Chapter 13 - Neural Tissue Flashcards
What is the transmission of signals in the nervous system?
- Body parts to the central nervous system
- Central nervous system to the body parts
- Coordinate all body systems
- Accomplished by the transmission of signals
Nervous system
What kind of signaling does the nervous system do?
Electrochemical signaling
- Slower scale
- Uses chemicals in the blood stream called hormones
Endocrine system
Nervous system is made up of many organs, each composed of several tissues
- Connective tissues
- Blood vessels
- Neurons
- Neuroglia
Two groups and divisions of the nervous system
- Central NS
2. Peripheral NS
Brain and spinal cord
CNS
Cranial and spinal nerves and ganglia
PNS
Five characteristics of the CNS
- Brain and spinal cord
- Covered by meninges
- Starts as a hollow tube
- Bathed in cerebrospinal fluid
- Integration center
Three components to the PNS
- Consists of CRANIAL and SPINAL NERVES and GANGLIA that contain both SENSORY and MOTOR FIBERS
- Connects CNS to muscles, glands and all sensory receptors
- Brings info to and from the CNS
Two divisions of the PNS
Afferent division = sensory
Efferent division = motor
Two divisions of the efferent division
Somatic division = conscious
Autonomic division = unconscious
General functions and processes of the CNS and PNS
- Receptors = direct stimuli
- Sensory = afferent PNS
- Integrative = CNS
- Motor = efferent PNS
- Effector = muscle/gland
- Structural and functional units
- Excitable
- Amitotic
Neurons
- Accessory cells
- Act like connective tissue
Neuroglial cells
Three major structures of neurons
- Soma
- Dendrites
- Axon
Cell body is mononucleate
Soma
The parts of the Soma
Nissl bodies = ribosomes clusters; give gray color
Axon hillock = connects soma to axon
Perikaryon = region around the nucleus
Neurofibrils = cytoskeleton that extend into dendrites/axons; gives shape
Four characteristics of dendrites
- Respond to neurotransmitters
- Short, branched, UNMYELINATED
- Specialized for contact with other nuerons
- Conducts impulses towards the cell body
Four characteristics of axons
- Only one cell
- Conducts nerve impulses away from soma
- Can give off collaterals
- Many wrapped in myelin sheath; glial cells wrapped around the axon
Where does the axon end?
Synaptic terminal
What does the axon produce?
Neurotransmitters
The axons may contact what three things?
- Another neuron
- Muscle fibers
- Glands
- also known as axoplasmic flow
- movement of cellular materials (not signals) through the axon
Axonal transport
- Away from soma; neurotransmitters, organelles, nutrients
Anterograde
Toward soma; degraded materials to be recycled and extracellular substances
Retrograde
The cytoplasm of an axon
Axoplasma
What does the axoplasma consist of?
- Few Organelles
- Cytoskeletal proteins
What do cytoskeletal proteins do?
- Form cytoskeleton
- Maintain shape
- Generate axonal transport
Plasma membrane of axons
Axolemma
What does the axolemma consist of?
Collaterals: side branches
Telodendria: terminal extensions
Synaptic terminal: contains synaptic vesicles; where neruon contacts postsynaptic cell
Sructural classification of neurons is based on what?
The number and morphology of dendrites
The structural classification of neurons
- Anaxonic
- Bipolar
- Unipolar
- Multipolar
- Small neurons
- Axons can not be distinguished from dendrites
Anaxonic
Where are anaxonic structures of neurons
CNS, especially interneurons that coordinate special senses
Three characteristics of bipolar structures of neurons
- Several small dendrites converge into one
- Dendrite and axon separated by soma
- Unmyelinated
Where is the bipolar structure of a neuron?
Sensory neurons of special sensory organs
Another name for unipolar structures of neurons
Pseudo-unipolar
- Several small dendrites converge onto one large one
- Dendrite and axon continuous
- Usually myelinated
Unipolar