Chapter 6 Section D: Anatomy 7 October 2011 Chapter 6 Section D: Anatomy

1QQ # 13 for 8:30 class Which will activate muscarinic acetylcholine receptors? acetylcholine nicotine muscarine curare atropine. Nicotinic acetylcholine receptors Are metabotropic receptors. Can be activated with nicotine. Can be activated with acetylcholine. Can be blocked with muscarine. Can be activated with atropine.

1QQ # 14 for 8:30 class Pain and temperature information Is carried in the spinothalamic tract Is carried in the dorsal column/medial lemniscal tract Crosses (decussates) in the spinal cord Is relayed to the somatosensory cortex via 3rd order neurons in the thalamus Is carried in the anterolateral tract. Which are true of touch and proprioception pathways? Second order neurons are located in the dorsal column nuclei Axons of first order neurons travel in the spinothalamic tract Axons of first order neurons decussate (cross the midline) in the spinal cord Axons of second order neurons travel in the medial lemniscus. Axons of first order neurons ascend in the dorsal columns and synapse onto second order neurons in the dorsal column nuclei.

1QQ # 13 for 9:30 class Which will block muscarinic acetylcholine receptors? acetylcholine nicotine muscarine curare atropine. Muscarinic acetylcholine receptors Are metabotropic receptors Can be activated with nicotine Can be activated with acetylcholine Can be blocked with muscarine Can be activated with atropine.

1QQ # 14 for 9:30 class Pain and temperature information Is carried in the anterolateral tract Is carried in the dorsal column/medial lemniscal tract Crosses (decussates) in the medulla Is relayed to the somatosensory cortex via 3rd order neurons in the thalamus Is carried in the spinothalamic tract. Which are true of touch and proprioception pathways? First order neurons are located in the dorsal column nuclei Axons of first order neurons travel in the spinothalamic tract Axons of first order neurons decussate (cross the midline) in the spinal cord Axons of second order neurons travel in the medial lemniscus. Axons of first order neurons ascend in the dorsal columns and synapse onto second order neurons in the dorsal column nuclei.

Types of Ligand-Gated Receptors = ACH = Acetylcholine Inotropic receptor Metabotropic receptor Agonist = Nicotine Agonist = Muscarine Antagonist = Curare Antagonist = Atropine Types of Acetylcholine Receptors so named for agonist: Nicotinic AChR and Muscarinic AChR

S 2 Pharmacological agents intended to act in brain must be able to cross blood-brain barrier. Treatments for Parkinsonism: a) tablets of L-Dopa (which crosses the BBB) unlike Dopamine (which would have widespread effects) b) electrical stimulation c) neuronal transplants (self, fetal, stem cell, pig) NIH Stem Cell Information Who Cares? Parkinsons Disease

12 pairs of cranial nerves 31 pairs of spinal nerves Touch, pain, temperature, proprioception Vessel stretch, O2, CO2, etc. Vision, taste, smell, hearing, equilibrium 12 pairs of cranial nerves 31 pairs of spinal nerves Skeletal Muscle Smooth muscle Cardiac muscle Glands Tracts, pathways, commissures Nuclei Control of digestive functions in quadraplegics via enteric nervous system. Nerves & Ganglia

S 4 Figure 6.38

S 5 Figure 6.39 Components of gray matter Amygdala & Hippocampus

S 6 How do we know the functions of various brain regions? Analogy: experiments to discover the function of a battery in a car. a) Correlations of deficits of stroke victims with brain regions affected. b) Selective ablations. c) Selective electrical and chemical microstimulation i) Dr. Hettes’s experiments on rats ii) Neurologist Wilder Penfield & Epilepsy

S 7

S 8 Homunculus = representation of body parts

S 9 Dorsal roots = sensory (afferent) Ventral roots = motor (efferent, both somatic and autonomic) Gray matter regions of brain and spinal cord “Pinched nerves” and bulging discs Ascending and descending axonal tracts in white matter not anatomically delineated. Atlanta-Boston flight Origin-Destination Naming of white matter tracts…..

S 10 Explanation for Cervical and lumbar enlargements of spinal cord. Spinal nerves named for vertebral level. Using patient’s localization of symptoms with knowledge of dermatomes to determine which spinal nerve is affected by damage. Epidural injections into region of cauda equina of Lidocaine-like agents to block action potentials in sensory and motor axons without risk of damage to spinal cord. 8 12 5 5 1