PhysiologyPhysiology

Carla Thompson

Talmage Harrold

Lydia McDore

•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

Introduction to Physiology

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

Left

Hemisphere

Controls the right side of the body.

Bilateral symmetry

Right

Hemisphere

Controls the left side of the body.

Lobes of the Brain

Brain OrganizationBrain Organization Medulla oblongata- breathing and heart rateMedulla oblongata- breathing and heart rate Pons- Sleep and arousalPons- Sleep and arousal Cerebellum- voluntary muscle control and motor Cerebellum- voluntary muscle control and motor

coordination coordination Hypothalamus- links autonomic nervous system to Hypothalamus- links autonomic nervous system to

endocrine system, growth, living, and emotions.endocrine system, growth, living, and emotions. Thalamus- relays input from senses to higher Thalamus- relays input from senses to higher

structuresstructures Hippocampus- processes memoriesHippocampus- processes memories Cerebral cortex (Neocortex)- organizes Cerebral cortex (Neocortex)- organizes

information and initiates responses. information and initiates responses.

Colliculi

Superior colliculus- hand-eye coordination

rapid eye movementInferior colliculus- receives

input from auditory stimulus, controls your response to loud noises

http://en.wikipedia.org/wiki/SuperiorColliculi

Endocrine SystemEndocrine System

Secretes hormonesSecretes hormones

Hormones are chemicals secreted by Hormones are chemicals secreted by endocrine glands that are carried through endocrine glands that are carried through the bloodstream to affect various body the bloodstream to affect various body parts.parts.

Endocrine System Con’tEndocrine System Con’t Pituitary gland- master gland, in brain, which secretes Pituitary gland- master gland, in brain, which secretes

releasing hormones that “turn on” other endocrine releasing hormones that “turn on” other endocrine glands.glands.

Thyroids- in neck, produce thyroxin which regulates Thyroids- in neck, produce thyroxin which regulates

growth, activity levels and metabolismgrowth, activity levels and metabolism. . Adrenals- near kidney, produce ACTH outside the gland, Adrenals- near kidney, produce ACTH outside the gland,

produce adrenaline/ noradrenalin inside the gland.produce adrenaline/ noradrenalin inside the gland. Pancreas- near stomach, produces insulin and glucogen.Pancreas- near stomach, produces insulin and glucogen.

IInsulin- glucose absorbtion mechanismnsulin- glucose absorbtion mechanism

Glucogen- hypoglycemiaGlucogen- hypoglycemia

Sex glands- ovaries and testesSex glands- ovaries and testes Ovaries-produce estrogen and progesteroneOvaries-produce estrogen and progesterone Testes- produce testeroneTestes- produce testerone

Natural SelectionNatural Selection

• Nature selects the best Nature selects the best adapted varieties to adapted varieties to survive and to survive and to reproduce. Darwin reproduce. Darwin called this “survival of called this “survival of the fittest.”the fittest.”

http://anthro.palomar.edu/evolve/evolve_2.htmhttp://anthro.palomar.edu/evolve/evolve_2.htm