Exam 2 Exercise Physiology

What is repolarization?

Repolarization is the phase in which the membrane potential of a cell returns to its resting state, following depolarization and the generation of an action potential.

What is repolarization?

Repolarization is the return of a neuron's membrane potential to resting potential after depolarization.

Why is the resting membrane potential negative?

Resting membrane potential is negative because there are more negative ions inside the neuron than outside.

What is resting membrane potential?

Resting membrane potential is the electrical charge difference that exists across the membrane of a resting neuron, which is around 70 millivolts.

DHP(Ryadine receptor) does what?

Talks to the SR for calcium to be released to go attach to troponin to cause muscle contraction

What is an A band?

The A band is a dark-colored band that contains thick filaments and includes the M line and overlapping thick and thin filaments.

What is the A-band?

The A-band is the region of the sarcomere where thick filaments overlap with thin filaments.

Depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

What is the A-band?

The region of the sarcomere where thick and thin filaments overlap to give it a dark appearance.

What is the resting membrane potential?

The resting membrane potential is the electrical charge difference between the interior and exterior of a neuron at rest.

. What is a sarcomere?

The sarcomere is the basic unit of muscle contraction. It consists of overlapping thick and thin filaments between two Z discs.

What is the role of the sarcoplasmic reticulum in muscle contraction?

The sarcoplasmic reticulum stores and releases calcium ions during muscle contraction, allowing them to bind to regulatory proteins on the thin filaments and initiate the contraction process.

What are thick filaments?

Thick filaments are made up of myosin protein and are responsible for generating the force of muscle contraction.

What are thin filaments?

Thin filaments are made up of actin protein and are responsible for sliding past thick filaments during muscle contraction.

Dendrites

Transmits action potentials toward a nerve cell body.

Bike Chain =

Tropomyosin

What is the role of tropomyosin in muscle contraction?

Tropomyosin is a regulatory protein that covers the binding sites on actin filaments, preventing myosin heads from interacting with them in the absence of calcium ions.

What is the name of the regulatory protein that covers the binding sites on actin when the muscle is at rest?

Tropomyosin.

Bike lock key=

Troponin

Calcium is attracted to what?

Troponin

What is the name of the protein that binds to tropomyosin and moves it away from the binding sites on actin?

Troponin.

What happens when a stimulus changes the permeability of a neuron's membrane?

When a stimulus changes the membrane permeability of a neuron, sodium enters the cell and depolarizes it.

What happens when depolarization reaches a threshold?

When depolarization reaches the threshold, more sodium gates open and an action potential is triggered.

What is the lactate threshold?

When resting lactate values begin to increase above baseline

What is force gradation also known as motor unit recruitment

Force gradation is how skeletal muscles vary the amount of force produced by activating different motor units of varying sizes.

Afferent

From Body to Brain - Inhibitory resposnse

Efferent

From Brain to Body -You make it happen

Muscle Spindle

Functions as a length detector in muscle.

What are the nodes of Ranvier?

Gaps in the myelin sheath Allows for a slight pause. (Without muscles only know how to go one time)

What is the name of the area where actin and myosin overlap in a sarcomere?

A band.

What is a fascicle?

A fascicle is a bundle of muscle fibers surrounded by perimysium.

The PNS is divided into ______ and ______ divisions.

Afferent and Efferent

What is an action potential?

An action potential is a nerve impulse that occurs when depolarization reaches threshold.

What covers axons and what are the gaps between them called?

Axons are covered by Schwann cells, and the gaps between them are called nodes of Ranvier.

Golgi Tendon Organ

Continuously monitor the tension developed during muscular contraction and serve as safety devices that help prevent excessive force during muscle contractions.

Golgi Tendon organ (GTO)

In where muscle fibers insert into the tendons of skeletal muscle; Sensitive to changes in muscular tension and rate of tension change. Efferent Inhibitory response

What sensory feedback does the nervous system need to properly control skeletal muscle movements?

Information about tension and length of the muscle.

Peripheral fatigue

Inhibility of calcium to be released for muscles contraction.

What are inhibitory neurotransmitters?

Inhibitory neurotransmitters cause hyperpolarization of the membrane, which is called an inhibitory postsynaptic potential (IPSP).

What are T-tubules?

Invaginations of the sarcolemma that allow for rapid transmission of action potentials.

What is muscle relaxation, and how is it achieved?

Muscle relaxation occurs when calcium ions are pumped back into the sarcoplasmic reticulum, causing tropomyosin to cover the actin binding sites and preventing further interaction with myosin heads.

What sensory organ provides information about the relative length of the muscle?

Muscle spindle.

What are myofilaments?

Myofilaments are the protein structures within muscle cells responsible for contraction.

The peripheral nervous system includes the nerves where?

Outside the central nervous system.

muscles spindles

receptors sensitive to change in length of the muscle and the rate of that change Afferent You cause it in muscle belly Excitatory

Isomertic contraction

tension within the muscles but the length remains the same

myosin heads attach to

binding sites on thin filaments (Actin)

Overshoot=

+30mV

Threshold =

-55 mV

What mV is threshold?

-55mV

Cells are composed of what three regions?

Cell Body, Dendrites, Axon

If we do not have enough energy where does central fatigue happen?

Cell body

What are thin filaments?

Composed of actin and slide past the thick filaments to generate muscle contraction.

What are thick filaments?

Composed of myosin and responsible for generating force.

What are myofibrils?

Contractile units of muscle fibers.

100ml of AP for what to occur?

Contraction

If you do not have calcium in the SR what happens?

Contraction Dies

What is the myelin sheath?

Covers the axon of some neurons and helps speed neural impulses (kinda like a Enzyme)

Why is the NMJ important?

Crucial for the nervous systems control over muscle contraction and can be affected in neuromuscular disorders.

What is the Node of Ranvier?

Exposed section along the myelin sheath of a nerve cell that helps to increase the speed and efficiency of nerve impulses.

What is fascia?

Fascia is connective tissue that separates and supports individual muscles.

What is the name of the area where only actin is present in a sarcomere?

I band.

100 AP is required for what?

Muscle Contraction

Sliding filament theory steps

Nerve impulse is sent to muscle fiber. Calcium ions are released from the sarcoplasmic reticulum. Calcium ions bind to troponin, causing tropomyosin to move and expose the myosin binding sites on the actin filaments. Myosin heads bind to the actin filaments, forming cross-bridges. Myosin heads pivot and pull actin filaments towards the center of the sarcomere, shortening muscle fiber and producing force. ATP provides energy to allow myosin heads to detach from the actin filaments and reset for another power stroke. When nerve impulse stops, calcium ions are pumped back into sarcoplasmic reticulum, causing myosin binding sites to become covered by tropomyosin again and the muscle fiber relaxes.

The _____________ is the body's means of perceiving and responding to events in the internal and external environments

Nervous system

Repolarization

Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.

What is the cytoplasm of a myofiber called?

Sarcoplasm.

What is the name of the network of tubules that surrounds each myofibril?

Sarcoplasmic reticulum.

What are muscle mechanoreceptors?

Sensory receptors in skeletal muscle that respond to mechanical changes in muscle, including muscle spindles and Golgi tendon organs.

What is proprioceptive sensations?

Specialized receptors located in the muscles, tendons, and joints that provide information about the body's position, movement, and spatial orientation.

What is the role of the sarcoplasmic reticulum?

Stores and releases calcium ions necessary for muscle contraction.

What is the H-zone?

The H-zone is the central region of the sarcomere where only thick filaments are present.

What is the endomysium?

The endomysium is a layer of connective tissue that surrounds each individual muscle fiber within a fascicle.

APMHR

220-age age predicted maximal heart rate

What is the epimysium?

The epimysium is the outermost layer of connective tissue that surrounds the entire skeletal muscle.

What is an action potential?

An action potential is a brief electrical signal that travels down the ne uron.

What is the sliding filament theory?

A model of muscle contraction that explains how muscle fibers generate force.

What is a motor unit?

A motor neuron and the muscle fibers it controls.

What are excitatory neurotransmitters?

Excitatory neurotransmitters increase a neuron's permeability to sodium and result in excitatory postsynaptic potentials (EPSPs).

What are sarcomeres?

Smallest units of muscle contraction.

What is the I-band?

The I-band is the region of the sarcomere where only thin filaments are present.

eccentric contraction

muscle lengthens

1 motor stimulating 10 muscles fibers=

Fine motor skills like eye sight

Where are the Go/No-Go spots?

First go no go is in the cell body. Second is the calcium being released from the SR

What is the name of the motor neuron that stimulates muscle contraction?

Motor unit.

What is skeletal muscle made of?

Muscle fibers.

How is muscle force generated?

Muscle force is generated by the number of cross-bridges formed between myosin and actin filaments and the rate at which they cycle.

The nervous system is divided into what two major divisions?

(1) The central nervous system and (2) The peripheral nervous system

The magnitude of the resting membrane potential is primarily determined by what two factors:

(1) The permeability of the cell membrane to different ions and; (2) The difference in ion concentrations between the intracellular and extracellular fluids

RMP=

-70mV

Undershoot=

-85mV

How long is the action potential?

1^-3 milliseconds long

What is a motor neuron?

A nerve cell that connects with muscle fibers to form a motor unit.

What is troponin?

A protein that binds to calcium ions and triggers muscle contraction.

What is tropomyosin?

A protein that covers the binding sites on actin to prevent muscle contraction in the absence of calcium ions.

What is a sarcomere?

A sarcomere is the basic functional unit of muscle contraction, consisting of overlapping thick and thin filaments.

What is the sarcoplasmic reticulum?

A specialized endoplasmic reticulum that stores calcium ions.

Contraction requires ___ & ______

ATP and calcium

What is ATP, and how is it involved in muscle contraction?

ATP is the primary source of energy for muscle contraction, and it is used by myosin heads to release and reattach to actin filaments.

What is the name of the neurotransmitter that is released at the neuromuscular junction?

Acetylcholine.

What are the two main proteins that make up a sarcomere?

Actin and myosin.

What are the thin filaments in a sarcomere made of?

Actin.

The central nervous system includes the _____ and the _______.

Brain, spinal cord

What is the role of calcium ions in muscle contraction?

Calcium ions bind to regulatory proteins on the thin filaments, allowing the myosin heads to interact with actin and initiate muscle contraction.

Axon

Carries the electrical message (called action potentials) away from the cell body toward another neuron or organ.

Afferent Fibers

Carry neural information back to the central nervous system.

Efferent Fibers

Carry neural information from the central nervous system to the periphery.

action potential cannot talk to what?

Chemical

What is depolarization in the cell?

Depolarization is when the cell becomes more positive, which can lead to an action potential.

reason for the skeletal muscle contractions to stop

Die Want it to stop Run out of calcium

What is excitation-contraction coupling? (ECC)

Electrical signal, or action potential, in a muscle cell triggers the release of calcium ions from the sarcoplasmic reticulum, leading to the contraction of the muscle fiber.

What is the pre synaptic terminal?

End of an axon that releases neurotransmitters into the synaptic cleft to signal to the postsynaptic neuron or target cell.

What sensory organ provides information about tension in the muscle?

Golgi tendon organs.

1 motor stimulating 1000 of fibers =

Gross motor skill like walking

What are myofibers?

Long cells with multiple nuclei.

Alpha motor neuron controls what?

Motor Units

How do myosin and actin interact in muscle contraction?

Myosin heads interact with actin filaments to form cross-bridges, which pull the thin filaments towards the center of the sarcomere.

What are the thick filaments in a sarcomere made of?

Myosin.

At rest, all cells (including neurons) are ________ charged on the inside of the cell with respect to the charge that exists outside the cell.

Negatively

What is the name of the point where the motor neuron meets the muscle fiber?

Neuromuscular junction.

What is the all or none law?

Once the threshold is reached, an action potential will fire at full strength or not fire at all.

What is the plasma membrane around a myofiber called?

Sarcolemma.

What is skeletal muscle tissue composed of?

Skeletal muscle tissue is composed of muscle fibers, nerve tissue, blood, and various connective tissues including fascia, epimysium, perimysium, endomysium, and basal lamina.

Motor Untis do what?

Stimualte muscle

What do motor neurons do?

Stimulate skeletal muscle cells to contract through the NMJ.

Contact points between an axon of one neuron and the dendrite of another neuron are called what?

Synapses

What are synapses?

Synapses are junctions where neurons communicate with each other.

What is synaptic transmission?

Synaptic transmission occurs when a neurotransmitter is released from a presynaptic neuron and binds to a receptor on the postsynaptic membrane.

What is an H zone?

The H zone is a light-colored band that contains only thick filaments and includes the M line and the area between overlapping thick filaments.

What is an I band?

The I band is a light-colored band that contains thin filaments and includes the Z disc and the area between overlapping thick and thin filaments.

What is an M line?

The M line is a dark line that runs down the center of the sarcomere and anchors the thick filaments in place.

What is a Z disc?

The Z disc, also known as a Z line or Z band, is a thin, dark line that marks the boundary between adjacent sarcomeres.

What is the basal lamina?

The basal lamina is a layer of protective tissue around each muscle fiber.

What is a sarcomere?

The basic unit of muscle contraction composed of thick and thin filaments.

Cell Body

The center of operation for the neuron

What is the H-zone?

The central region of the sarcomere where there are only thick filaments.

What is the power stroke in muscle contraction?

The power stroke is the movement of the myosin head as it pulls the actin filament towards the center of the sarcomere.

What is the sarcolemma?

The membrane surrounding muscle cells.

What is myelin Sheath?

The myelin sheath is a protective covering that surrounds the axons which speed up electrical signals to move more efficiently along the axon.

What is the perimysium?

The perimysium is a layer of connective tissue that surrounds individual bundles of muscle fibers called fascicles.

What is the neuromuscular junction (NMJ)?

The site where a motor neuron and muscle cell meet to transmit signals.

What is the sliding filament theory?

The sliding filament theory is the mechanism by which muscles contract and generate force.

What is the synaptic cleft?

The space between the end of the motor neuron and the sarcolemma.

What are the three layers of connective tissue in skeletal muscle?

The three layers are epimysium, perimysium, and endomysium.

What are the three parts of a neuron?

The three parts of a neuron are the cell body, dendrites, and axon.

What are the two types of myofilaments?

The two types of myofilaments are thick filaments (myosin) and thin filaments (actin).

Concentric

muscle shortens

What is rigor mortis?

stiffening of muscles after death