The Muscular System

Question 0

Skeletal muscle

Answer 0

Individual muscle fibers

Voluntary muscle

“Muscle” = multiple bundles of muscle fibers held together by connective tissue.

One of 3 major types of muscles: also cardiac and smooth muscle

Question 1

Muscular system

Answer 1

Series of muscles that moves the skeleton.

“Movers and stabilizers”

Question 2

Epimysium

Answer 2

A layer of connective tissue that is underneath the fascia and surrounds the muscle

Question 3

Bundles of muscle fibers

Answer 3

Broken down into layers from outer to innermost layer.

First bundle = actual muscle itself wrapped by putter layer of connective tissue called fascia

Question 4

Fascia

Answer 4

Outer layer or connective tissue that wraps the actual muscle itself

Fascia & emipysium connected to bone to help form muscles tendon

Question 5

Perimysium

Answer 5

The connective tissue that surrounds the fascicles

Question 6

Fascicle

Answer 6

Comes after the epimysium.

Wrapped by the perimysium

Question 7

Endomysium

Answer 7

The deepest layer of connective tissue that surrounds individual muscle fibers

Question 8

Connective tissue

Answer 8

Play vital role in movement

Allow forces generated by the muscle to be transmitted from the contractile components of muscle to bones.

Each layer of connective tissue extends the length of the muscle helping from the tendon

Question 9

Tendons

Answer 9

Connective tissues that attach muscle to a bone and proved an anchors for muscles to produce force.

Poor vascularity, slower repair and adaptation

Question 10

Sacrolemma

Answer 10

Plasma membrane that encases muscle fibers

Question 11

Muscle fibers & their contractile elements

Answer 11

Encased by sarcolemma & contain cell components such as cellular plasma (sacroplasma), nuclei, & mitochondria.

Have myofibrils that contain myofilaments - the actual contractile comments of muscle tissue. -> actin (thin filaments) & myosin (thick filaments)

Question 12

Sarcomere

Answer 12

The functional unit of the muscle, lies b/w two Z lines, that produces contraction (muscle contraction) containing actin and myosin

Question 13

Tropomyosin

Answer 13

Located on the actin filament and blocks myosin binding sites located on the actin filament, keeping myosin from starching to actin while the muscle is in a relaxed state

Question 14

Troponin

Answer 14

Located on the actin filament, provides binding sites for calcium and tropomyosin when muscle needs to contract

Question 15

Neural activation

Answer 15

Contraction of a muscle generated by neural stimulation

Communication link b/w the nervous and muscular system

Question 16

Motor unit

Answer 16

A motor neuron and all of the muscle fibers it connects with

Muscles divided into motor units

Either contract maximally or not at all

Question 17

Neurotransmitters

Answer 17

Chemical messengers that cross the neuromuscular junction (synapse) to transmit electrical pulses from
The nerve the the muscle.
Once released, they link with receptor sites on muscle fiber.
Once attatched, ACh stimulates the muscle fibers to initiate muscle contractions

Question 18

Neuromuscular junction

Answer 18

The point at which the motor neuron meets and individual muscle fiber.

This junction is actually a small gap b/w the nerve and muscle is called a “Synapse”

Question 19

Acetylcholine (ACh)

Answer 19

The neurotransmitter used by the neuromuscular system.

Question 20

Sliding filament theory

Answer 20

How thick and thin filaments within the Sarcomere slide past one another, shortening the entire length of the sacromere and thus shortening muscle and producing force.

1. A sacromere shortens as a results of the Z lines moving closer together (contracting)
2. The Z lines converge as the result of myosin heads attaching to the actin filament and asynchronously pulling (power strokes) the actin filament across the myosin, resulting in shortening of the muscle fiber.

Question 21

Excitation-Contraction Coupling

Answer 21

The process of neural stimulation creating a muscle contraction. Begin with neural activation and end up with sliding-filament theory through series of steps

Question 22

“All or Nothing” Law

Answer 22

Motor units cannot vary the amount of force they generate; either contract maximally or not at all.

If stimulus is strong enough to trigger an action potential, it will then spread through whole length of muscle fiber, if NOT strong enough, there will be NO action potential and no muscle contraction.

The overall strength of a skeletal muscle contraction will depend on the size of the motor unit recruiter (how many muscle fibers are contained in the unit) and the number of motor units that are activated at a given time. Size of motor units directly relates to the function of the muscle. Ex: precise movements = fewer motor units (eye) / large muscles = more motor units

Question 23

Type I muscle fibers

Answer 23

•Slow-twitch 
•More capillaries, mitochondria, and myoglobin. 
•"Red fibers"
• Increased oxygen delivery
• Smaller in size
• Less force produced 
• Slow to fatigue 
• long term contractions (stabilization & posture)
(sitting for extended time)

Slow -> fast

⚠️All muscles have a combo of slow and fast twitch fibers that will vary depending on function of muscle ⚠️

Question 24

Type II muscle fibers

Answer 24

* Fast - twitch * "white fibers" * Fewer capillaries, mitochondria, myoglobin * Decreased oxygen delivery * larger in size * more force produced * short term contractions (sprint) (force and power) • IIa & IIx ⚠️All muscles have a combo of slow and fast twitch fibers that will vary depending on function of muscle ⚠️

Question 25

Mitochondria

Answer 25

Transforms energy from food into ATP or cellular energy

Question 26

Myoglobin

Answer 26

Allows for improved delivery of oxygen.

Question 27

Type IIx

Answer 27

* low oxidative capacity (ability to use oxygen) | * fatigue quickly

Question 28

Type IIa

Answer 28

* higher oxidative capacity * intermediate-fast twitch fibers * use both aerobic and anaerobic metabolism almost equally to create energy

Question 29

Agonist

Answer 29

Muscles that act as prime movers (most responsible for particular movement) Ex: gluteus maximus is an agonist for hip extension

Question 30

Synergist

Answer 30

Assist prime movers during movement. | Ex: hamstring complex and the erector alone are synergist with the gluteus maximus during hip extension.

Question 31

Stabilizer muscles

Answer 31

Support or stabilize the body, where as the prime movers and the synergist a perform the movement patterns. Ex: transversus abdominis, internal oblique and multifidus (deep muscles in low back) stabilize the low back, pelvis, and hips (LPHC) during hip extension:

Question 32

Antagonist

Answer 32

Perform the opposite action of the prime mover. | Ex: the psoas (deep hip flexor) is antagonistic to the gluteus maximus during hip extension.

Question 33

The endocrine system

Answer 33

System of glands that secrete hormones into the blood stream to regulate bodily functions (mood, growth, development, tissue function, metabolism) Consists of host organs (glands), chemical messengers (hormones), and target (receptor) cells. "Endocrine" = hormone secreting

Question 34

Hormones

Answer 34

Hormones produced by the endocrine system affect virtually all forms of human function: • triggering muse contraction • stimulation protein and fat synthesis • activating enzyme systems • regulating growth and metabolism • determining how body responds to stress

Question 35

Endocrine glands

Answer 35

Hypothalamus, pituitary, thyroid and adrenal glands.

Question 36

Pituitary gland

Answer 36

"Master gland" -> controls the functions of the other glands. Located in brain 3 different sections/lobes - anterior, intermediate and posterior. Each lobe secretes specific types of hormones

Question 37

Thyroid glands

Answer 37

Produces hormones that regulate the rate off tabloids and affect the growth and rate of function of other systems in body.

Question 38

Adrenal glands

Answer 38

Secrete hormones such as corticosteroids and catecholamines, including cortisol and adrenaline in response to stress.

Question 39

Hypothalamus gland

Answer 39

Located in brain | Much control of hormone activity

Question 40

Carbohydrate

Answer 40

(glucose) is the primary energy source during vigorous exercise. Glucose is principal fuel for brain. Control of blood glucose is through pancreas which produces insulin and glucagon

Question 41

Insulin

Answer 41

Helps regulate energy and glucose metabolism. After eating, glucose enters the blood at the small intestine, causing a rise in blood glucose levels. As blood goes through pancreas, elevated levels of blood glucose trigger release of insulin. Circulating insulin binds with receptors of it's target cells (skeletal muscle or liver cells) and cell membrane becomes permeable to glucose. Glucose then diffuses out of blood stream into cell. = drop in blood glucose levels. Thus insulin causes cells in liver, muscle and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle.

Question 42

Glucagon

Answer 42

Secreted by pancreas. Function to raise blood glucose levels by triggering the release of glycogen stores from the liver (glycogen is the stored form or glucose) Hours after a meal, the body will begin to exhibit lower blood fuller levels. The drop in circulating blood glucose levels triggers the release of glucagon from the pancreas. Stimulating the liver to concert it's glycogen stores back into glucose, then release into the blood steam.

Question 43

Exercise and insulin

Answer 43

Insulin levels drop during exercise (glucose uptake increases) at the same time glucagon secretion increases = helping maintain a steady supply of blood glucose.

Question 44

Catecholamines

Answer 44

* epinephrine (adrenaline) * norepinephrine ^hormones produced by the adrenal glands, on top of each kidney. •Help prepare the body for activity • fight or flight response Hypothalamus triggers adrenal glands to secrete more epinephrine = • increases HR and stroke volume • elevates blood glucose levels • redistributes blood to working tissues • opens up the airways

Question 45

Testosterone

Answer 45

Produced in testes Male produces up to 10x more than females. Responsible for development of male secondary sexual characteristics (facial/body hair, greater muscle mass) Role in growth and repair of tissue in both male and female Raises test. Levels are indicative of an anabolic training status

Question 46

Estrogen

Answer 46

Produced in ovaries of female. With small amounts produced in the adrenals of males. Women of reproductive age have significantly higher levels of estrogen than male = breast and regulation of menstrual cycle Has an influence on fat deposition around the hips, butt and thighs

Question 47

Cortisol

Answer 47

``` Catabolic hormone (associated with tissue breakdown) Under times of stress, (exercise) cortisol is secreted by the adrenal glands and serves to maintain energy supply through the breakdown of carbs fats and proteins during normal exercise & may even help recovery and repair post exercise. High levels of cortisol brought about through over training, excessive stress, poor sleep or nutrition can lead to breakdown of muscle tissue. ```

Question 48

Growth hormone

Answer 48

Release from the pituitary gland in the brain and is regulated by the near by hypothalamus. Stimulated by estrogen, testosterone, deep sleep, vigorous exercise. Increases development of bone, muscle tissue, and protein synthesis. Increases far burning and strengthens immune system. Anabolic hormone that is most responsible for growth and development during childhood till puberty, when primary sex hormones take over.

Question 49

Thyroid hormone

Answer 49

Thyroid gland is at base of neck. (Adam's apple) Release vital hormones responsible for metabolism. Regulated by pituitary gland. Responsible for carb, fat, and protein metabolism, basal metabolic rate, protein synthesis, heart rate, breathing rate, body temp. Low thyroid function = low metabolism, fatigue, depression, weight gain, sensitivity to cold

Question 50

Effects of exercise w/ hormones

Answer 50

Testosterone and growth hormone levels increase after strength training and aerobic exercise. As a result of extremely intense or long bouts of exercise, lower testosterone levels while raising cortisol levels have been found.