Nerve, Muscle, Synapse Lecture 5 Flashcards
_______ neurons are always excitatory
Afferent = release glutamate
What are the three types of muscle?
Smooth
Cardiac
Skeletal
_____ muscle is found in all organs of the body and their contractions act to reduce the size of structures
Smooth muscle is found in all organs of the body and their contractions act to reduce the size of structures
What are four functions of smooth muscle?
Voluntary or involuntary?
- Regulates flow of blood through arteries
- Moves food through GI tract
- Expels Urine from the bladder
- Regulates the flow of air through the lungs
Involuntary
Cardiac Muscle:
- _____ muscle found in the walls of the ______
- Propels blood into the _____ and through the _____ of the circulatory system
- _______ control
Cardiac Muscle:
- striated muscle found in the walls of the heart
- Propels blood into the heart and through the blood vessels of the circulatory system
- involuntary control
_______ muscle is attached to the skeleton and is also called striated muscle
skeletal muscle is attached to the skeleton and is also called striated muscle
Skeletal muscle is under _______ control
voluntary
Each muscle cell is surrounded by _______
endomysium
_______ surrounds each muscle fiber (cell) and electrically isolates the muscle fibers from one another
endomysium surrounds each muscle fiber (cell) and electrically isolates the muscle fibers from one another
Skeletal muscles are electrically insulated from each other by ______
endomysium
In order for skeletal muscle cells to contract, each cell must be stimulated by a process of a ________
Motor Neuron
Motor neurons leave the spinal cord through the:
Ventral Horn
Each ______ neuron innervates a number of muscle cells = impossible to contract just one muscle cell
Each efferent neuron innervates a number of muscle cells = impossible to contract just one muscle cell
A motor neuron, its axon and all the muscle fibers it activates makes up the:
Motor unit
The ______ is the functional unit of the motor system and represents the SMALLEST increment in force that can be generated
Motor Unit
What is the neuromuscular junction
Where the nervous system meets the muscle
Neuromuscular junction we have ______-gated chemical synaptic transmission with the post-synaptic cell being the: _____
Neuromuscular junction we have directly-gated chemical synaptic transmission with the post-synaptic cell being the: muscle cell (fibre) HAS ONLY ONE SYNAPSE
The region of the muscle fibre plasma membrane that lies directly under the terminal portion of the axon is called:
the motor end plate
What is the neurotransmitter used by the efferent (motor) neurons?
Acetylcholine - excitatory
Acetylcholin binds to ______ receptors
Ionotropic receptors
Ionotropic Receptors: receptors that form _______following the binding of a ______; “______-_______”
Ionotropic Receptors: receptors that form ion channels following the binding of a ligand; ligand-gated ion channels
When acetylcholine binds to its receptors it generates a ________of the post-synaptic cell (muscle cell) = opens voltage gated ___ channels
When acetylcholine binds to its receptors it generates a local depolarization of the postsynaptic cell (muscle cell) = opens voltage gated Na+ channels
What are 3 Differences between synaptic transmission at a neuromuscular junction and a central synapse?
- One AP in motor neuron generates one AP in muscle cell (summation required in CNS; no summation in muscle)
- Each muscle fibre is only innervated by one presynaptic cell
- No inhibitory transmitters: Only acetylcholine = always excitatory
The extracellular space is ______ charged with respect tot he intracellular space
The extracellular space is Positively charged with respect tot he intracellular space
The ______ of muscle are extracellular space = positively charged with respect to intracellular space
The Transverse Tubule (T-tubule) of muscle are extracellular space = positively charged with respect to intracellular space
As sodium rushes into the muscle cell it generates an ____
Action Potential
The ______ surrounds each myofibril within the muscle cell. It is loaded with calcium
Sarcoplasmic Reticulum
The action potential causes the release of Ca2+ from the _______
Sarcoplasmic reticulum
_______ is the neurotransmitter used at the neuromuscular junction
Acetylcholine
How many neuromuscular junctions are there per muscle cell?
ONE
Compare excitation-contraction coupling in Skeletal muscle to Cardiac Muscle:
- Cardiac muscle:
- L-type Ca2+ channel (modified dihydropyridine receptor)
- voltage-gated Ca2+ channel
- Calcium binds to Ryanodine receptor (in SR) - ryanodine receptor opens = flows out of sarcoplasmic reticulum
- No physical coupling
- Calcium-dependent calcium release
- L-type Ca2+ channel (modified dihydropyridine receptor)
- Skeletal muscle
- Physical coupling between dihydropyridine receptor (DHP) and ryanodine receptor via foot process
- opens calcium channel in sarcoplasmic reticulum
Myofibrils are comprised of the contractile elements:
Actin and Myosin (protein filaments)
The sarcomere is bound on either side by ____ lines
Z
What is the H zone?
Gap between the thick filaments in the sarcomere
Although the sarcomere shortens, the length of each _____ does not change. However, the width of the ___ zone changes
Although the sarcomere shortens, the length of each myofilament does not change. However, the width of the H zone changes
During muscle contraction, the sarcomere _____ and the H-zone becomes _____
During muscle contraction, the sarcomere shortens and the H-zone becomes narrower
Events at the Neuromuscular Junction
- The neurotransmitter _______ contained within vesicles is released via ________ into the ______. Additionally, ____ ions are pumped out of the axon terminal
Events at the Neuromuscular Junction
- The neurotransmitter acetylcholine contained within vesicles is released via exocytosis into the synaptic cleft. Additionally, Ca2+ ions are pumped out of the axon terminal
Events at the Neuromuscular Junction
- The depolarization of the ________ initiates an action potential which propagates along the ______ in all directions and down the ______
Events at the Neuromuscular Junction
- The depolarization of the Motor End Plate initiates an action potential which propagates along the Sarcolemma in all directions and down the T-Tubules
Events at the Neuromuscular junction:
- Action potential causes the release of Ca2+ from the _______ into the cytosol
Events at the Neuromuscular junction:
- Action potential causes the release of Ca2+ from the terminal cisternae into the cytosol
