Multi-Organ Failure, Aging, & Death

Question 1

Defintion: Occurs when too little circulating blood volume causes a decrease in mean arterial pressure (MAP), resulting in the body’s need for oxygen being unmet.

Answer 1

hypovolemic shock

Question 2

What are some causes of hypovolemic shock?

Answer 2

• hemorrhage (internal or external)
• Vomiting
• Diarrhea
• Bowel obstruction, pancreatitis
• Burns
• Neglect, environmental (dehydration)

Question 3

Definition: results when fluid volume moves out of vascular space into extravascular space; “third spacing”

Answer 3

relative hypovolemia

Question 4

Definition: loss of intravascular fluid volume

Answer 4

absolute hypovolemia

Question 5

What are some causes of cariogenic shock?

Answer 5

• Myocardial infarction
• Left ventricular failure
• Right ventricular failure
• Myocardial contusion (trauma)
• Cardiomyopathy
• Myocarditis
• Septic myocardial depression
• Valvular failure (stenotic or regurgitant)
• Hypertropic cardiomyopathy
• Ventricular septal defect
• Electrical failure (arrhythmic)
• Bradycardia/Tachycardia

Question 6

Why does there seem to be an increase in cancer among older patients?

Answer 6

declining function of tumor suppressor genes, particularly P53, which normally triggers apoptosis in cells that have undergone DNA-damaging stress

Question 7

What abnormalities in post-translational changes can cause aberrant proteins in older people?

Answer 7

Glycosylation – adding of carbohydrate groups changes protein function. Abnormalities in this process increases with age.

Cross-linking of various types of macromolecules can also alter their function.

Question 8

Defintion: the idea that some cells are programmed to replicate a finite number of times

Answer 8

program theory

Question 9

What happens to connective tissue with age?

Answer 9

Cross-linking of connective tissue causes a decrease in the elasticity of connective tissues, and has effects on many organs; happens to both collagen and elastin

Question 10

Definition: stretches of repetitive DNA at the ends of chromosomes

Answer 10

telomeres

Question 11

How does telomere shortening contribute to aging?

Answer 11

Since the chromosome cannot be completely copied, the very tips of each chromosome get shorter and shorter with successive cell divisions. When the telomere gets too short for the cell to divide, it either undergoes apoptosis (programmed cell death) or it become senescent – it stops dividing. Enzyme telomerase activity drops with age.

Question 12

Definition: an enzyme that creates new blocks of repetitive DNA sequences, which are added to the tips of the chromosomes, keeping the telomeres from shortening.

Answer 12

telomerase

Question 13

Cells that have a high turnover rate have high levels of telomerase. How does increasing telomerase affect tissue?

Answer 13

One study showed that elevating levels of telomerase in the skin and hair follicles of mice caused them to have healthier skin, better wound healing, and thicker fur. However, they also had a higher rate of skin cancer.

Question 14

Definition: The theory that all systems have a certain amount of reserve capacity, and when the capacity is exhausted, due to injury or damage, the system begins to fail.

Answer 14

Wear and Tear Theory

Question 15

Definition: various materials accumulate in tissues, and this influences their function.
(ex. collagen between myocardial cells, calcium in many different tissues, amyloid in brain cells)

Answer 15

Excessive Accumulation Theory

Question 16

How does aging affect the immune system?

Answer 16

• both innate and adaptive immunity decline, but adaptive immunity is particularly impaired
• older people are less likely to develop fevers; less robust immune response
• more vulnerable to disease, and slower to recover
• less responsive to vaccines – need a stronger version of the flu vaccine

Question 17

How does aging affect responsiveness to temperature?

Answer 17

• less vascular control (to conserve heat)
• loss of subcutaneous fat and hair and thinning of skin increase the rate of heat loss
• less able to exercise to generate heat
• less effective at shivering
• sweating is less effective – sweat glands become fibrotic and function less well

Question 18

How does aging affect the heart?

Answer 18

• the heart is typically remains unchanged or undergoes moderate hypertrophy
• left ventricular wall typically thickens to some extent Igreater in a person with hypertension)
• possible enlargement of the left atrium and of the left ventricular cavity
• thickening of the myocardial wall due to an increase in the size of individual cardiac myocytes
• some replacement of myocytes with fibrous tissue

Question 19

How does aging affect vasculature?

Answer 19

• the walls of their large distributing arteries thicken and arteries become dilated and elongated (result of cellular accumulation and deposition of matrix in the intimate)
• fragmentation of the elastic fibers
• increased the risk of atherosclerosis
• changes in the connective tissue within the media of the vessel wall decrease its elasticity
• increase in collagen and changes in the cross-linking of collagen
• elastin becomes frayed and fragmented

Question 20

How does aging affect cardiac function at rest?

Answer 20

• rate of filling of the left ventricle during diastole is slower, (slowed relaxation of the muscle)
• resting arterial blood pressure tends to increase with age, thereby increasing the afterload
• force of conctraction is not changed in a normal heart
• rate of relaxation is decreased, due to slower pumping of Ca++ back into the sarcoplasmic reticulum.
• resting ejection fraction is unchanged in healthy men and women
• resting stroke volume increases slightly in older men
• supine heart rate is unchanged, but heart rate while sitting decreases slightly
• intrinsic sinus rate (the heart rate in the absence of sympathetic and parasympathetic neural input) drops slightly
• small fall in CO due to the fall in HR in women

Question 21

How does aging affect cardiac function during exercise?

Answer 21

• maximal cardiac output decreases by 25%.
• peripheral oxygen utilization falls as a result of age-associated reductions in muscle mass and strength
• less of an increase in SV with increased EDV.

Question 22

How does aging affect the respiratory system?

Answer 22

• loss of elastic tissue –> loss of elastic recon
• respiratory muscles weaken
• chest wall becomes stiffer due to calcification of intercostal cartilage
• decrease in VC and increase in RV
• decreased airflow
• FEV1 falls by about 23-30 ml/year
• diffusion capacity peaks at age 20 then declines due to alveolar destruction, increased alveolar wall thickness, and small airway closure
• PaO2 declines until age 75
• control of breathing declines due to decreased responsiveness of peripheral and central chemoreceptors

Question 23

What is the effect of aging on the renal system?

Answer 23

• GFR and renal blood flow declines progressively (10%/decade after 30) due primarily to a decreased size of the renal vascular bed
• tubular function is maintained
• renin levels are 30-50% lower in the elderly
• lower aldosterone levels due to lower renin/angiotensin levels
• less able to conserve sodium when on a salt-restricted diet –> increased risk of volume depletion and dehydration
• higher risk for hyperkalemia
• renal concentrating and diluting ability is compromised
• thirst mechanisms appear to be less sensitive.
• secretory mechanisms are impaired, which can interfere with the normal clearance of drugs

Question 24

Definition: irreversible loss of all brain activity, including those essential for life

Answer 24

brain death

Question 25

Definition: a state lacking wakefulness and awareness

Answer 25

coma

Question 26

Definition: an “awake” state that lacks awareness; about 50% of
adults and 60% of children regain consciousness within 6 months; after 1 year, likelihood of recovery is much lower

Answer 26

vegetative state

Question 27

Defintion: one or more devices or procedures that keep a patient alive. Includes mechanical ventilation, feed tubes, dialysis, heart-lung bypass, etc.

Answer 27

life support

Question 28

What is cachexia?

Answer 28

often seen in cancer patients; a set of metabolic changes that results in loss of weight, particularly muscle mass, compounding the consequences of loss of appetite

Question 29

Definition: a pattern of increasingly shallow breaths, followed by a brief cessation of breathing, followed by a few strong deep breaths. The pattern repeats itself until the patient stops breathing

Answer 29

Cheyne-Stokes breathing

Question 30

Defintion: resonant sounds due to fluid accumulation deep in the lungs

Answer 30

Death rattle

Question 31

What are some characteristics that are present 48 hours before death or “active dying”?

Answer 31

• Cheyne-Stokes breathing
• death rattle
• loss of appetite and thirst
• sweating – clammy skin
• fall in body temperature of 1-2 degrees
• mottled skin, especially at extremities reflecting circulatory failure

Question 32

Defintion: just providing appropriate comfort care for a dying patient; this might be just food and water and pain medication for a patient who in their last weeks of life.

Answer 32

palliative care

Question 33

Defintion: focuses on providing comfort care through the dying process, and on meeting the emotional and spiritual needs of patients and their families; patients may be cared for in their homes or in home-like institutional settings

Answer 33

hospice care

Question 34

When is hospice care appropriate?

Answer 34

for people whose terminal illness progresses in a predictable way

Question 35

What are the top 4 causes of death in the US?

Answer 35

1. heart disease
2. cancer
3. chronic lower respiratory disease
4. stroke