muscles Flashcards
Main function of skeletal muscles
movements of body
three types of contractile cells of body
skeletal, cardiac, smooth muscle cells
Skeletal
Elongated
muscle cells are voluntary
Striated
Cardiac
branching
involuntary
striated
Smooth Muscle
Spindle shaped
involuntary
not striated
Endomysium
wrapping around a single cell
aponeurosis
broad flat sheet connecting muscles to bones or other muscles
perimyseum
wrapping around fascicle
Epimyseum
wrapping around an entire muscle
Fascia
layers beneath the skin that bind muscles into groups in a body region
Tendon
Band or cord that connects muscle to bone
Functions of connective tissue wrappings around and within a skeletal muscle?
Insulation, free movement of muscles, carries nerves, blood vessels, fills spaces between muscles
Single Muscle Cell is called:
Fiber–basic unit of structure and function for a muscle
Levels of organization from smallest to largest
muscle fascicle fiber myofibril filament
Sarcoplasmic Reticulum
Interconnecting tubules of endoplasmic reticulum that surround each myofibril
Sarcolemma
Plasma membrane of muscle cell
Sarcoplasm
Muscle cell cytoplasm
Sarcomere
Region of myofibril between two Z lines
Myofilament
Bundle of contractile proteins, arranged into sarcomeres
Fiber
Whole muscle Cell
Myofibril
threadlike contractile organelle within a muscle cell
T-Tubules
An invagination of sarcolemma that projects deep into the muscle cells interior.
Muscle action potential travels through it
Thick filament is made up of:
Myosin
Thin filament is made up of:
Actin
Regulatory proteins in the thin filament are:
Tropomyosin and Troponin
Terminal Cisternae
Sac-like regions of the sarcoplasmic reticulum that contain calcium ions
Mitochondrion
Sites of ATP synthesis
Triad
A group of one T tubule lying between two adjacent terminal cisternae
I Band
Contains only thin filaments
A Band
Contains only thick filaments
H Zone
Contains both thin and thick filaments
Aerobic Exercise
requires warm up
sustained for a long period of time
used at rest and endurance (ME!)
Anaerobic Exercise
Initiated quickly
rapid fatigue
short, high intensity exercise
Twitch
brief single contraction in response to a single stimulus
Tone
Small amount of tension in the muscle due to weak contractions of motor units
Tetanus
Fusion of twitched to form a smooth sustained contraction
Isotonic contraction
Muscle shortens in length/tension remains same during contraction
Produces movement
Isometric Contraction
muscle length remains about the same/muscle tension increases during contraction
maintain upright posture
Eccentric Contraction
Muscle lengthens during contraction due to opposite outside force (weights)
Electrical Excitability
Ability to respond to certain stimuli by producing electrical signals
Conductivity
Signal is allowed to travel
How are electrical excitability and conductivity essential for neuron function?
They allow the neuron to generate on action potential and then transfer to other cells
Motor Unit
Consists of somatic motor neuron + all the skeletal muscle fibers it stimulates
Motor unit recruitment
process where the number of active motor units increases
Axon
propagates nerve impulses toward another neuron, a muscle fiber or a gland cell. (threadlike)
Conduct and transmit signals to other cells and at the synapse
One per neuron, long, have collaterals (branches)
Cell body
contains nucleus surrounded by cytoplasm
Dendrites
(little trees) Receive info from other cells or outside source (neutron)
Receive signals at the synapse
Many, short and branched
Myelin Sheath
Multi-layered lipid and protein covering around some axons
Insulates and increases speed of nerve impulse conduction
What type of glial cell form it in the neurons of the PNS?
Satellite cells
What type of glial cell form it in neurons of the CNS?
Neuroglia (glue)
Bipolar Neuron
Two processes extending from cell body
limited distribution
Unipolar Neuron
One process extending from cell body Sensory Neurons (carries incoming info to brain/spinal chord
Multipolar Neuron
Many interneurons in brain and spinal chord
one axon, many dendrites
motor neurons
Motor Neurons
Conduct electrical signals away from CNS to muscles or glands OUTGOING
Efferent neurons
Makes up the PNS
Sensory Neurons
Conduct electrical signals from receptors to the CNS INCOMING
Afferent neurons
Makes up the PNS
Interneurons
Conducts electrical signals within the CNS
Found ONLY in CNS
Conducts signals between sensory and motor neurons
Steps of muscle contraction
- Myosin heads hydrolyze ATP and become reoriented and energized
- Myosin heads bind to actin, forming cross-bridges
- Myosin cross-bridges rotate toward center of sarcomere (power stroke)
- As myosin heads bind to ATP, the cross-bridges detach from Actin.
What 2 substances must be present for cross bridge cycling to continue
ATP and Calcium
What is the function of Calcium Ions in a contraction
triggers exposure of binding sites on actin
What is the function of ATP in a contraction?
Binds to cross bridge, energizes myosin heads. Causes the cross bridge to release from Actin
What is the function of Cross-bridges?
Flex, pulling the filament inward toward the sarcomere
The 3 steps in muscle contraction that require ATP are:
- Active transport of calcium ions into the SR.
- Energizes the power stroke of the cross bridge
- Disconnects the cross bridge from the binding site on the actin at the end of the power stroke.
What is “membrane potential”?
Electrical potential difference (voltage) across membrane
What is “polarized”?
Separation of Charges across the membrane.
Passive or “leak” channels
Open and close randomly but are mostly open
Voltage-gated channels
open with electrical stimulus (voltage change)
Chemically gated (ligand gated) channels
open when specific molecule binds to it. (bending, pressure.)
Characteristics of Na+
Higher concentration along the outside of the cell membrane
tends to diffuse INTO the cell, but only to a very limited extent, due to few leak channels
moved OUT of the cell by the Na+-K+ pump
Characteristics of K+
Higher concentration along the INSIDE of the cell membrane
tends to diffuse easily OUT of the cell, due to many leak channels.
Moved INTO cell by the Na+-K+ pump
Graded potential
Produced when Ligand gated channels open
action potential
function of Voltage gated channels in the membrane of axons and neurons (Traveling signal of nervous system)
Depolarization
membrane potential becomes smaller; made more positive
Hyperpolarization
membrane potential becomes larger
Re polarization
Membrane potential is RESTORED to it’s resting state
A change from -70mV to -85mV is a:
Hyperpolarization
A change from -70 mV to -65 mV is a
depolarization
Depolarizations are:
Excitatory
Hyperpolarizations are:
inhibitory
“All or None” principal is:
Once threshold is reached, all action potentials are the same size.
Myelinated axons conduct action potentials:
FASTER than unmyelinated axons
Axons of larger diameter conduct action potentials:
FASTER than smaller ones
Saltatory conduction occurs in
MYELINATED axons
List 3 ways in which neurotransmitter molecules can be removed from the synaptic cleft
1) Diffusion
2) Enzymatic degradation
3) Uptake of cells
Steps in the synaptic transmission
1–action potential arrives at axon terminal of pre synaptic neuron
2–Voltage-gated Ca^2+ channels open in the axon terminal
3–Calcium diffuses into the axon terminal from the ECF
4–Neurotransmitter is released by exocytosis
5–Neurotransmitter diffuses across the synaptic cell
6–Neurotransmitter molecules bind to receptor molecules in the post-synaptic membrane
7–Ion channels in the post-synaptic membrane are opened
8–a post-synaptic potential is produced
9–Neurotransmitter is removed from the synaptic cleft
Components of Reflex Arc
1--Sensory Receptor 2--Sensory Neuron 3--Integrating Center 4--Motor Neuron 5--Effector
