Muscle Physiology Structure and Function - Lecture 27

Question 1

What is Muscle Health Split into?

Answer 1

Powering Movement & Energy Expenditure

Question 2

What do muscles help us do?

Answer 2

Helps us move and allows our body to function.

Question 3

Calorie burning

Answer 3

Takes place in muscle

Question 4

Functions associated with powering movement

Answer 4

ADLs (Activities of daily living), LTPA (Leisure Time Physical Activity), Occupation, Sport Performance

Question 5

Good muscle health enables good performance of these?

Answer 5

Powering Movement

Question 6

Presence or Absence of Comorbidities associated with?

Answer 6

Metabolic Engine

Question 7

What are some comorbidities that form from muscle inactivity

Answer 7

Obesity, Diabetes, Sarcopenia

Question 8

What happens to our energy expenditure and muscle mass as we become inactive?

Answer 8

Go down; less muscle, less calories burned, less metabolically active tissue

Question 9

Consequences of unhealthy muscle?

Answer 9

Reduced Quality of Life and Independence (ADLs), Reduced Productivity, Limited Career options, increased risk of death/disease.

Question 10

3 Types of Muscle in our body?

Answer 10

Cardiac, Smooth and Skeletal

Question 11

Skeletal Muscle

Answer 11

Majority of the muscle in humans (70%), voluntary, multinucleated, cylindrical and long.

Question 12

What does striation mean?

Answer 12

Pattern of lines or grooves

Question 13

Is skeletal muscle striated?

Answer 13

Yes

Question 14

Cardiac Muscle

Answer 14

Single nucleus per cell, Myogenic (own contraction pattern)

Question 15

In cardiac muscle; apart of the sarcolemma and makes passage ways for cells to communicate, coordinate contraction and cohesive connection between cells

Answer 15

Intercalated disks

Question 16

Is cardiac muscle striated?

Answer 16

More of a lattice like pattern/branched network

Question 17

Sarcomere

Answer 17

Main contractile unit of contraction; in region of myofibril and makes patterns known as striations

Question 18

Smooth Muscle

Answer 18

Single nucleus, fusiform (narrow at end and wide at front), non-striated, involuntary

Question 19

How are the contractions for Smooth Muscle

Answer 19

Weak, slow and sustained because does not generate a lot of force in order to last a long time.

Question 20

Where is smooth muscle usually found?

Answer 20

Internal organs - bladder, colon, stomach, esophagus, uterus, etc.

Question 21

Types of Contraction?

Answer 21

Isometric (Not changing), Eccentric (Increasing), Concentric (Decreasing)

Question 22

Outer most muscle dense sheath?

Answer 22

Epimysium

Question 23

Perimysium (Fascicles)

Answer 23

Groups muscle fibres into bundles; packages the individual fibres.

Question 24

Endomysium

Answer 24

Surrounds the individual muscle fibres

Question 25

Single muscle fibre (muscle cell) is found within?

Answer 25

Endomisyium

Question 26

Myofibrils

Answer 26

Contractile muscle containing filaments; contraction takes place, and give striated appearance

Question 27

Does a muscle fibre have multiple myofibrils

Answer 27

Yes; a muscle cell will have multiple myofibrils with the purpose of having filaments for muscle contraction

Question 28

Purpose of Motor Neurons and Blood Vessels in muscle fibres

Answer 28

They are intricately woven because muscles need blood flow and signals to contract and stay alive. They deliver and take things out of muscles

Question 29

Muscle Fibre Nucleus/Nuclei

Answer 29

Governs cell behaviour, contains DNA

Question 30

Sarcolemma

Answer 30

Muscle cell membrane; wraps around muscle fibre

Question 31

Sarcoplasm

Answer 31

Cytoplasm, holds organelles

Question 32

Sarcoplasmic Reticulum

Answer 32

Key for Calcium storage which is used for muscle contraction.

Question 33

Contains filaments where muscle contraction takes place

Answer 33

Myofibrils

Question 34

T-Tubule

Answer 34

Extensions of sarcolemma; allows signals from nervous system to penetrate into muscle fibre

Question 35

Filaments in Sarcomere

Answer 35

Actin (Thin) and Myosin (Thick)

Question 36

Actin and Myosin

Answer 36

Contractile proteins; Filaments arranged within sarcomere are what make striations in muscles

Question 37

How do Actin and Myosin work

Answer 37

Actin and Myosin overlap and when muscles contract they overlap more, and when they relax they overlap less.

Question 38

Z-line/disc

Answer 38

Divides sarcomeres as there are many in myofibril while acting as an anchor for actin filament.

Question 39

Within the sarcomere; expands and shrinks with muscle contraction and has an M line running down the middle

Answer 39

H-zone

Question 40

How many bands are there

Answer 40

A band and I band

Question 41

A band?

Answer 41

Dark band which is Myosin (little actin)

Question 42

I band

Answer 42

Light band (Actin)

Question 43

Synapse

Answer 43

Connection between (synaptic cleft) end of one nerve to a muscle fibre

Question 44

Action potential

Answer 44

Threshold of electric depolarization that causes signal to move down the line

Question 45

How is action potential (signals) driven?

Answer 45

Driven by ions in the body

Question 46

All or none response

Answer 46

The signal once it reaches the threshold must give an all out response or nothing at all.

Question 47

Neuromuscular Junction

Answer 47

Where nerve meets with muscle

Question 48

Axon

Answer 48

Passes signal down it and it's covered by myelin sheath

Question 49

Acetylcholine

Answer 49

Inside the axon terminal in the neuromuscular junction and released into space between nerve and muscle called synaptic cleft.

Question 50

What happens after signal reaches the neuromuscular junction and releases acetylcholine

Answer 50

Signal travels down T-Tubules into muscle fibre cells and causes release of calcium.

Question 51

What releases calcium?

Answer 51

Sarcoplasmic reticulum

Question 52

Where does the process of signal reaching from nerve to muscle take place?

Answer 52

Neuromuscular Junction

Question 53

What's in Actin?

Answer 53

Tropomyosin and Troponin

Question 54

Tropomyosin

Answer 54

Thin protein wrapped around actin that blocks binding sites for myosin while relaxed

Question 55

Binding site for calcium; moves tropomyosin when calcium binds

Answer 55

Troponin

Question 56

The Role of Calcium

Answer 56

When the signal reaches the sarcoplasmic reticulum, calcium releases and binds to troponin and exposes myosin binding site.

Question 57

Sliding Filament Theory?

Answer 57

A formation of cross bridges with actin and myosin that involves ATP and calcium.

Question 58

Step 1 of SFT?

Answer 58

Myosin heads energize by going from bent to stretched. ATP is hydrolyzed by heads into ADP and P

Question 59

Step 2 of SFT?

Answer 59

Phosphate disappears and crossbridge is formed between Actin and Myosin

Question 60

Power stroke; myosin head rotate to middle of sarcomere and pull actin along with it. ADP gets released

Answer 60

Step 3 of SFT

Question 61

Detachment via ATP binding to Myosin

Answer 61

Step 4 of SFT

Question 62

How does contraction happen continuously if ATP appears and blocks the connection?

Answer 62

As long as signal keeps going more calcium is released and ATP is available contractions can continue to happen