29.3 - 29.6

Question 1

A motor unit is a ___ ___ and all of the ___ ___ innervated by it.

Answer 1

Motor neuron

All muscle fibres innervated by it

Question 2

A motor unit is a ___ ___ and all of the ___ ___ innervated by it.

Answer 2

Motor neuron

All muscle fibres innervated by it

Question 3

What are the 3 types of motor units/fibres?

Answer 3

Fast and rapidly fatigable e.g. sprint
Intermediate - fast and resistant to fatigue
Slow and resistant to fatigue e.g. endurance

Question 4

There are different types of muscle fibres in people. In some fibres there is only one type of myosin i.e. ‘___’, and in others there is more than one type of myosin i.e. ‘___’.

Answer 4

Pure

Hybrid

Question 5

Sarcopenia is an ___-associated loss of ___ muscle mass and function. It affects all people independent of lifestyle, disease states, ethnicity, etc. There is infiltration of non-contractile tissue like ___ tissue and ___, and muscle stiffening.

Answer 5

Age-associated loss of skeletal muscle mass and function
(Not to be confused with cachexia - wasting and weakness due to severe chronic illness)
Infiltration of connective tissue and fat

Question 6

Diagnosis of sarcopenia is consistent with a gait speed of

Question 7

There is loss of muscle strength with age. ___ muscles (e.g. EDL) are affected more than ___ muscles (e.g. soleus). There is age-related loss of motor ___ AND muscle ___.

Answer 7

Fast muscles are affected more than slow muscles - slow muscles are protected
Age-related loss of motor units AND muscle fibres

Question 8

There is an overall slowing of muscle due to denervation or reinnervation of type ___ (fast) motor units. In ___, muscle fibres die. In ___, slow nerves innervate and replace fast fibres with slow fibres. Therefore, there is an increase in type ___ (slow) muscle fibres.

Answer 8

Type 2 (fast) motor units
Denervation -> death of muscle
Reinnervation -> change from fast nerve to slow nerve -> slowing of muscle
Type 1 (slow) muscle fibres/motor units

Question 9

In sarcopenia/ageing, there is progressive atrophy of type ___ (___ ___) fibres.

Answer 9

Type 2 (fast twitch)

Question 10

With ageing there is a decrease in circulating levels of ___ hormones like GH, IGF-1 and testosterone. Supplementing these hormones alone is not effective at reducing sarcopenia. The best outcome is achieved by using supplements in conjunction with ___ ___.

Answer 10

Anabolic hormones

Strength training

Question 11

Duchenne muscular dystrophy is due to a mutation in the ___ gene on ___.

Answer 11

Dystrophin gene

Xp21

Question 12

The ___ mouse is a model of DMD as it lacks expression of ___, but it upregulates ___ leading to a normal lifespan.

Answer 12

Mdx mouse
Lacks expression of dystrophin
Upregulates utrophin

Question 13

There are different types of muscle fibres in people. In some fibres there is only one type of myosin i.e. ‘___’, and in others there is more than one type of myosin i.e. ‘___’.

Answer 13

Pure

Hybrid

Question 14

Sarcopenia is an ___-associated loss of ___ muscle mass and function. It affects all people independent of lifestyle, disease states, ethnicity, etc. There is infiltration of non-contractile tissue like ___ tissue and ___, and muscle stiffening.

Answer 14

Age-associated loss of skeletal muscle mass and function
(Not to be confused with cachexia - wasting and weakness due to severe chronic illness)
Infiltration of connective tissue and fat

Question 15

The gold standard treatment for Duchenne muscular dystrophy is ___. There are many other treatments.

Answer 15

Corticosteroids

Question 16

There is loss of muscle strength with age. ___ muscles (e.g. EDL) are affected more than ___ muscles (e.g. soleus). There is age-related loss of motor ___ AND muscle ___.

Answer 16

Fast muscles are affected more than slow muscles - slow muscles are protected
Age-related loss of motor units AND muscle fibres

Question 17

There is an overall slowing of muscle due to denervation or reinnervation of type ___ (fast) motor units. In ___, muscle fibres die. In ___, slow nerves innervate and replace fast fibres with slow fibres. Therefore, there is an increase in type ___ (slow) muscle fibres.

Answer 17

Type 2 (fast) motor units
Denervation -> death of muscle
Reinnervation -> change from fast nerve to slow nerve -> slowing of muscle
Type 1 (slow) muscle fibres/motor units

Question 18

In sarcopenia/ageing, there is progressive atrophy of type ___ (___ ___) fibres.

Answer 18

Type 2 (fast twitch)

Question 19

The ___ nephron reabsorbs calcium by a series of transporters e.g. ECaC, Na+-Ca2+ antiport, Ca2+ ATPase.

Answer 19

Distal

Question 20

With ageing there is a decrease in circulating levels of ___ hormones like GH, IGF-1 and testosterone. Supplementing these hormones alone is not effective at reducing sarcopenia. The best outcome is achieved by using supplements in conjunction with ___ ___.

Answer 20

Anabolic hormones

Strength training

Question 21

PTH hyposecretion (e.g. hypoparathyroidism) is usually due to ___ attack of the gland and results in ___calcaemia and ___phosphataemia.

Answer 21

Autoimmune attack
Hypocalcaemia
Hyperphosphataemia

Question 22

The ___ mouse is a model of DMD as it lacks expression of ___, but it upregulates ___ leading to a normal lifespan.

Answer 22

Mdx mouse
Lacks expression of dystrophin
Upregulates utrophin

Question 23

What is the sequence of tissue phases after skeletal muscle injury? What phase is important for recruitment of stem cells?

Answer 23

Degeneration > inflammation > regeneration > fibrosis

Inflammation is important for recruitment of stem cells

Question 24

In normal muscle repair, inflammation allows activation of ___ cells i.e. muscle stem cells. But in DMD, the inflammatory signature is different resulting in ___ - the replacement of contractile muscle fibres with extracellular connective tissue.

Answer 24

Satellite cells i.e. muscle stem cells

Fibrosis

Question 25

The gold standard treatment for Duchenne muscular dystrophy is ___. There are many other treatments.

Answer 25

Corticosteroids

Question 26

___ hormone is permissive for growth.

Answer 26

Thyroid

Question 27

Only ___/___ of calcium from the diet is absorbed.

Answer 27

1/3

Question 28

Most calcium is lost via ___, but some is lost via ___.

Answer 28

Most via urine

Some via faeces

Question 29

The ___ nephron reabsorbs calcium by a series of transporters e.g. ECaC, Na+-Ca2+ antiport, Ca2+ ATPase.

Answer 29

Distal

Question 30

PTH hypersecretion (e.g. hyperparathyroidism) is usually due to a ___ and results in ___calcaemia and ___phosphataemia.

Answer 30

Tumour
Hypercalcaemia
Hypophosphataemia

Question 31

PTH hyposecretion (e.g. hypoparathyroidism) is usually due to ___ attack of the gland and results in ___calcaemia and ___phosphataemia.

Answer 31

Autoimmune attack
Hypocalcaemia
Hyperphosphataemia

Question 32

More than 1/2 of total deaths around the world are in ages ___ years and older.

Answer 32

60

Therefore, 1/2 in

Question 33

Almost 1/5 of all deaths are of children aged under ___ years.

Answer 33

5

Question 34

In Africa, death affects the ___, but in high income countries, death affects the ___.

Answer 34

Young

Old

Question 35

Group I conditions refer to ___, maternal, perinatal and nutritional conditions. Group II conditions refer to ___ diseases. Group III conditions refer to ___. Group ___ conditions are esp. prevalent in poor populations in an early phase of the ___ transition. The largest difference between sexes is in group ___ conditions.

Answer 35

Group I Communicable
Group II Noncommunicable
Group III Injuries
Group I
Epidemiological
Group III

Question 36

___ diseases are the leading cause of death. ___ heart disease and ___ disease are leading causes of death in high income AND low/middle income countries. After these causes, there are differences between high income and low/middle income countries.

Answer 36

Cardiovascular
Ischaemic heart disease (1st)
Cerebrovascular disease (2nd)

Question 37

There is a higher death rate in ___ (gender) due to cardiovascular diseases. Why? There is a higher death rate in ___ (gender) due to unintentional AND intentional injuries.

Answer 37

Females
Due to loss of protection after menopause
Males

Question 38

In ___ income countries, infectious and parasitic infections and perinatal conditions dominate after cardiovascular disease.

Answer 38

Low

Question 39

What are the common cancers causing death in males, and in females?

Answer 39

Males: lung -> stomach -> liver -> colorectal -> esophageal -> prostate
Females: breast -> lung -> stomach -> liver -> cervical

Question 40

Poor ___ is an underlying cause of approx. 30% of deaths in children under 5 y.o. This is higher if there is sub-optimal breast feeding. Most causes of death in children under 5 y.o. are preventable or treatable.

Answer 40

Nutrition

Question 41

The target of Millennium Development Goal ___ is to reduce by 2/3s between 1990 and 2015 the under 5 y.o. mortality rate.

Answer 41

4

Question 42

___ is the main cause of adult mortality in Africa.

Answer 42

AIDS

Question 43

Projections for disease and mortality are expected to change due to the ___ population and its effects on the ___ transition.

Answer 43

Ageing population

Epidemiological transition

Question 44

There is a high incidence of cancers in the world, esp. in ___ income countries. BUT ___ cancer is more prevalent in low/middle income countries due to ___.

Answer 44

High incidence of cancers in high income countries

Cervical cancer is more prevalent in low/middle income countries due to HPV

Question 45

African countries are most affected by disease MORBIDITY in terms of ___, esp by group ___ conditions.

Answer 45

DALYs - disability adjusted life years

Group I conditions - communicable, maternal, perinatal and nutritional conditions

Question 46

What are the main known risk factors for disease and death?

Answer 46

High blood pressure
Childhood underweight
Environmental risks e.g. unsafe water, poor sanitation and hygiene, indoor smoke
Low fruit and vegetable intake, lack of exercise, diabetes
Overweight/obesity
Alcohol/tobacco
Unsafe sex

Question 47

Malnutrition (esp. overnutrition) is a predictor of ___ in later life.

Answer 47

Obesity