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Handout5TA - Autonomic System o o Maintains homeostasis 2...

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Autonomic System: o Maintains homeostasis o 2 branches: Parasympathetic: rest and digest Sympathetic: fight, flight, fright, f*** (sex). o During sexual responses, both the parasympathetic and sympathetic nervous system are activated together. The parasympathetic system initiates it and the sympathetic system is responsible for the orgasm o The main centers for the autonomic system are the brain and spinal chord o Sensory inputs generate outputs from the medulla, mid brain, hypothalamus, and pons. Information is also received from the limbic system which is responsible for emotions o 2 neurons are always in autonomic pathways Efferent portion: one synapse in the peripheral nervous system. These are autonomic neurons which synapse with target tissues NT released Post ganglionic neurons: synapse with target tissues Pre ganglionic neurons: cell bodies are in the CNS Pre – ganglionic transmitter Post – ganglionic receptor Post – ganglionic transmitter Receptors on target organs Sympathetic Acetylcholine Nicotinic cholinergic Nor-epinephrine Adrenergic ( can be either or α β Parasympathe tic Acetylcholine Nicotinic cholinergic Acetylcholine Muscarinic cholinergic
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o Sympathetic location: preganglionic neurons in the thoracic and lumbar regions of the spinal cord and the brain o Parasympathetic location: brain and the sacral region of the spinal cord. Preganglionic fibers originate out of cranial nerves and innervate the face, neck, thorax, and abdomen (liver, stomach, spleen, liver, and intestine, and colon). The sacral region innervates the pelvic organs One of the main parasympathetic nerves is the cranial nerve #10: The vagus nerve (a post ganglionic fiber). Its pre ganglionic fibers are in the medulla. o Parasympathetic effects: (Study figure 11-5 It will probably be on the midterm… if you want to do well, you will study it!) Vagus nerve effects: Lungs: bronchial constriction and an increase in secretion of mucus (in order to expel irritants) stimulates ventilation. Heart: pacemaker cells to decrease the heart rate by opening K channels. GI tract: increase motility and secretion. Pancreas: increase insulin secretion. Non vagus nerve but post – ganglionic nerve effects: Eyes: pupil constriction. Salivary glands: increased saliva. Pelvic organs : contraction of urinary bladder, uterus, and rectum. Genitalia: erection in males, and lubrication and erection in females. o Sympathetic effects Pupil: Dilation Salivary glands: inhibits salivation, increased mucus secretion
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Heart: increases the heart rate and force of contraction Lungs: mainly epinephrine secreted from the adrenal medulla to dilate bronchioles. (Think inhalers for people with asthma or Epi Pens!) GI tract: inhibits motility and secretion Kidneys: increases filtration Pelvic organs: relaxes sphincters to inhibit contractions and in sex organs, acts as an inhibitor during arousal
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Handout5TA - Autonomic System o o Maintains homeostasis 2...

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