BIOL204 Lecture 26 Section C (Final)

What is senescence?

a state of irreversible growth arrest that a cell undergoes

Is senescence synonymous with aging?

related but not entirely, aging is a broader term

What is the purpose of senescence?

act as a tumor suppressor by stopping cells from dividing; heals woulds and develops embryos by shaping tissues and organs

What are the three main types of cellular senescence?

replicative, oncogene-induced, and DNA damage-induced senescences

Do senescent cells cease to divide?

yes, they stop dividing and are arrested in the cell cycle

What does replicative senescence state?

further division of cells is stopped to prevent loss of vital genetic information

What are telomeres?

protective caps on the ends of chromosomes that prevent them from fraying and losing genetic information during cell division

What happens to the telomeres in each round of DNA replication?

they become progressively shorter

Which genes activate senscence in the oncogene-induced theory?

oncogenes

Which genes lead to sesenscence when they are inactivated?

tumor suppressors

How is cellular senescence produced according to the oncogene-induced senescence theory?

from the presence of oncogenes that promote uncontrolled cell division that causes senescence to be triggered as a defense mechanism

What is the role of DNA damage induced senescence?

a protective mechanism that prevents the flawed DNA from being replicated and passed on

How does DNA damage accumulate during aging despite the presence of DNA repair enzymes?

DNA repair enzymes are not perfect and miss some damaged cells

Which intrinsic and extrinsic factors can cause DNA damage in a cell ?

reactive oxygen species, chemical toxins, replication errors

What are reactive oxygen species?

highly reactive molecules containing at least one oxygen atom and one or more unpaired electrons

How do the muscular and skeletal systems change as we age?

decreased muscular mass and strength, reduced bone deposition, decreased bone mineral density, weakened bones, increased risk of fracture, degenerative changes in joints

How does the urinary system change as we age?

decrease in the GFR

How is the liver affected as we age?

decreased volume, blood flow, and first-pass metabolism

How does the nervous system change as we age?

impairment of body coordination, memory, and intellectual function

How does the cardiovascular system change as we age?

decrease in cardiac output, development of myocardial hypertrophy, heart conduction abnormalities, increased arterial stiffness

How does the digestive system change as we age?

decrease in peristalsis and muscle tone along the digestive tract

How does the endocrine system change as we age?

decrease in production of hormones and organ sensitivity to them

How does the skin change as we age?

loss of elasticity, producing sagging and wrinkling

What happens to the immune system as we age?

fewer immune cells, decreased T cell function, weaker antibody response, increased autoimmunity, delayed wound healing, increased susceptibilityto infections and cancer

Why are elderly patients more at risk of fractures?

bone loss with age, increased fall risk

What is myocardial hypertrophy?

enlargement/thickening of the myocardium

What is arterial stiffness?

reduced ability of arteries to expand and contract in response to changes in blood pressure

What makes older adults more susceptible to infections?

age-related changes in their immune system

What causes wrinkled to become more noticeable in older individuals?

decreased collagen and elastin production, reduced skin cell turnover, hyaluronic acid levels decrease with age