervate nerve controls a cell controls smooth and cardiac muscle and glands Ex heart blood vessels bladder Viscera referring to internal organs abdomen and thoracic cavities Centers in the hypothalamus and brain stem do regulate ANS reflexes ANS autonomic differs from SMS somatic 1 Effectors tissue being stimulated in the ANS cardiac muscle smooth muscle and glands In SMS it is skeletal muscles 2 Efferent pathways axons of the ANS are a two neuron chain This means we need two neurons and synapses to connect to the organ First neuron Preganglionic lightly myelinated axon Second neuron Postganglionic extends to an effector organ The synapses occur in the ganglia ANS 1 synapse 2 neurons 1 ganglia 3 Target organ responses ANS divisions sympathetic and parasympathetic The divisions counterbalance each other Homeostasis Most organs have DUAL ANS innervation meaning they get impulses from both sympathetic and parasympathetic neurons Usually they do opposite things One division will stimulate The other division will decrease activity Sympathetic fibers increase heart and respiratory rates inhibit digestion and elimination Parasympathetic fibers decrease heart and respiratory rates allow for EXAMPLE they work in opposite of each other One acts like the accelerator digestion and discarding of wastes to a car the other acts as the brake ANS Anatomy Sympathetic Pathways Known as the thoracolumbar division From T1 to L1 Located in the lateral horns of gray matter in the 12 thoracic and first 2 lumbar segments of the spinal cord Only the adrenal gland is innervated here Parasympathetic division known as the craniosacral division Located in the brain stem nuclei and in the lateral gray matter in the second through fourth sacral segments of the spinal cord the purple shows the parasympathetic green pathway shows the sympathetic The parasympathetic nerve divisions are most important for internal organs The synapse is in ONE ganglia The sympathetic has two GANGLIAS One is near and parallel to the vertebral column and its called the sympathetic ganglia change ANS Neurotransmitters and Receptors Cholinergic neurons release the neurotransmitter Ach acetylcholine Adrenergic neurons release the neurotransmitter norepinephrine NE o Both are released by exocytosis Ach is released by ALL preganglionic axons in both sympathetic and parasympathetic and only PARASYMPATHETIC postganglionic axons Ach RECEPTORS On all effector cells stimulated by postganglionic cholinergic fibers The effect can either be inhibitory in the thoracic or excitatory in the abdomen NE of sympathetic stimulates thoracic cavity and inhibits abdominal cavity ACH of parasympathetic inhibits the thoracic and stimulates the abdominal cavity Neurotransmitters and receptors sympathetic Nervous System Adrenergic receptors bind norepinephrine and epinephrine Release norepinephrine o Alpha stimulate beta inhibit o Think of a machine that needs to be stimulated before inhibition alpha before beta Adrenergic fibers sympathetic postganglionic axons release NE Secretion of postganglionic 80 Nori 20 Epi Autonomic Nervous system Preganglionic fibers synapse in the chain ganglia They synapse with the collateral ganglia Postganglionic fibers innervate numerous organs of the body Most organs have dual innervations meaning they get effects from both sympathetic and parasympathetic Physiology of the ANS Sympathetic Division ROLE fight or flight system All the E s exercise excitement emergency embarrassment Regulates many functions Adrenal medulla sweat glands kidneys blood vessels Vasoconstriction increased sympathetic activity Vasodilatation decreased sympathetic activity Metabolic effects Blood glucose levels Mobilize fat as energy Parasympathetic Division ROLE all the D activities digestion defecation diuresis Relaxing after a meal Blood pressure heart rate respiratory rates are low GI tract is high When we are at rest the parasympathetic division is high It stimulates the Skin is warm pupils are constricted digestive system Responses o Salvation o Urination o Digestion o Defecation The ANS is regulated by feedback loops between spinal cord and brainstem Oversight by the hypothalamus Acetylcholine and Catecholamine s Ach and catecholamine s epi and nori Ach inhibits the heart catecholamine s aka NE and EPI stimulate the heart Parasympathetic inhibits the heart and stimulates abdomen Sympathetic stimulates the heart and inhibits the abdomen Endocrine System Hormones chemical substances secreted by cells into the blood Regulate the metabolic function of other cells Endocrine is secreted into the blood stream Chemistry of hormones 1 Amino acid based hormones a Amines thyroxin peptides proteins b One amino acid will produce a hormone 2 Steroids a Synthesized by cholesterol b Gonadal and adrenocortical c Testosterone and the related hormones d Estrogen and progesterone for females Mechanisms of Hormones hormone 1 Water soluble hormones all amino acid based hormones except thyroid a Receptor is in the plasma membrane 2 Lipid soluble hormones steroid and thyroid hormones a They have it in the cytoplasm or INSIDE the cell The steroid hormone has to bind to two receptors One is in the nucleus receptor hormone complex and then it has to bind to DNA Hormones circulate to all tissues but only activate target cells They have specific receptors which the hormone binds to it In the test it is usually easy ACTH adrenal cortex trophy hormone would bind to the ADRENAL CORTEX It usually has it in the name Interaction of Hormones at Target Cells There are two types of hormone interactions Synergism more than one hormone produces the same effects on a target cell o Both epinephrine and glucagon INCREASE blood glucose Antagonism Two hormones that have OPPOSITE effects o Insulin decrease blood glucose o Glucagon increase blood glucose Blood levels of hormones are controlled by negative feedback systems Always working to return to homeostasis Control of Hormone Release 1 Humoral Stimuli changing blood levels of IONS Ca2 Na K and NUTRIENTS glucose or insulin directly stimulates secretion of hormones 2 Neural stimuli neurotransmitter stimulate the gland to secrete its hormone sympathetic nervous system fibers stimulate the adrenal
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