Chapter 12: Nervous Tissue Flashcards
Central Nervous system consists of
the brain and spinal cord
Peripheral nervous system consists of
- cranial nerves
- spinal nerves
- enteric plexus in small intestine
- sensory receptors in the skin
What are somatic senses
receptors for pain, itch, vibration, pressure (distributed throughout the body)
What are special senses
only in specific areas such as eyes (seeing), ears (hearing), tongue (taste)
Somatic nervous system (CNS)
skeletal muscle ( able to control)
Autonomic nervous system (CNS)
- sympathetic division (fight or flight)
- parasympathetic division (rest and digest)
^ smooth muscle, cardiac muscle, and glands - enteric plexus: smooth muscle and glands of digestive canal
Functions of the nervous system
- Sensory: detect changes through sensory receptors
- Integrative: analyze incoming sensory information, store some aspects, and make decisions regarding appropriate behaviours
- Motor: respond to stimuli via effectors
Characteristics of neurons
- electrically excitable (like muscle cells)
- do not divide and multiply
- cell body has normal cellular structures
Nerve impulse is called an
action potential
Parts of a neuron
Dendrites: listen to the gossip
Cell body: has nucleus, mitochondria etc
Axon: can be long or short, Transmit electrical impulses away from the cell body to other cells
3 Different structural classifications of neurons (classified based on number of processes extending from cell body)
- Multipolar neuron
- Bipolar neuron
- Pseudounipolar neuron
Functional classification of neurons (classified based on direction of nerve impulse propagation)
- Sensory/Afferent neurons: conveys information to CNS
- Motor/Efferent neurons: conveys action potential from the CNS
- Interneurons/Association neurons: process sensory information and elicit motor response
Most sensory neurons are…
unipolar
Most motor neurons are…
multipolar
Most interneurons are …
multipolar
Interneurons are responsible for
transmitting impulses between sensory and motor neurons. Most abundant
Neuroglia characteristics
- not electrically excitable
- make up about half of the volume of the nervous system
- can multiply and divide
- 6 types
What are the 4 types of neuroglia in the CNS
- astrocytes
- oligodendrocytes
- microglia
- ependymalF
Function of astrocytes
- support neurons in the CNS
- maintain the chemical environment (Ca2+ and K+)
Function of oligodendrocytes
produce myelin in the CNS
Function of microglia
participate in phagocytosis
Function of ependymal cells
form and circulate CSF
What are the 2 types of neuroglia in the PNS
- Satellite cells
- Scwann cells
Function of Satellite cells
- provide structural support
- regulate the exchanges of materials between neuronal cell bodies and interstitial fluid
Function of Schwann cells
they form the myelin sheath around axons in the PNS just like oligodendrocytes in the CNS
Function of myelin sheath
- insulates and protects electrical signals
- fat ( causes the plasma membrane to look thicker on slides) - plasma; lipid bilayer
Gray matter vs white matter
- White matter: composed of primarily myelinated axons
- Gray matter consists of unmyelinated axons
Membrane potential
the difference in charges between the inside and the outside of the cell
How to neurons (excitable cells) communicatte with one another
via action potentials or graded potentials
Action potentials Vs Graded potentials
allow communication over short and long distances whereas graded potentials allow communication over short distances only
What determines production of AP or GP
depends on the existence of a resting membrane potential and the existence of certain ion channels
Ion Channels; Leak channels (description + location)
- gated channels that randomly open and close
- found in nearly all cels, and dendrites, cell bodies, and axons of all types of neurons
Ion Channels; Ligand -gated channels (description + location)
- gated channels that open in response to binding of ligand (chemical) stimulus
Ion Channels; Mechanically-gated channels (description + location)
- gated channels that open in response to mechanical stimulus (such as touch, pressure, vibration, or tissue stretching)
Ion Channels; Voltage-gated channels (description + location)
- gated channels that open in response to voltage stimulus (change in membrane potential)
Resting membrane potential
- the membrane of a non-conducting neuron is positive outside and negative inside.
What is resting membrane potential (negative inside and positive outside) determined by:
- unequal distribution of ions across the plasma membrane and selectively permeability of the neuron’s membrane to Na+ and K+
- most anions cannot leave the cell (negatively charged have to go through membrane proteins)
- Na+/K+ pumps
Graded potentials
- small deviations in resting membrane potential
A graded potential occurs in response to the opening of a …
mechanically-gated or ligand-gated ion channels
