Module 2 - Muscle and Nervous Tissues Flashcards
What type of muscle has: very long muscle fibers, under voluntary control, striated, located in the muscles that move our arms, legs, head, neck, and trunk, cannot divide but has other cells that can regenerate new cells of its kind
Skeletal Muscle
What type of muscle has: striated, under involuntary control, located in the heart, contains intercalated discs and gap junctions, muscle cells branch, CANNOT divide or generate new cells
Cardiac Muscle
What type of muscle has: small cells with tapering ends, under involuntary control, located in the walls of blood vessels and hollow organs, capable of dividing and generating new cells
Smooth Muscle
Contractility
Ability to exert tension by actively shortening
Elasticity
Muscles ability to return to its original length after contraction
Excitability
Ability to respond to stimulation
Extensibility
Ability to stretch over a range of resting lengths
What are functions of skeletal muscle?
-Maintain posture
-Produce skeletal movement
-Generate heat
-Protect internal organs
Cell Body (Soma)
Processing or “thinking” part of the neuron
Dendrite
Receives input from other neurons and carries it to the cell body
Axon
Single fiber that emerges from the cell body and propagates the nerve impulse, which is communicated to one or more cells
Astrocytes
-Regulate the environment around the neurons
-Contribute to the blood-brain barrier
-Regulate the inflammatory response to damage
Microglia
-Patrol the CNS, extending and retracting processes looking for areas of damaged, dead, or dying cells
-Phagocytize debris from the dead or dying cells and invading microorganisms
Oligodendrocytes
Myelinate axons in the CNS
Ependymal Cells
Have cilia that help move cerebrospinal fluid through the CNS
-Filter blood to make cerebrospinal fluid
Satellite Cells
Surround the cell bodies of neurons in the PNS, isolating them and protecting them from the surrounding tissue
Schwann Cells
Myelinate axons in the PNS
After a head injury, which glial cells would try to repair the damaged area?
Astrocytes & Microglia
Collections of neuronal cell bodies in the PNS are called _____, while collections of neuronal cell bodies in the CNS are called ______
ganglia; nuclei
What do the intercalated discs and gap junctions in cardiac muscle do?
form communication channels between adjacent cardiomyocytes, allowing cardiac muscle cells to contract in a wave-like pattern so the heart can work as a coordinated pump.
Fascicles
In the muscle: muscle fibers are organized into individual bundles in EACH skeletal muscle; sheath of connective tissue surrounds each individual fascicle called perimysium (mysium=muscle)
In the nerves: what axons are further bundled into within the nerve; surrounded by their own layer of fibrous connective tissue called perineurium (neurium=nerve)
Muscle fiber
a muscle cell, long and cylindrical, spans the entire length of the muscle within the fascicle; surrounded by a sheath of connective tissue the endomysium
Myofibrils
embedded in the muscle fiber; cylindrical structures extending the entire length of the muscle fiber
Epimysium
a sheath of dense, irregular connective tissue that surrounds each muscle
Perimysium
a sheath of connective tissue surrounding each individual fascicle
Endomysium
a sheath of connective tissue surrounding each individual muscle fiber
Myofilaments
-actin and myosin proteins organized into repetitive groupings that results in striations
Actin: thin filament
Myosin: thick filament
Sarcomere
actin and myosin are organized into repetitive groupings, and each unique grouping is called a sarcomere (the functional unit of the muscle fiber)
Neuromuscular junction
Where the motor neuron meets the muscle fiber; every skeletal muscle fiber must be innervated by a motor neuron in order to contract.
Motor unit
Single motor neuron and the muscle fibers it controls
All-or-none principle
when a motor neuron is stimulated, all muscle fibers in its motor unit will contract.
Slow oxidative fibers
A type of skeletal muscle fiber; Aerobic, endurance
Fast oxidative fibers
A type of skeletal muscle fiber; Anaerobic, instantaneous power
Atrophy
-reduction of muscle size, tone, and power
-can be caused by a lack of stimulation
-occurs with aging
Hypertrophy
-increase in muscle fiber size
-Results from repetitive stimulation of muscle fibers
-Both myofibrils and myofilaments increase in number, all resulting in the muscle increasing in size
Central Nervous System (CNS)
-consists of brain and spinal cord
-Nucleus, center
-Tract, column, etc…
Peripheral Nervous System (PNS)
-consists of all nervous tissue outside of the brain and spinal cord.
-Ganglion
-Nerve
Ganglion
collection of nerve cell bodies in the peripheral nervous system
Nucleus
a collection of neuronal cell bodies within the CNS
Nerve
bundle of axons in PNS
Tract
bundle of axons in CNS
Afferent
fibers that carry sensory information
Efferent
fibers that carry outgoing motor information
Sensory
carry signals from the outer parts of your body (periphery) into the central nervous system
Motor
carry signals from the central nervous system to the outer parts (muscles, skin, glands) of your body.
General somatic sensory
our sense of touch, pressure, pain, temperature, and proprioception
General somatic motor
voluntary movement by skeletal muscles
General visceral sensory
monitoring and sensing unconscious information primarily coming from our organs and glands
General visceral motor
involuntary movement of our cardiac and smooth muscle and secretion from glands
Synapse
the gap between two neurons; where neuronal communication occurs
Pseudounipolar neuron
have an axon that emerges from the cell body, but it splits so that the axon can extend along a very long distance. At one end of the axon are dendrites, and at the other end, the axon forms synaptic connections with a target
Bipolar neuron
These neurons have two processes, which extend from each end of the cell body, opposite to each other. One is the axon and one the dendrite. Bipolar cells are not very common.
Multipolar neuron
Multipolar neurons are all of the neurons that are not unipolar or bipolar. They are by far the most common neurons in the body. They have one axon and two or more dendrites (usually many more).
Converging circuit
postsynaptic neuron receives nerve impulses from several different sources; many inputs, one output
Diverging circuit
one nerve fiber branches and synapses with several postsynaptic cells
Myelin (sheath)
-a lipid-rich sheath that surrounds the axon and creates a myelin sheath that facilitates the transmission of electrical signals along the axon
-acts as insulation
Myelination
Process of wrapping an axon with a myelin sheath; Schwan cell
wraps around the axon in layers
Node of Ranvier
gaps in the myelin covering of an axon
Endoneurium
the loose CT that surrounds each individual axon
Perineurium
layer of fibrous connective tissue around individual fascicles (small groups of axons)
Epineurium
layer of fibrous connective tissue around the entire nerve
Fascicle
what axons are further bundled into within the nerve
Wallerian degeneration
process where a nerve fiber, when cut or damaged, begins to break down and deteriorate in the part of the axon that is furthest away from the cell body
Axon regeneration
After traumatic injuries, PNS axons can regenerate. Regeneration is possible if: Neuron cell body is intact, enough neurilemma remains, regeneration success is more likely if amount of damage is less extensive, distance between site of damage and structure it innervates is shorter
Skeletal muslce
an organ that consists of skeletal muscle fibers, blood vessels, nerve fibers, and connective tissue; sheathed in the epimysium
Small vs. Large motor unit
Small: one motor neuron supplies a small number of fibers in a muscle; this permits very fine motor control of the muscle
Large: one motor neuron supplies a large number of muscle fibers in a muscle; concerned with simple, or “gross” (large), movements.
