Lab 11 - Nervous system: Nervous Tissue and spinal cord Flashcards
what is the nervous system?
An intricate and complicated network of tissues that regulates all body processes
what is the function of the nervous system?
it receives sensory information, integrates that information, and initiates reactive measures. these functions revolve around the maintenance of homeostasis.
what is homeostasis?
the ability of the body to maintain a controlled and stable internal environment by responding to internal and external stimuli.
Structurally, what are the two major divisions of the human nervous system?
Central and Peripheral nervous system (CNS & PNS)
what makes up the CNS
the brain and spinal cord
what makes up the PNS
cranial and spinal nerves, ganglia and sensory receptors
how do the PNS and CNS work together?
the CNS processes the information received by the sensory receptors of the PNS, and the CNS controls the actions of all parts of the body and is also the site of thoughts, emotions, and memory
what are the two types of cells found in the nervous system?
neurons and neuroglia
what are neurons?
neurons, or nerve cells form the functional portion of the system. They are highly specialized of impulse conduction and are responsible for all the special attributes associated with the nervous system; thinking, controlling muscle activity and regulating glands
what are the three classes of neurons based on FUNCTION?
sensory (afferent), Interneuron (association neuron), and motor (efferent)
what are sensory (afferent) neurons?
conducts the impulse from the sensory receptor to the CNS
what are Interneurons (association neurons)?
integrates information from the sensory neurons and passes the stimulus to motor neurons
what are Motor (efferent) neurons?
conducts the impulse from the central nervous system to an effector, usually a muscle or gland
what are dendrites?
nerve fibers projecting from the cell body of a neuron that receive input from a neuron
what are cell bodies?
contains the nucleus surrounded by cytoplasm w/ cellular organelles including nissl bodies (free ribosomes & RER), lysosomes, mitochondria; they integrate information from dendrites and other synaptic inputs
what are the parts to an axon?
axon hillock, axon collateral, axon terminal, and synaptic end bulbs/varicosities
what is an axon hillock?
cone-shaped elevation that joins the axon to the body; info from dendrites & cell body are collected and conducted through axon hillock
what is an axon collateral?
side branches along the length of an axon; provide modulation & regulation of cell firing pattern & represent a feedback system for the neural activity
what is an axon terminal?
axons and collaterals divide into fine processes; sites where synapses with other neurons are found, and neurotransmitters are stored here to communicate with other neurons via synapses
what are synaptic end bulbs/varicosities?
tips of some axon terminals swell into bulb shaped structures (synaptic end bulbs) or string of swollen bumps (varicosities)
what are schwann cells?
type of neuroglia in the PNS that myelinates a single axon; participaes in axon regeneration
what is the myelin sheath?
multilayered lipid and protein covering surrounding axons; electrically insulates the axon of a neuron and increases speed of nerve impulse connection
what is neurolemma?
outer nucleated cytoplasmic layer that encloses that myelin sheath and ONLY FOUND IN AXONS IN THE PNS; forms regeneration tube that guides and stimulates the growth of an injured axons
what are myelin sheath gaps or nodes of ranvier?
specialized regions in between axons that are unmyelinated; facilitates rapid conduction of nerve impulses