Plants and animal responses

Question 1

Skeletal muscle

Answer 1

Make up bulk of body muscle tissue. These are cells responsible for movement, for example biceps and triceps

Question 2

Cardiac muscle

Answer 2

Are found in only the heart, these cells are myogenic,meaning they contract without the need for nervous stimuli

Question 3

Involuntary muscle

Answer 3

Found in stomach and bladder known as smooth muscle

Question 4

Structure of skeletal muscle

Answer 4

Bundles of muscle fibres
Each muscle fibre contains many mibrofibrils long cylindrical organelles made of protein and specialised for contraction. Collectively very powerful

Question 5

What are myofibrils made up of?

Answer 5

Actin- Thinner filament. It consists of two strands twisted around one another
Myosin- Thicker filament. It consists of long rod shaped fibres

Question 6

Myofibrils bands

Answer 6

Light band- appear light as they are region where the actin and myosin don’t overlap
Dark band- appear dark because of presence of thick myosin filament and the overlapping
Z line- found at centre of each light band. The distance between adjacent Z lines is called a sacromere.
H zone- lighter coloured region. Only myosin filaments present at this point

Question 7

Myosin head

Answer 7

Acts a a binding site for actin and ATP

Question 8

Neuromuscular junction

Answer 8

Muscular contraction is triggered when an actin potential arrives at a neuromuscular junction - this is the point where a motor neurone and a skeletal muscle fibres meet

Question 9

Action of adrenaline

Answer 9

Triggers the liver cells to undergo glycogenolysis so that glucose is released into the bloodstream. This allows respiration to increase so more energy is available for muscle contraction.
When adrenaline binds to its receptor, the enzyme adenylyl cyclise is activated
Adenyl Cyclase triggers the conversion of atp into cAMP
The increase in cAMP levels activate specific enzymes called protein kinases which phosphorylate and hence activate, other enzymes