Muscles

Question 1

What are the 3 types of muscle?

Answer 1

-Cardiac
-Smooth (involuntary)
-Skeletal (voluntary)

Question 2

What word describes cardiac muscle?

Answer 2

Myogenic

Question 3

Where is smooth muscle found?

Answer 3

Gut, blood vessels, rhythmical

Question 4

What is skeletal muscle?

Answer 4

Attached by tendons to bones

Question 5

Describe how muscles work in antagonistic pairs

Answer 5

-Skeletal muscles work together to move bones
-One muscles will contract whilst the other relaxes
-The contracting muscle is the agonist and the relaxing is the antagonist.
-Tendons attach muscles to bones
-Ligaments attach bones to other bones

Question 6

Briefly describe muscle fibres

Answer 6

-Skeletal muscles are made of muscle fibres which are long bundles of long cells.
-Cell membrane is called the sarcolemma, where sections fold inwards and stick to the sarcoplasm (cytoplasm)
-The folds are called transverse tubules or T-tubules and help spread impulses throughout the sarcoplasm.
-Contain lots of mitochondria to provide ATP.

Question 7

What are fast twitch fibres?

Answer 7

white muscle

-Adapted to sudden bursts of energy
-Consume ATP quickly, O2 consumption is not enough, therefore energy is gained from anaerobic respiration
-The enzymes of the glycolosis pathway are plentiful and have few mitochondria.
-High store of phosphocreatine
-Thicker and more numerous myosin fibres

Question 8

What are slow twitch muscles fibres?

Answer 8

red muscle

-Sustained low levels of activity
-Oxygen demand keeps up with pace with ATP supply
-Glucose broken down in glycolosis, krebs and oxidative phosphorylation.
-Many mitochondria
-Good blood supply
-Contain lots of myoglobin to act as an oxygen store

Question 9

Put single muscle fibres, whole muscle, myofibril, and bundle of muscle fibres in order from largest to smallest.

Answer 9

Whole muscle

Bundle of muscle fibres

Single muscle fibres

Myofibril

Question 10

How does an action potential trigger muscle contractions?

Answer 10

1. Like synaptic transmission: Ca+ channels open, stimulates vesicles to fuse, release acetylcholine.
2. Acetylcholine binds to receptors on muscle membrane, opening Na+ channels, Na+ floods in.
3. Postsynaptic membrane depolarises, an action potential if threshold is met. This travels along the muscle cell membrane and into the special structures called T-tubules.
4. The T-tubules channel the action potential into the cell towards the sarcoplasmic reticulum. this organelle releases stored Ca2+ ions into the cell cytoplasm in response to the depolarisation.
5. Increase in conc of Ca2+ in muscle cell cytoplasm that causes the cell to contract. the acetylcholine is recycled by enzyme action and returned to the neuron.