Homework 10-11 Anatomy

is the process in which action potentials in the nerve fiber lead to action potentials in the muscle fiber.

Excitation

What is the role of acetylcholinesterase?

It breaks down ACh, ending muscle stimulation.

Which of the following is/are a characteristic of skeletal muscle? Check all that apply.

Overlapping thin and thick filaments Overlapping thin and thick filaments Striations Overlapping myosin and actin proteins Excitability

Which of the following describes slow-twitch fibers?

They have a rich blood supply

1. Hundreds of mutations have been identified in RyR1 that contribute to multiple muscular diseases. Assume that a new mutation was discovered that causes this receptor to continually remain open. Based on what you know about the function of this receptor, how would you expect this new mutation to impact contraction?

This mutation will increase levels of calcium in the sarcoplasm, which will induce continued muscle contraction.

____________ moves back into position, blocking active sites, which prevents more contraction.

Tropomyosin

Which of the following is/are true regarding muscular strength and conditioning? Check all that apply.

Weight lifting does not increase the number of muscle fibers in a particular muscle exercised. Blood capillary density will increase in slow-twitch fibers in response to training for a marathon. Long-term resistance training will increase the number of myofibrils in a particular muscle exercised.

1. Thin filaments connect to and extend from either side of a __________. These thin filaments are composed largely of the myofilament __________.

Z disc; actin

3. If there was a high concentration of acetylcholine within the synaptic cleft, but little to no response at the motor end-plate, you would expect __________ to be the responsible neuromuscular-blocking agent.

curare

In smooth muscle, thin filaments are anchored to structures called ____________ .

dense bodies

The membrane ____________ , or becomes less negative.

depolarizes

2. Rigor mortis occurs after death because __________.

detachment of cross bridges does not occur due to the lack of ATP

Patients with this disease cannot synthesize the muscle protein ____________ , which is located just deep to the ____________ .

dystrophin, sarcolemma

Muscles can stretch and, when released, return to their original, shorter length. This property is referred to as ____________ .

elasticity

When an ion channel opens in a sarcolemma, ions flow across the membrane, altering the potential. These cells are said to be

electrically excitable

The connective tissue that surrounds each muscle fiber is called the ____________ .

endomysium

Also known as responsiveness, ____________ is a characteristic of all cells but more highly developed in muscle and nerve cells.

excitability

1. The presence of calcium in the sarcoplasm is directly responsible for __________.

exposing the binding sites on actin

Skeletal muscles can stretch up to three times their contracted length. This is called ____________ .

extensibility.

Complete tetanus of a muscle happens regularly in the human body.

false

It causes muscles to degenerate, weaken, and gradually be replaced with ____________ and scar tissue.

fat and scar tissue.

The underlying cause of this disease is

gene mutation.

When all nerve fibers are stimulated, an increase in stimulus strength will produce no ____________ in muscle tension.

increase

2. If it were possible to move the terminal cisternae further away from the T-tubules, it would __________.

interfere with the signal required for the release of calcium from the sarcoplasmic reticulum

What type of contraction involves the development of tension but no change in length?

isometric

Neither higher or lower in vo2

lactic acid accumulation central fatigue weight training

Increase with Anaerobic Resistance Training (Glycolytic and Phosphagen)

lactic acid processing, muscle size, myofibril size and number

Aerobic Respiration Supported by Cardiopulmonary Function

marathon running , jogging on the beach

The difference in charge created by the ECF ions and the ICF ions is called the ____________ .

membrane potential

Membrane potential is measured in

millivolts

Increase with Aerobic Exercise Training (Glycolytic and Phosphagen) Mitochondrial density Mitochondrial density

mitochondrial density, long term fatigue resistance, blood volume and red blood cell count. muscular density of blood capillaries

4. The antidote that holds the most promise to counteract the effects of tubocurarine is one that __________.

modifies acetylcholine receptors so that they bind acetylcholine stronger than tubocurarine

The type of smooth muscle cells known as ____________ are found in arrector muscles and in the iris of the eye.

multiunit

If an appropriate force is applied, the ____________ returns to its resting length.

muscle fiber

Each myofibril is made of up of several

myofilaments

1. Botulinum toxin causes muscle paralysis because __________.

no acetylcholine enters the synaptic cleft

2. Acetylcholine causes an end-plate potential by triggering the __________.

opening of sodium channels

Chemical Stimulation

oxytocin stimulates the myometrium to contract during child birth

Autonomic Nerve Fibers

parasympathetic nerves secrete acetylcholine which stimulates gastrointestinal motility

Glycogen-Lactic Acid System

pathway from glycogen to lactic acid, produces enough ATP for 30-40 seconds of maximum activity

A cell membrane is ____________ when there is a higher concentration of cations on one side and a higher concentration of ____________ on the other.

polarized, anions

Sodium ion channels close, but ____________ channels remain open. Loss of that ion ____________ the membrane.

potassium ion, repolarizes

There is then a rapid fluctuation in membrane voltage at the motor end plate, called the end-plate ____________ .

potential

Acetylcholine dissociates from its ____________ and is broken down enzymatically.

receptor

Facial wrinkles, such as glabellar or "frown" lines, appear with aging as a result of natural, repetitive muscle contractions. Botox® helps alleviate the appearance of these wrinkles by __________.

relaxing the facial muscles that cause the wrinkles

The specific name for a muscle fiber's plasma membrane is the ____________ .

sarcolemma

Autorhythmicity

sarcolemmas of the small intestine spontaneously depolarize resulting in wave like patterns of smooth muscle contractions

In a resting muscle fiber, a ____________ is normally 2.0 to 2.5 micrometers long.

sarcomere

Terminal cisternae are a structural feature of the organelle called the ____________

sarcoplasmic reticulum

Ion channels open in the plasma membrane, and ____________ diffuse into the ____________ .

sodium ions, ICF

A muscle cell is ____________ by a neurotransmitter from a motor neuron.

stimulated

The more motor units excited, the ____________ the contraction.

stronger

Phosphagen System

supplies energy very quickly and is the primary source of energy for very high-intensity exercise

1. Acetylcholine (ACh) is released from motor neurons and enters the __________.

synaptic cleft

This is the optimum length for producing maximum ____________ when the muscle contracts.

tension

In smooth muscle, the majority of the calcium ions come from ____________ .

the extracellular fluid.

Stretch

the presence of food distends the stomach wall resulting in contraction of the smooth muscles

If a muscle fiber is overly contracted, the ____________ filaments butt against the Z discs.

thick filaments

Conversely, if the muscle fiber is overly stretched, there is not enough overlap between the thick and ____________ myofilaments.

thin myofilaments

When stimuli reach or exceed ____________ , they excite more motor units.

threshold

Visceral smooth muscle is also known as ____________ smooth muscle.

unitary

Enlargements, or swellings, called ____________ contain neurotransmitters and are found along the length of autonomic neurons that activate smooth muscle.

varicosities

Isometric Contraction

A man holds open a door for his date, during this contraction tension is building in the series elastic elements, happens weightlifter pulls on a weight

Isotonic Contraction

A sprinter leaves the starting block, A mother lowers infant into a crib

2. Myosin heads directly use __________ to transition to their __________ conformation, which enables them ready to bind to actin.

ATP; energized

Which of the following is/are true about the functions of cardiac muscle? Check all that apply.

Cardiac muscle almost always utilizes aerobic respiration to obtain energy Cardiac muscle secures some of its calcium ions from the sarcoplasmic reticulum Autorhythmicity cells allow the myocytes to contract consistently and regularly, efficiently pumping blood from the chambers.

Which of the following is/are a functional requirement of cardiac muscle tissue? Check all that apply.

Cardiac muscle fibers must be able to contract without nervous stimulation. Cardiac muscle must be independent of conscious control. Cardiac muscles contract in unison.

Myasthenia gravis results when the body's immune system attacks ACh receptors, and muscle fibers become less sensitive to ACh. Which of the following might be a potential treatment?

Cholinesterase inhibitor

Doctors diagnosed the boy with the congenital muscle disease called

Duchenne muscular dystrophy.

Therefore, if the thick and thin filaments do not overlap, very few ____________ are formed.

cross-bridges

Relaxation Phase

-calcium levels in the sarcoplasm fall-myosin releases thin filaments-muscle tension declines

Malathion is a cholinesterase inhibitor that inhibits AChE. What effect would this have on muscle contraction?

Spastic paralysis

In a muscle fiber, the ____________ is adjacent to the terminal cisternae, so the action potential can stimulate calcium ion channels.

T tubule

Relaxation begins when nerve signals stop stimulating the synaptic knob and ____________ release ceases.

acetylcholine

The ions stimulate the release of ____________ into the synaptic cleft.

acetylcholine

Areas of the sarcolemma near the motor plate have gates that open, moving ions, which causes the ____________ potential that excites the muscle fiber.

action

The process just described is called a(n) ____________ .

action potential

The pump mechanism that maintains the resting membrane potential is an example of

active transport

Temperature

arrector pili muscles contraction causing hairs to become erect and goose bumbs to form skin

Results in Higher V0₂max

being a male, training for a marathon

Results in Lower V0₂max

being sedentary, getting older, being female

Active transport pumps in the SR move ____________ ions back into the cisternae.

calcium

The process begins with a nerve signal stimulating a voltage-gated ____________ ion channel to open, allowing the ions to enter the axon terminal.

calcium

In smooth muscle, Ca²⁺ binds to ____________ which then activates the enzyme ____________ leading to the phosphorylation of myosin.

calmodulin , myosin light chain kinase

The ability to carry an electrical charge along the cell is called ___

conductivity

Muscles can pull bones closer to one another and increase the motility of some organs. This is due to the property of ____________

contractility

Subthreshold stimuli produce no muscle

contraction