CHAPTER 12 Flashcards
(43 cards)
Endocrine System
chemical messengers secreted into to the blood
Nervous System
electrical and chemical means to send messages from cell to cell
Nervous system three basic steps
-Sense organs receive body info and transmit message to the CNS
-CNS processes this info and determines response
-CNS issues commands to muscles and gland cells to carry out response
Two subdivisions in nervous system
CNS- brain and spinal cord
PNS- everything else (nerve axons and ganglion)
ganglion
knot like swelling in nerve right off CNS Spinal cord
PNS contains what divisons
afferent- sensory output (carries receptors to CNS)
efferent- sensory
Efferent- motor output (CNS to effectors)
Afferent Sensory motor divisions
Somatic- carriers signals from receptors in skin, muscles bones, joints
Visceral- carries receptions from heart, lungs, stomach, bladder
Efferent motor divisions
Somatic- carries signals to skeletal muscle
visceral- Autonomic (sympathetic(f/f) and parasympathetic (r/d))
Universal Properties of Neurons
Excitability
* Respond to stimuli
Conductivity
* Produce electrical signals that travel along nerve fibers to reach other cells
Secretion
* Nerve fiber endings (axon terminals) release chemical
neurotransmitters that influence other cells
Interneurons
In CNS
connects motor and sensory
receive signals
Structure of a Neuron
Soma- neuron soma cell body
-dendrites
-axon (nerve fiber)
Structural Classification of Neurons
multipolar- one axon, multiple dendrites (most neurons in CNS)
bipolar- one axon and one dendrite (olfactory, retina, inner ear)
unipolar (single) and anaxonic (no axon)
Axonal transport
proteins and peptides made in the soma are transported by:
* Anterograde transport—down the axon away from soma
* Retrograde transport—up the axon toward the soma
Four types of glia occur in the CNS
Oligodendrocytes- Form myelin sheaths
ependymal cells- secrete CSF, line ventricles
microglia- immune system, CNS macrophages (“eat”)
astrocytes- most abundant, BBB, regulate environment
myloin will have what reaction
fast reaction
Two types of glia occur in the PNS
-schwann cells- Form myelin sheaths, nerve regeneration/repair
-Satellite cells- regulate environment
Myelination
-begin at week 14 of fetal development
-the process by which axons are covered by myelin sheaths
-During myelination, Oli nucleus cannot migrate around the
axon like Schwann cells
Myelin Sheaths are formed by
-Oligodendrocytes in CNS
* Schwann cells in PNS
Nerve regeneration
-axon by injury degenerates
-neurosoma swells and moves nucleus off center
-axon stump sprouts
-schwann cells, basal lamina form regeneration tube (can take up to two years)
Nerve signal travels down an axon depends
on two factors
-diameter- more SA will be faster
-myelin
conduction speed
how fast electrical signals move through a nerve
Nerve growth factor
protein secreted by gland etc and picked up by axon terminals, enables growing
Electrical Potentials
-Electrical potential-Difference in electrical charge between one point and another causing flow between
-Membrane potential-Caused by separation of ions across the cell membrane, inside negative
Electrical Currents
-Electrical current- flow of charged particles
-Bioelectricity and current flow- ions are charge carriers , Gated channels can open and close to control ionic current