lecture 14

Question 1

what are the major functions of muscle tissue

Answer 1

movement
maintaining posture
generate heat
stabilize joints

Question 2

explain the major functions of muscle tissue

Answer 2

o Movement – locomotion, fine movements but also some responsible for movement in the body.
o Maintain posture – helps us to fight the forces of gravity, and be able to sit up
o Generate heat – helps to regulate body temperature. When cold the body shivers which is the muscles way of contracting quickly to warm up the body, and produce heat in a fast twitch method
o Stabilize joints – synovial joints are stabilized by this, stabilizes the body

Question 3

skeletal muscle

Answer 3

• Attaches directly to the skeleton, and we voluntarily control it. Has very visible or prominent striations, is multinucleated. Are long, cylindrical shaped cells. Can produce very powerful contractions but can tire very easily.
  
  • Telling our body to walk, or stand up, or write.

Question 4

cardiac muscle

Answer 4

 The only muscles that have intercalated disks, which allows for communication. Is involuntary, has striations (not as defined as skeletal), has a branching structure. Is only found in the lining of the walls in the heart and has one or two nuclei per cell.

Question 5

smooth muscle

Answer 5

 Has no striations, one nucleus per cell, and is spindle shaped that tapers at the end of each one. It lines the hollow visceral organs. During contraction it helps propel things across the body and is involuntary.
* Primary function is to remove fluids

Question 6

muscle layer

Answer 6

 Muscle layer (the organ layer), is looking at the muscle as a whole and can be seen with the naked eye
* Epimysium – is an “overcoat” of dense irregular connective tissue that surrounds the whole muscle. Surrounds the individual ones, and is between each fascicle.

Question 7

epimysium

Answer 7

Epimysium – is an “overcoat” of dense irregular connective tissue that surrounds the whole muscle. Surrounds the individual ones, and is between each fascicle.

Question 8

fascicle

Answer 8

 Fascicle – is the unit or portion of the muscle, is bundled up by discrete units that are all surrounded by their own unit, which is called the perimysium. Is a bundle of muscle fibers.
* Perimysium – perimysium and fascicles -> are within each muscle, are fibers that are grouped into fascicles, which are surrounded by dense irregular connective tissue called the perimysium

Question 9

perimysium

Answer 9

Perimysium – perimysium and fascicles -> are within each muscle, are fibers that are grouped into fascicles, which are surrounded by dense irregular connective tissue called the perimysium

Question 10

muscle fiber

Answer 10

– (is a single cell) long cylindrical extensions that can be up to 30cm long
* Endomysium – a wispy sheath of areolar connective tissue that surrounds each individual muscle fiber. Prevents friction between the individual cells that are together.

Question 11

endomysium

Answer 11

Endomysium – a wispy sheath of areolar connective tissue that surrounds each individual muscle fiber. Prevents friction between the individual cells that are together

Question 12

myofibril

Answer 12

• The contractile organelle of the muscle. Makes up to around 80% of it. The myofibrils run together in a row, and the striations of the muscle are caused by it.

Question 13

sarcomere

Answer 13

The contractile unit of the cell; is a distinct segment of a myofibril. It lines up end to end in the myofibril

Question 14

myofilament

Answer 14

• The functional components that make up the sarcomere. Creates it and helps to allow for muscle contraction to occur.

Question 15

direct muscle attachment

Answer 15

 Direct – when the muscles are directly fused with the bone
* The intercostal muscles attaching the ribs to each other

Question 16

indirect muscle attachment

Answer 16

 Indirect – is more common
* Tendon – a rope-like structure of dense irregular connective tissue that connects muscle to bone.
o Biceps brachii, and brachioradialis
* Aponeurosis – a flat sheet of connective tissue, it provides attachment
o The abs/obliques

Question 17

sarcolemma

Answer 17

the plasma membrane of a muscle cell

Question 18

sarcoplasm

Answer 18

 Is between the organelles. Considered the cytoplasm of the muscle cell, has lots of stored glucose.

Question 19

SR = sarcoplasmic reticulum

Answer 19

 Is the specialized smooth endoplasmic reticulum of muscle cells. Helps to regulate calcium. The calcium is inside, so that when calcium needs to be released it can be.

Question 20

t-tubules

Answer 20

 Are made up of extensions of the sarcolemma that penetrate into the cells, are simply membrane extensions.

Question 21

m line

Answer 21

the middle of the sarcomere

Question 22

h zone

Answer 22

the zone in the middle that contains myosin and no actin. tends to shrink for contraction

Question 23

a band

Answer 23

the area where thick filaments are and the length does not change

Question 24

i band

Answer 24

an area on the end where there is actin by no myosin. Will shrink with contraction

Question 25

z disc

Answer 25

is on the end

Question 26

thin filaments

Answer 26

 Contains actin, is anchored to the Z disc
* Each actin monomer has an active site where myosin can bind during contraction

Question 27

thick filaments

Answer 27

 Contains myosin motor proteins, is anchored to the M line
* Myosin motor proteins -> are rod-like tails with two globular heads (double headed golf club) each myosin head has a binding site for actin and for ATP

Question 28

when two filaments overlap what happens

Answer 28

it allows for muscle contraction

Question 29

myosin

Answer 29

thick filament

Question 30

actin

Answer 30

thin filament

Question 31

tropomyosin

Answer 31

 Is a strand of protein that spirals around actin. When muscles are relaxed it blocks the binding site to prevent contraction.

Question 32

troponin

Answer 32

 Is the protein that moves tropomyosin out of the way so that the binding can happen. Must change shape.

Question 33

titin

Answer 33

 Holds the thick filaments in place and the structure together (big protein)

Question 34

dystrophin

Answer 34

 Structural proteins to hold the thin filaments to the extracellular matrix

Question 35

describe what happens to the different components of the sarcomere during muscle contraction and relaxation (sliding filament theory)

Answer 35

 The sliding filament theory is when there is an overlap in the components because myosin binds to actin, and the head then pivots and pulls over and over.
* Essentially like hands pulling hand over hand continuously on a rope.