BIO 240 1st Edition Lecture 29 Outline of Last Lecture I Anatomy of Spinal Cord i Tracts White matter ii Gray Matter iii Roots Outline of Current Lecture I Peripheral Nervous System A Synapses B Receptors Current Lecture I Peripheral Nervous System A Synapses Where two or more neurons meets 1 Polysynaptic Pathways 99 9 of the pathways in our body Have 3 or more neurons synapsing 2 Monosynaptic Pathways Where 2 neurons synapse only one sensory neuron and one motor neuron Only make up 0 1 of our body s pathways Also known as reflexes For example Achilles tendon patellar tendon gag reflex and blinking Much faster because it bypasses the brain by skipping ascending tracts and descending tracts B Receptors of the Nervous System Occur in the brain too chemoreceptors 1 Specialized cells or tissues that respond to internal or external stimuli The translators or communicators for the nervous system 2 Categories by stimuli a Mechanoreceptors Activated by a physical force b Chemoreceptors Activated by chemicals for example neurotransmitters c Photoreceptors Activated by light Detect light and are only found in the retina of the eye There are two types of photoreceptors rods and cones d Baroreceptors Activated by pressure Stimulated by pressure and pressure changes Monitor blood pressure Occur in carotids and aorta e Thermorecpetors Activate by temperature Monitor temperature These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Nociceptors Activated by pain Specific receptor for all types of pain There are none in the brain This is why you don t feel a tumor in the brain until it grows and impedes functions or grows to tissue outside of brain 3 Mechanoreceptors a Meissner s Tactile Corpuscles Occur in the papillary dermis Detect fine touch b Pacinian Corpuscles Occur in the deep dermis and the hypodermis Are for deep pressure sensations but only for about 3 seconds c Ruffini Endings Occur in the deep dermis and hypodermis and joints Are for deep continuous pressure 4 Chemoreceptors Are located in the CNS and PNS Helps control the ANS using neuro transmitters a Cholinergic receptors Stimulated by AcH or mimics of AcH i Nicotinic Nicotine mimics AcH Found in the adrenal glands ii Muscarinic The mushroom poison muscarine activates these receptors Found on parasympathetic fibers and sweat glands which are on sympathetic fibers b Adrenergic receptors Stimulated by epinephrine and Norepinephrine i Alpha 1 and 2 Found on blood vessels and constrict blood vessels when activated ii Beta 1 and 2 Found on heart and bronchioles 1 Clinical application Developing drugs that can bind with the receptors Beta blockers block the beta 1 receptors on the heart Blocks the attachment of adrenaline to the heart to keep its rhythm more consistent f
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