Muscles

Question 1

Types of muscle

Answer 1

Involuntary smooth muscle
Cardiac muscle
Voluntary skeletal or striated muscle

Question 2

Structure of involuntary smooth muscle

Answer 2

Individual cells tapered at both ends

Spindle like shape

Question 3

Structure of cardiac muscle

Answer 3

Individual cells form long fibres joined by intercalated discs
Branch to form cross bridges between fibres

Question 4

Structure of voluntary skeletal or striated muscle

Answer 4

Arranged in antagonistic pairs
Cells form fibres surrounded by a membrane (sarcolema)
Sarcoplasm

Question 5

Stimulating contraction

Answer 5

Acetylcholine binds to receptors on sarcolemma
Na+ channels open, causing depolarisation of sarcolemma
Wave of depolarisation travels down transverse tubules
Reaches sarcoplasm in reticulum which releases Ca2+ ions into sarcoplasm

Question 6

Contraction of muscles

Answer 6

Ca2+ bind to troponin
Troponin pulls on tropomyosin, exposing myosin binding sites on actin
Myosin head binds forming cross bridges
Performs power stroke releasing ADP and Pi
ATP can release myosin head

Question 7

H-zone

Answer 7

Between the two actin chains

The exposed myosin

Question 8

A-band

Answer 8

Whole myosin chain

Question 9

I-band

Answer 9

From one end of myosin to the other

Only actin

Question 10

Z-line

Answer 10

Middle of actin strand

Question 11

Sacromere

Answer 11

From one Z-line to the other

Question 12

Methods of supply ATP

Answer 12

Aerobic respiration in mitochondria
Anaerobic respiration in sarcoplasm
Creatine phosphate
-Extra phosphate to bind to ADP to make ATP