Aging & Muscle

Question 1

What are the 3 types of muscle cells?

Answer 1

1. Skeletal
2. Cardiac
3. Smooth

Question 2

What are the characteristics of skeletal muscle?

Answer 2

Striated 
Attached to the bone
Cylindrical fibres that are parallel
Banded appearance under a microscope
Nuclei in periphery 
Voluntary muscle (conscious control)

Question 3

What are the characteristics of cardiac muscle?

Answer 3

Striated
One nucleus
Branched 
Cardiocytes/cardio monocytes 
Involuntary

Question 4

What are the characteristics of smooth muscle?

Answer 4

Non-striated
Involuntary
Small cells
One nucleus 
Spindle-shaped
Surrounds tissue & walls of hollow organs

Question 5

What is sarcopenia?

Answer 5

A syndrome characterised by progressive and generalised loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life and death

Question 6

Symptoms of sarcopenia

Answer 6

Weakness
Poor balance
Loss of muscle mass
Loss of endurance

Question 7

What is recommended to maintain healthy muscle with ageing?

Answer 7

Increased protein intake to compensate for anabolic resistance and hypermetabolic disease

1 - 1.5g protein / kg BW / day

Exercise & resistance training

Question 8

3 cellular mechanisms of ageing

Answer 8

Telomere length

Oxidative stress

Mitochondrial dysfunction

Question 9

List the 3 types of muscle cells and give 2 characteristics for each type

Answer 9

Skeletal - Striated / Banded appearance / Connected to the bone / Voluntary / Cylindrical fibres that are parellel / Nuclei in periphery

Smooth - Non-striated / Surrounds tissue and walls of hollow organs / Involuntary / Small cells / One Nucleus / Spindel shaped

Cardiac - Involuntary / Branched / One nucleus / Cardiocytes / Striated

Question 10

Compare and contrast smooth muscle cells with cardiac muscle cells (10 marks)

Answer 10

Similarities

• involuntary
• One nucleus
• Innervated by autonomic nerves
• Do not fatigue

Differences

• Cardiac striated, Smooth non-striated
• Cardiac only found in the heart, Smooth lines the walls of internal organs
• Cardiac responsible for pumping blood, Smooth moves internal organs to facilitate the function
• Cardiac branched chains of cells with intercalated discs, Smooth single tapering cells
• Cardiac has an intermediate speed of contraction, Smooth has a low speed of contraction

Question 11

Name 3 body systems and 1 effect smooth muscle cells have within each of these

Answer 11

Integumentary system
- Regulates blood flow to superficial dermis and elevates hair on skin

Cardiovascular system
- Regulates blood pressure and distribution of blood

Urinary system
- Changes filtration rate in kidneys and transports urine into and out of the bladder

Respiratory system
- Changes the diameter of respiratory pathways and changes resistance to airflow

Digestive system
- Moves food along digestive tract and ejects bile from the gallbladder

Question 12

Outline 5 physiological changes associated with ageing

Answer 12

Blood vessels loose elasticity

Cardiac hypertrophy (abnormal enlargement/thickening of heart muscle)

Thickening of valves

Calcification of blood vessels

Reduced strength of respiratory muscles

Pressure in pulmonary artery increases

Intestinal villi shrink, reducing surface area

Loss of neurons

Reduced immune function

Total muscle mass declines

Question 13

3 factors that contribute to sarcopenia

Answer 13

Inadequate nutrition / malabsorption

Age-related - Sex hormones, apoptosis, mitochondrial dysfunction

Disuse - Physical inactivity, immobility

Neurodegenerative disease - motor neuron loss

Cachexia - weakness and wasting of the body due to chronic illness

Question 14

Describe the oxidative stress theory of ageing

Answer 14

Oxidative stress occurs when the production of free radicals exceeds the ability of antioxidants to defend against the free radicals

Question 15

What happens in oxidative stress?

Answer 15

Strands break in DNA

Oxidation of polyunsaturated fatty acids in lipids

Oxidation of amino acids in proteins

Question 16

3 enzymes that defend again free radicals

Answer 16

Superoxide dimutase

Catalase

Glutathione peroxidase

Question 17

3 examples of protein binding metal ions

Answer 17

Iron bound by tranferrin, haemosidierin, ferritin

Copper bound by caeruloplasmin

Metal ions bound by metallothionein

Question 18

4 diet derived antioxidants

Answer 18

α-tocopherol

ascorbic acid

polyphenolics (flavanoids, flavanones, anthocyanins, resveratrol, catechins)

carotenoids (β-carotene, lycopene, zeaxanthin, capsanthin, lutein)

Question 19

4 antioxidants that might be pro-ontioxidants

Answer 19

β-carotene

Iron

Vitamin C

Vitamin E