B16 - Homeostasis

Question 1

What are antagonistic pairs?

Answer 1

Pairs of muscles involved in contraction and relaxation.

Question 2

What is an antagonist?

Answer 2

The muscle that is relaxing

Question 3

Give an example of an antagonist.

Answer 3

Tricep: is relaxed when the arm is bent

Question 4

What is an agonist?

Answer 4

The muscle that is contracted

Question 5

Give an example of an agonist.

Answer 5

Bicep: when the arm is bent

Question 6

Describe the sarcolemma.

Answer 6

Membrane of muscle fibres. Inward folds are known as T-Tubules

Question 7

What are T-Tubules (Transverse Tubules)?

Answer 7

Important in initiating muscle contraction

Question 8

Function of the sarcoplasmic reticulum?

Answer 8

Store for Ca2+ ions

Question 9

Why do muscle fibres require lots of mitochondria?

Answer 9

Provide ATP to power contraction

Question 10

What are myofibrils?

Answer 10

Cylindrical organelles that run the length of muscle fibres. They are the site of muscle contraction.

Question 11

What are thick filaments made from?

Answer 11

Myosin protein

Question 12

What are thin filaments made from?

Answer 12

Actin protein

Question 13

What is the A-Band?

Answer 13

The overlapping region of thin and thick filaments

Question 14

What is the H-band?

Answer 14

Only myosin (thick filaments)

Question 15

What is the I-Band?

Answer 15

Only actin (thin filaments)

Question 16

What is the Z-Line?

Answer 16

Marks the end of the sarcomere

Question 17

Overview of the sliding filament theory.

Answer 17

• Depolarisation of the sarcolemma (arrival of an action potential)
• Contraction of sarcomeres (actin and mysosin slide over one another)
• Muscle contraction
• Muscle Relaxation

Question 18

What type of heads to myosin filaments contain?

Answer 18

Globular heads.

Question 19

How many binding sites do globular heads have?

Answer 19

Two

Question 20

What do the binding sites on the globular heads do?

Answer 20

One binds to ATP and the other to actin

Question 21

What is the binding site on the actin filament known as?

Answer 21

Actin-myosin binding site.

Question 22

What is tropomyosin?

Answer 22

• Blocks actin-myosin binding site when at rest
• Located on the actin filaments

Question 23

What are some ways ATP is produced to power contraction?

Answer 23

• Aerobic and Anaerobic Respiration
• Phosphocreatine

Question 24

How does phosphocreatine result in more ATP?

Answer 24

Donates an inorganic phosphate to ADP, which results in ATP production

Question 25

Where are calcium ions released from?

Answer 25

Sarcoplasmic Reticulum (SR)

Question 26

How do calcium ions affect tropomyosin?

Answer 26

Ca2+ bind to the protein attached to tropomyosin, changing the shape of the protein - Causes tropomyosin to move, no longer blocking the actin-myosin binding site

Question 27

Role of ATP hydrolase?

Answer 27

ATP = ADP +Pi which powers muscle contraction

Question 28

Why do myosin heads end up bending?

Answer 28

Energy is released from when ATP is hydrolysed. Movement of the head causes filaments to slide past one another.

Question 29

What does the shortening of the sarcomere lead to?

Answer 29

Muscle contraction

Question 30

What are the steps in halting contraction?

Answer 30

-Removal of calcium ions - Movement of tropomyosin - Lengthening of the sarcomere

Question 31

Give examples of slow-twitch muscles

Answer 31

Back and neck

Question 32

What are slow-twitch muscles used for?

Answer 32

Endurance and slow movement over long time periods

Question 33

What energy do slow-twitch fibres rely on?

Answer 33

Energy from aerobic respiration

Question 34

Give some features of slow-twitch muscles.

Answer 34

- Lots of mitochondria - Lots of capillaries to supply oxygen - Low levels of glycogen and phosphocreatine

Question 35

Give examples of fast twitch muscles

Answer 35

Arms and legs

Question 36

What are fast twitch muscle fibres used for?

Answer 36

Fast and strong movements over short periods

Question 37

Describe the appearance of fast-twitch muscle fibres

Answer 37

Short and wide

Question 38

Describe the appearance of slow twitch muscle fibres

Answer 38

Long and thin

Question 39

Where do fast twitch muscles get their energy from?

Answer 39

Anaerobic respiration

Question 40

What is negative feedback?

Answer 40

Restores the system to its original level

Question 41

Describe what happens during negative feedback.

Answer 41

Change is detected by receptors Change is counteracted by effectors

Question 42

Why is blood concentration important?

Answer 42

- Meeting respiratory demands - Maintaining water potential

Question 43

What is glycogenolysis?

Answer 43

Glycogen into glucose

Question 44

What is glycogenesis?

Answer 44

Glucose into glycogen

Question 45

What is gluconeogenesis?

Answer 45

Glycerol and amino acids into glucose

Question 46

Does insulin revolve around a high or low blood glucose concentration?

Answer 46

High

Question 47

What cells detect a high blood glucose concentration?

Answer 47

B cells in the islets of Langerhans which secrete insulin into the blood

Question 48

What effect does insulin have on muscle cells?

Answer 48

Binds the receptors, resulting in more glucose channel proteins

Question 49

What process in the liver does insulin stimulate?

Answer 49

Glycogenesis - glucose converted into glycogen (high conc. so we want to remove glucose)

Question 50

State the significance of insulin.

Answer 50

Maintains optimum blood water potential otherwise water potential would decrease - cells shrivel and die.

Question 51

Which type of cells detect glucagon?

Answer 51

Alpha cells in the islets of Langerhans which secrete glucagon into the body.

Question 52

Which processes does glucagon stimulate in the liver?

Answer 52

- Glycogenolysis - Gluconeogenesis We need more glucose, so it has to be created

Question 53

Importance of glucagon?

Answer 53

- Slows the rate of respiration - Provides energy for respiration by producing glucose

Question 54

Effect on adrenaline in the liver?

Answer 54

- Activates glycogenolysis - Inhibits glycogenesis