Physiology Recap

Question 1

Where does a sarcomere run from and to?

Answer 1

Z to Z lines

Question 2

What are the thick filaments?

Answer 2

Myosin

Question 3

Describe the myosin filament

Answer 3

2 polypeptides joined together

Question 4

What do the polypeptides in the myosin filament form?

Answer 4

Shaft like tail known as the myosin heavy chain.

AND

A double globular head, known as the myosin light chain.

Question 5

Which chain on the myosin filament contains the ATP binding site ATPase?

Answer 5

Myosin light chain

Question 6

Why are the myosin light chains essential?

Answer 6

They stabilise the myosin head.

Allows phosphorylation to occur.

Question 7

What comes under the thin filaments?

Answer 7

Actin

Troponin

Tropomyosin

Question 8

What are the thin filaments composed of?

Answer 8

2 intertwined strands of F actin.

Question 9

What is each strand of F actin made up of?

Answer 9

G actin subunits (a.k.a globular actin)

Question 10

What does each globular unit have?

Answer 10

AS that can bind to the myosin head = allowing muscle contraction.

Question 11

What exactly prevents the muscle contraction from occurring?

Answer 11

When the G-actin AS on the F-actin chains are covered by tropomyosin molecules.

Question 11

What does each tropomyosin have attached to it?

Answer 11

A calcium ion binding site called TROPONIN

Question 12

What 3 things makes up the troponin complex?

Answer 12

Troponin A

Troponin C

Troponin I

Question 13

Where does Titin run through?

Answer 13

Core of the thick filaments of the myosin

Question 14

Where does the Titian emerge from?

Answer 14

The ends of the filaments

Question 15

Where does Titin bind to?

Answer 15

Z discs

Question 16

What is the purpose of Titin?

Answer 16

To keep thick + thin filaments aligned

Resists overstretching of muscle

Allows recoil of muscle

Question 17

What does nebulin do?

Answer 17

Anchors actin to z discs.

Question 18

Purpose of the z discs

Answer 18

Attach actin to cell membrane.

Question 19

What are z discs usually made up of?

Answer 19

A-actin

Question 20

Purpose of the M line

Answer 20

Attaches myosin to cell membrane

Question 21

What is the M line made up of?

Answer 21

Myomesin

C proteins

Creatine kinase

Question 22

What does the I band contain?

Answer 22

ONLY thin actin myofilaments.

Question 23

What does the A band consists of?

Answer 23

Actin + myosin filaments where they overlap.

Question 24

H zone

Answer 24

Myosin ONLY

Question 25

SLIDING FILAMENT THEORY Step 1 (At rest + the cocking of the myosin head)

Answer 25

At rest = ATP binds to myosin head where ATPase enzyme hydrolyses ATP --> ADP = releasing energy. Energy cocks the myosin head, causing it to point away from the M line and into a higher energy position. (ADP + Pi still remain attached).

Question 26

SLIDING FILAMENT THEORY Step 2 (Myosin head binding)

Answer 26

Cocked myosin head binds to AS on actin mol + the Pi is released (making bond stronger).

Question 27

SLIDING FILAMENT THEORY Step 3 (Release of ADP)

Answer 27

Myosin releases ADP + bends its head. = POWERSTROKE. New ATP binds to myosin head to release it from the actin. ATP hydrolysis by ATPase then cocks the head again + repeat.

Question 28

What are the different ways in which muscle fibre types can be classified?

Answer 28

Histochemical Biochemical Morphological Physologic

Question 29

What makes up a NM junction?

Answer 29

Axon terminals Motor end plate Muscle membrane Schwann cell sheathe

Question 30

What is the motor unit made up of?

Answer 30

AMN Muscle innovated by the AMN

Question 31

What are the different types of motor unit

Answer 31

Slow Fast fatigue Fast twitch fatiguable

Question 32

What happens when a muscle is stretched?

Answer 32

Defamation of the muscle spindle which activates the sensory neurone switch

Question 33

What happens once the sensory neurone switch has been activated by a stretched muscle?

Answer 33

Impulse is sent to spinal cord to synapse w/ motor neurone to cause muscle to contract.

Question 34

What are muscle spindles?

Answer 34

Proprioceptors consisting of modified muscle fibres enclosed in a sheath of connective tissue found w/in the muscle.

Question 35

What happens when a muscle spindle synapses w/ a motor neurone?

Answer 35

It causes muscular contraction as it wants to protect the overstretch.

Question 36

What are Golgi tendon organs?

Answer 36

Tension sensors

Question 37

What do the Golgi tendon organs do when the load increases?

Answer 37

They discharge

Question 38

What happens when there's a discharge in the GTO

Answer 38

It's sensory neurone activates an inhibitory inter-neurone in the spinal cord. == Then inhibits a motor neurone serving that same muscle. Causing it to relax.

Question 39

What is resistance training thought to do in regards to the GTO activity?

Answer 39

Desensitise its activity = allowing for heavier loads to be used.

Question 40

What do sarcomeres in series increase?

Answer 40

Velocity of contraction

Question 41

What do sarcomeres in parallel increase?

Answer 41

Force of contraction

Question 42

What are the 2 main groups for muscle shape?

Answer 42

Parallel Pennate

Question 43

How is total tension calculated?

Answer 43

Passive tension + active tension.

Question 44

In a SHORTENING/CONCENTRIC muscle contraction, what happens to the force as velocity increases?

Answer 44

Force decreases

Question 45

When is the MAXIMUM force occurring in a concentric muscle action?

Answer 45

When there is 0 velocity. = Slower velocity = larger no. of crossbridges formed = Faster velocity = fewer crossbridge attachments

Question 46

At what point on the velocity points is the muscle at isometric strength?

Answer 46

0 velocity

Question 47

What happens to the isometric strength of the muscle when a load greater than isometric strength is applied?

Answer 47

Fibre begins to lengthen. If load is high then the velocity of that lengthening is going to increase.

Question 48

What is the bone made up of?

Answer 48

Inorganic salts Collagen

Question 49

Bone turnover rates

Answer 49

0.5 grams of Calcium every day 5-7% of our bone is recycled every week.

Question 50

Osteoblasts Immature or mature?

Answer 50

Immature

Question 51

What do osteoblasts form?

Answer 51

Osteoid

Question 52

What happens to the osteoid?

Answer 52

Mineralises to form bone.

Question 53

What is the osteoid primarily composed of?

Answer 53

Type 1 collagen

Question 54

What happens to osteoblasts when trapped in bone matrix?

Answer 54

Become osteocytes

Question 55

Osteocytes Mature or immature bone cells?

Answer 55

Mature

Question 56

Function of osteoblasts

Answer 56

Formation of new bone Maintenance of bone matrix Homeostasis of calcium in bone matrix

Question 57

What are osteoclasts responsible for?

Answer 57

Bone reabsorption + remodelling.

Question 58

What is the latent period of a muscular contraction?

Answer 58

Time between the stimulates + initiation of contraction.

Question 59

What follows the latent period?

Answer 59

Contraction period

Question 60

What follows the contraction period?

Answer 60

Relaxation period

Question 61

Define a muscular twitch

Answer 61

Period of contraction + relaxation of a muscle after a single stimulation.

Question 62

Define a muscular twitch

Answer 62

Period of contraction + relaxation of a muscle after a single stimulation.

Question 63

MUSCLES Define summation

Answer 63

When another AP were to stimulate a muscle before a previous muscle twitch had completely relaxed therefore ⬆️ the total amount of tension prod in the muscle.

Question 64

MUSCLES Define tetanus

Answer 64

When the freq of APs generated increases to such a point that muscle tension has reached its peak and then plateaus and no relaxation is observed.

Question 65

Bipennate muscles

Answer 65

2 rows of muscle fibres facing in opposite diagonal directions w. a central tendon i.e like a feather

Question 65

Bipennate muscles

Answer 65

2 rows of muscle fibres facing in opposite diagonal directions w. a central tendon i.e like a feather

Question 66

Flat muscles

Answer 66

Broad Rel thin Sheetlike muscle

Question 67

Unipennate muscles

Answer 67

Muscle fibres/fasicles are all on 1 side of the tendon.

Question 68

Strap muscle

Answer 68

A group of 4 pairs of muscles in the anterior part of the neck.

Question 69

Key function of the Golgi tendon organs

Answer 69

A proprioceptor, sense organ Receives info from tendon that senses tension. When lifting weights - It's the sense organ that tell you how much tension the muscle is exerting.

Question 70

Key function of muscle spindles

Answer 70

Stretch detectors that sense how much + how fast a muscle is lengthened or shortened.