Cellular Ageing

Question 1

what are the characteristics of ageing and senescence

Answer 1

slow occrung process
compromises entire musculature leadings to frailty
unavoidable.

Question 2

changes to HAIR

Answer 2

– Gradual thinning & graying of the hair results from a cessation of pigment production of both men & women
– Hair loss is cause by destruction of the germ centers that produce hair follicles
– Men usually do not lose facial hair as they age
– Women develop patches of hair on their face especially on their chin

Question 3

changes to physical appearance

Answer 3

• In women, especially near menopause age as the ovary functions slow down then there can be more DHEA or androgens produced thus causing an increase in facial hair or hirsutism. As the woman begins to produce more androgens rather than estrogens she may begin to experience an increase in facial hair.

Question 4

changes to skin

Answer 4

4 steps to make a wrinkle
• the outer layer of skin becomes thinner through cell loss
• the collagen fibers that make up the connective tissue lose much of their flexibility, making the skin less able to regain its shape after a pinch
• elastin fibers in the middle layer of skin lose their ability to keep the skin stretched out
• the underlying layer of fat, which helps provide padding to smooth out the contours, diminishes.

Question 5

changes to body build

Answer 5

• A decrease in height
• Fluctuations in weight and shifts in body composition
• Muscle atrophy
• Compression of spinal vertebrae / can spinal deform and osteopeorosis of the spine

Question 6

changes in the skeletal system

Answer 6

– The loss of bone
– Osteoporosis –defined as a decrease in bone mass & strength
– Osteoarthritis – a degenerative joint disease
• Osteoperosis is particular bad in women because of e2 where as men are protected to a degree from testosterone.

Question 7

changes in the cardiovascular system

Answer 7

– The main function of heart is pumping blood
– Age-related structural changes in the heart
• the accumulation of fat deposits
• the stiffening of the heart muscle due to tissue changes
• Typically the left ventricle is less effective at pumping and accumulation of fat within the cardiomyoctyes – contributing to impaired ability to act As a pump

Question 8

examples of cardiovascular disease

Answer 8

• Ischemic heart disease
• Cardiac Arrhythmias
• Angina -narorowing of vessles pain in heart and dwon the arms
• Myocardial infarction
• Atherosclerosis -plaque deposits impair blood flow and create further hypertension particually in arterioles
• Cerebrovascular Disease
• Hypertension

Question 9

changes in the respiratory system

Answer 9

– Age-related to structural and functional
– With increasing age, the rib cage and the air passageways become stiffer
– Changes in the maximum amount of air we can take into the lungs in a single breath
– Respiratory disease
• Emphysema

Question 10

changes In the reproductive system

Answer 10

– Women
• The major reproductive change in women during adulthood is the loss of the ability to bear children
• Begins in the 40s, as menstrual cycles become irregular and by the age of 50 to 55 it is usually complete - menopause
• A variety of physical and psychological symptoms
– Men
• Men do not have a physiological & cultural event to mark reproductive changes
• Do experience a normative decline in the quantity of sperm

Question 11

changes in vision

Answer 11

• The major changes in visual functioning can be group into 2 classes :
I. changes in the structures of the eye
» disease: cataracts & glaucoma
II. changes in the retina
» usually begin 50s
» disease: macular degeneration & diabetic retinopathy (glucose impairs the small vessels behind the eye)

• Age related decrease in the ability to focus on nearby objects -presbyopia
• Age related decrease the ability to see detail and to discriminate different visual patterns -acuity

Question 12

changes in hearing

Answer 12

greatest loss with high pitched tones / presbycusis

tinnitus can occur

inability to hear over background sound which is always present in the outside world

Question 13

changes in taste

Answer 13

taste changes lead to a natural decline in appetite and therefore calorie intake

Question 14

changes in smell

Answer 14

ability to detect doors remains in 60’s, until it then rapidly declines.

Question 15

changes in the digestive system

Answer 15

eg intestine / gallbladder / liver

overall affecting macro intake for MPS and metabolic functioning leading to lack of substrates for new tissues (eg leaking protein into fences from inadequate absorption

Question 16

how does telomere shortening cause cell senescence

Answer 16

somatic cells usually lack telomerase activity, meaning there telomeres shorten with each cell division

cells may go into crisis after reaching zero telomere length

reactivation of telomerase however ables cells to survive crisis and to become immortal

Question 17

explain oxidative damage theory

Answer 17

95% off cells energy is produced in the mitochondria and therefore most oxygen is utilised there. however oxygen is damaging in high concentrations - being toxic to most animals and plants.

protein turnover requires ATP to bond AA covalently and therefore oxidative damage is hungering muscle mass down the line by interfering with MPS and MPB

Question 18

What is the evidence for oxidative damage theory

Answer 18

house fly experiment example

or

correlations between species-specific levels of antioxidant defences and lifetime energy expenditure.

Question 19

how would you test oxidative damage theory

Answer 19

1. Construct long-lived and short-lived animals and then assay their antioxidant defense levels.
2. Construct animals with genetically altered levels of antioxidant defense enzymes and then test for lifespan.

Question 20

what is mitochondrial free radical theory

Answer 20

damage to mitochondrial genome, impairing mitochondria gene expression.
leading to inability of mitochondria to replicate and divide further leading to a reduction in energy production

with damaged mitochondria replicating taste retain than intact mitochondria.
- good to look at as, DNA is well preserved in mitochondria - genes are so few and and so not subject to great variation.

Question 21

what Is altered protein theory.

Answer 21

changes to protein impairing cellular process in a progressive manner until submittal levels reached.

Question 22

what can reduce protein function

Answer 22

post translational changes such as

• covalent modifications
• protein carbonyl levels raising
• protein modifications such as glycation

Question 23

what is HAYFLICKS LIMIT

Answer 23

cells are only capable of a limited number of population doublings in culture

Question 24

when is cellular senescence triggered

Answer 24

when cells acquire one or a few critically short telomeres

Question 25

how does telomerase work

Answer 25

addition of TTAGGG repeats (hexameric) onto the telomeric ends of chromosomes, thus compensating for the erosion of telomeres that occurs in its absence

Question 26

can telomerase give rise to more cancers

Answer 26

some cells are immortal because there telomerase is switched on eg blood cells and cancer cells.

Question 27

evidence as to why telomeres can’t be the only reasoning behind cellular senescence

Answer 27

labs have mice with long telomeres such as 30-40kb but live much shorter than humans of 5-15kb telomeres