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Physiology Carla Thompson Talmage Harrold Lydia McDore Introduction to Physiology •The study of processes and functions, incidental to, and characteristic of, life. •Physiology is an integrative science; examining body operation at all levels of organization, from cells to organs. •Homeostasis, flexibility, cell-to-cell communication, information transfer across cell membranes, energy flow in biological systems, and mass balance are six major themes in physiology. http://cwx.prenhall.com/bookbind/pubbooks/silverthorn2/ www.brainydictionary.com The Nervous System • Central Nervous System consists of the brain and spinal cord. • Peripheral nervous system consist of the cranial nerves, the spinal nerves, and visceral nervous system. • The Neuron is an individual nerve cell. http://cas-cousres.buffalo.edu/classes/phy/segal/2472000/247neuro.htm The Neuron •Types of Neurons •Afferent Neurons (sensory) transmit information from tissues and organs into the central nervous system. •Efferent neurons (Motor) convey signals from the central nervous system to the effector cells. •Interneuron connect neurons within specific regions of the central nervous system. •Parts of the Neuron •Axon carries synapse away from the cell body. •Dendrite receive synaptic information and it travels toward the cell body. •Cell Body (Soma) where information is integrated into the neuron. http://en.wikipedia.org/wiki/Neuron http://distance.stcc.edu/aandp/AP/AP1pages/nervssys/unit10/neurons.htm Nerve Conduction • Neurons are specifically designed to transmit information. • Presynaptic neurons send the neuron. • Postsynaptic neurons receive the neuron. • Active neurons (excitatory) produce an action potential which travels down the neuron. • A synapse releases neurotransmitters that change the electrical potential of the next neuron. • Inactive neurons (inhibitory) simply do not react. http://cas-cousres.buffalo.edu/classes/phy/segal/2472000/247neuro.htm Curare • Comes from two South American plants Strychnos taxifera and Chondrodendron tomentosum. • A muscle relaxer used in anesthesia. • Blocks acetycholine (ACh) receptors on the postsynaptic membrane of the neuromuscular junction. http://en.wikipedia.org/wiki/Curare Myelination • The process in which reserve cells are covered by and insulated with a layer of fat cells. • Increases the speed of information which travels through the peripheral nervous system. www.mc.maricopa.edu/dept/d46/psy/dev/fall99/prenatal/brain.html All-or-None Principle • Action potentials are approximately equal in size and shape (amplitude) under normal circumstances. • The size and shape of the action potential are independent of the intensity of the stimulus that initiated it. • Temporal summation is the process whereby a stimulus that is below threshold will elicit a reflex if the stimulus occurs repeatedly. • Spatial summation is the process whereby two or more stimuli that are individually below threshold will elicit a reflex if they occur simultaneously at different points on the body. http://www.miracosta.cc.ca.us/home/sfoster/neurons/glossary.htm http://www.wwnorton.com/college/pysh/gman5/glossary/T.htm Brains and Evolution • Physical factors and time are constraints against evolutionary changes for the brain. • The nearer to the front of the brain we go, the ‘newer’ it is. • The hindbrain controls more primitive functions- - heart rate and breathing- - where as the forebrain controls more thought and logical patterns – - -planning and behavior. The Brain Bilateral symmetry Left Right Hemisphere Hemisphere Controls the right side of the body. Controls the left side of the body. Lobes of the Brain Brain Organization Medulla oblongata- breathing and heart rate Pons- Sleep and arousal Cerebellum- voluntary muscle control and motor coordination Hypothalamus- links autonomic nervous system to endocrine system, growth, living, and emotions. Thalamus- relays input from senses to higher structures Hippocampus- processes memories Cerebral cortex (Neocortex)- organizes information and initiates responses. Colliculi Superior colliculus- handeye coordination rapid eye movement Inferior colliculusreceives input from auditory stimulus, controls your response to loud noises http://en.wikipedia.org/wiki/Supe riorColliculi Endocrine System Secretes hormones Hormones are chemicals secreted by endocrine glands that are carried through the bloodstream to affect various body parts. Endocrine System Con’t Pituitary gland- master gland, in brain, which secretes releasing hormones that “turn on” other endocrine glands. Thyroids- in neck, produce thyroxin which regulates growth, activity levels and metabolism. Adrenals- near kidney, produce ACTH outside the gland, produce adrenaline/ noradrenalin inside the gland. Pancreas- near stomach, produces insulin and glucogen. Insulin- glucose absorbtion mechanism Glucogen- hypoglycemia Sex glands- ovaries and testes Ovaries-produce estrogen and progesterone Testes- produce testerone Natural Selection • Nature selects the best adapted varieties to survive and to reproduce. Darwin called this “survival of the fittest.” http://anthro.palomar.edu/evolve/evolve_2.htm