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Chapter 7
The Physiology and Pathology of Aging

Objectives (1 of 2)

Differentiate between average life expectancy and maximum life span.

Compare and contrast the genetic and environmental theories of aging.

Explain the possible role of free radical formation in the aging process.

Objectives (2 of 2)

Identify common age-related changes related to the cardiovascular, respiratory, gastrointestinal, genitourinary, musculoskeletal, nervous, sensory, endocrine, immune and integumentary systems.

Discuss health promotion for the aging process in relation to prevalent chronic diseases.

Introduction (1 of 5)

  • Average life expectancy
  • Rose from 47.3 years in 1900 to 78.8 years in 2015
  • No change in the maximum life span during the same period

Introduction (2 of 5)

Introduction (3 of 5)

  • Unchanging MLS coupled with increasing life expectancy:
  • Supports the notion of distinguishing disease from aging
  • Points to the existence of a “biological clock” that predetermines humans’ length of life

Introduction (4 of 5)

  • Fixed life span does not necessarily sentence adults to pain and suffering as they get older
  • Many physiologic changes associated with aging can be slowed with a healthy diet and moderate exercise
  • Many chronic diseases are preventable or modifiable with healthy lifestyle habits

Introduction (5 of 5)

Theories of Aging (1 of 2)

  • Programmed theories of aging
  • Somatic mutation theory
  • Varying rates of mutagenesis and proficiencies of DNA repair may affect longevity
  • Endocrine theory
  • Biological clocks and hormone regulation control the rate of aging
  • Immunological theory
  • Immune system is “coded” to erode over time

Theories of Aging (2 of 2)

  • Environmental theories of aging
  • Wear-and-tear theory
  • Aging is inevitable as cells, tissues, and organs wear out from continued use
  • Rate-of-living theory
  • Attributes variation in life span to varying metabolic rates per gram of metabolizing tissue across species
  • Free radical theory
  • Attributes cellular aging free radicals

Physiological Changes of Aging (1 of 52)

  • Cardiovascular system
  • Responsible for circulation of blood
  • Damage to this system can have negative implications for the entire body
  • Ventricles generate pressure that propels blood through arteries, arterioles, capillaries, venules, and veins

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Physiological Changes of Aging (2 of 52)

Physiological Changes of Aging (3 of 52)

  • Cardiovascular disease (CVD)
  • One of the leading causes of death
  • Atherosclerosis
  • Development of fatty plaques and proliferation of connective tissue in arterial walls
  • Heart requires additional time to perform basic functions and has more difficulty regulating blood pressure

Physiological Changes of Aging (4 of 52)

Physiological Changes of Aging (5 of 52)

  • Complications of atherosclerosis can include:
  • Myocardial infarction (heart attack)
  • Stroke
  • Hypertension and kidney failure
  • Claudication, deep vein thrombosis (DVT), and ulcerations of the skin

Physiological Changes of Aging (6 of 52)

  • Risk factors for atherosclerosis:
  • Older age
  • Genetic predisposition
  • Hypertension
  • Diabetes mellitus
  • High blood cholesterol level
  • Cigarette smoking
  • Obesity and poor physical fitness
  • “Type A” personality

Physiological Changes of Aging (7 of 52)

  • Heart attack
  • Warning signs are not always obvious in older adults and individuals with diabetes mellitus
  • Common signs:
  • Chest pain/pressure
  • Discomfort in the arms, back, neck, jaw, or stomach
  • Shortness of breath
  • Lightheadedness
  • Nausea and sweating

Physiological Changes of Aging (8 of 52)

  • Prevention of cardiovascular disease
  • Maintain a proper diet
  • Exercise regularly
  • Maintain a healthy weight
  • Manage stress
  • Avoid cigarettes
  • Schedule annual physicals

Physiological Changes of Aging (9 of 52)

  • Respiratory system
  • Transports oxygen to, and removes carbon dioxide from, the bloodstream
  • From the lungs, inhaled air continues through smaller bronchi, bronchioles, and alveolar ducts to the alveoli, the site of gas exchange

Physiological Changes of Aging (10 of 52)

Physiological Changes of Aging (11 of 52)

  • Lung tissue changes as we age, and the rib cage stiffens
  • Older adults experience shortness of breath more quickly during exercise
  • May also lower one’s tolerance for exercise

Physiological Changes of Aging (12 of 52)

  • Respiratory health problems:
  • Chronic obstructive pulmonary disease (COPD)
  • Emphysema and chronic bronchitis together
  • Pneumonia
  • Lung cancer
  • COPD and lung cancer are primarily caused by cigarette smoking

Physiological Changes of Aging (13 of 52)

  • Gastrointestinal system
  • Processes incoming food so nutrients can be absorbed into the body
  • Primary structural feature is the digestive tract
  • Aging has minimal effects on the digestive system

Physiological Changes of Aging (14 of 52)

Physiological Changes of Aging (15 of 52)

  • Changes and conditions that can affect the digestive system as we age:
  • Teeth become discolored and worn
  • Xerostomia (dry mouth)
  • Dysphagia (difficulty swallowing)
  • Peptic ulcers and gastritis
  • Gallstones, cholecystitis, and pancreatitis
  • Decreased ability of the liver to detoxify

Physiological Changes of Aging (16 of 52)

  • Changes and conditions that can affect the digestive system as we age (continued):
  • Diverticulosis
  • Fecal incontinence
  • Atherosclerosis affecting the small and large intestines
  • Colorectal cancer

Physiological Changes of Aging (17 of 52)

  • Genitourinary system
  • Consists of the kidneys and urinary tract
  • Functions of the kidneys:
  • Excretion of waste products
  • Maintenance of homeostasis in the fluid compartments of the body

Physiological Changes of Aging (18 of 52)

  • Excretion of waste
  • Kidney filtration decreases as nephrons become less efficient and fewer in number with aging
  • Because kidneys also help eliminate medications, drug dosages for older adults are smaller than for younger individuals

Physiological Changes of Aging (19 of 52)

  • Maintaining homeostasis in fluid compartments
  • Ability to regulate the concentration of bodily substances diminishes with age
  • Older adults more susceptible to dehydration

Physiological Changes of Aging (20 of 52)

Physiological Changes of Aging (21 of 52)

  • Urinary incontinence
  • Not uncommon among older adults
  • Can be caused by:
  • Lowered estrogen levels in women
  • Multiple pregnancies
  • Enlarged prostate gland
  • Distended and weakened bladder

Physiological Changes of Aging (22 of 52)

  • Nocturia
  • Frequent urination at night
  • Contributing factors:
  • Adverse effects of medications
  • Chronic conditions such as cardiac disease, diabetes, obesity, and sleep disorders

Physiological Changes of Aging (23 of 52)

  • Musculoskeletal system
  • Musculoskeletal dysfunction is a major cause of disability in older adults, altering:
  • Mobility
  • Fine motor control
  • Mechanics of respiration

Physiological Changes of Aging (24 of 52)

  • Changes that occur with aging:
  • Decline in muscle mass
  • Decreased reflexes
  • Loss of cartilage
  • Thinning of vertebrae
  • Decreased calcium absorption
  • Joint cartilage deterioration
  • Deterioration of the extrapyramidal system

Physiological Changes of Aging (25 of 52)

  • Changes in the musculoskeletal system increase the likelihood of:
  • Falls
  • Respiratory infections
  • General physiologic decline
  • Osteoporosis
  • Reduction in bone mass and bone density
  • Predisposes an individual to fractures

Physiological Changes of Aging (26 of 52)

  • Risk factors for osteoporosis:
  • Estrogen depletion (postmenopausal women)
  • Calcium deficiency
  • Decreased bone mass
  • Physical inactivity
  • Testosterone depletion (males)
  • Alcohol dependence
  • Cigarette smoking and tobacco use

Physiological Changes of Aging (27 of 52)

  • Osteoarthritis
  • Also called degenerative joint disease (DJD)
  • Prevalence increases with age
  • Marked by ulceration and destruction of joint cartilage
  • Most commonly affects weight-bearing joints
  • Symptoms include pain, swelling, and decreased range of motion

Physiological Changes of Aging (28 of 52)

  • Changes in skeletal muscle with age:
  • Number of skeletal muscle fibers decreases
  • Muscle fiber size decreases
  • Capillary supply decreases
  • Deposition of lipofuscin and adipose cells increases
  • Spotty loss of motor neuron innervation

Physiological Changes of Aging (29 of 52)

  • Nervous system
  • Central nervous system (CNS)
  • Principal regulatory system of the body
  • Consists of brain, brain stem, and spinal cord
  • Regulates and monitors peripheral activities via the cranial nerves
  • Basic functional unit is the neuron

Physiological Changes of Aging (30 of 52)

  • Changes in the nervous system with age:
  • Lose nerve cell mass
  • Some brain atrophy
  • Nerve cells and dendrites decline in number, slowing the transformation of information and weakening reflexes
  • Brain weight decreases

Physiological Changes of Aging (31 of 52)

  • Neurotransmitters
  • Characterized as excitatory or inhibitory
  • Well-characterized neurotransmitters include:
  • Acetylcholine
  • Dopamine
  • Gamma-aminobutyric acid (GABA)
  • Serotonin
  • Smooth nervous system functioning relies on balanced activity among neurotransmitters

Physiological Changes of Aging (32 of 52)

  • Memory
  • Mild loss of memory and recall for recent events is common with age
  • Long-term memory remains intact
  • Early stages of dementia mimic normal memory loss of aging

Physiological Changes of Aging (33 of 52)

  • Intelligence
  • Crystallized intelligence can continue to increase with age
  • Fluid intelligence decreases with age
  • Overall intelligence, measured by an intelligence quotient, remains fairly stable throughout adult life

Physiological Changes of Aging (34 of 52)

  • Motor function
  • Symptoms of impaired locomotor function:
  • Slowing of fine motor tasks
  • Diminished postural reflexes
  • Decreased gross motor skills
  • Motor control is also influenced by diminished sensory input
  • Older adults face a greater risk of falls

Physiological Changes of Aging (35 of 52)

  • Sleep
  • About half of the older population reports difficulty falling or staying asleep
  • Sleep becomes shorter but more frequent
  • Sleep disturbances
  • May be caused by insomnia, neurological conditions, breathing disorders, pain, medical diagnosis, and medications
  • Tend to affect the deepest levels of sleep

Physiological Changes of Aging (36 of 52)

  • Endocrine system
  • Helps control:
  • Body temperature
  • Basal metabolic rate
  • Growth rate
  • Carbohydrate, lipid, and protein metabolism
  • Stress responses
  • Reproduction

Physiological Changes of Aging (37 of 52)

  • Endocrine system (continued)
  • Collection of glands that produce and secrete hormones into the bloodstream
  • Hormones have physiologic effects on specific target organs
  • There is a hierarchical control of the release of most hormones that begins in the CNS

Physiological Changes of Aging (38 of 52)

Physiological Changes of Aging (39 of 52)

  • Effects of aging on the endocrine system
  • Thyroid hormone production decreases
  • Rate of removal of thyroid hormone decreases
  • Androgen and estrogen production decreases
  • Aldosterone levels fall
  • Takes longer to reestablish normal blood cortisol levels after a stressful event
  • Increased risk of type II diabetes

Physiological Changes of Aging (40 of 52)

  • Immune system
  • Protects the body from infections and cancer
  • Body develops “immunological memory” after recovering from infection by a pathogen
  • Age-related decline gives rise to:
  • Infections
  • Cancer
  • Autoimmune disease

Physiological Changes of Aging (41 of 52)

  • Integumentary system
  • Consists of the skin and its accessory structures
  • Changes are visibly noticeable
  • Layers of the skin:
  • Epidermis
  • Dermis
  • Subcutaneous

Physiological Changes of Aging (42 of 52)

Regula H. Robnett

Physiological Changes of Aging (43 of 52)

  • Effects of aging on the skin:
  • Rate of skin regeneration decreases
  • Number of melanocytes decreases
  • Amounts of collagen and elastin decrease
  • Density of the dermal blood supply decreases
  • Sweat gland function decreases
  • Gradual loss of sensory receptors
  • Thinning of the subcutaneous layer

Physiological Changes of Aging (44 of 52)

Physiological Changes of Aging (45 of 52)

  • Sun exposure
  • Chronic overexposure is associated with:
  • Wrinkling
  • Coarseness
  • Irregular pigmentation
  • Development of lesions
  • Skin cancer
  • Some sun exposure necessary for vitamin D production

Physiological Changes of Aging (46 of 52)

  • Hair
  • Aging is associated with graying, thinning, and loss of hair
  • Number of hair follicles decreases with age
  • Remaining follicles grow at slower rates and contain lower concentrations of melanin
  • Reduces hair’s protective ability to screen the scalp from sunlight

Physiological Changes of Aging (47 of 52)

  • Sensory organs
  • Vision
  • Visual acuity decreases with aging with the gradual loss of cones and rods
  • Lens also becomes thicker, causing blurry vision, night vision issues, and sensitivity to glare
  • Elasticity of the lens decreases, causing presbyopia
  • Aging is also associated with cataracts, macular degeneration, glaucoma, and diabetic retinopathy

Physiological Changes of Aging (48 of 52)

Physiological Changes of Aging (49 of 52)

  • Hearing
  • Hearing impairment is the most common condition in older adults
  • Progressive hearing loss is called presbycusis
  • Loss of high-frequency hearing makes it difficult to hear consonants
  • Changes in hearing can cause speech to sound muffled

Physiological Changes of Aging (50 of 52)

Physiological Changes of Aging (51 of 52)

  • Taste
  • Can be affected by:
  • Medications
  • Increase or decrease in saliva production
  • Oral disorders
  • Chronic disease
  • No decrease in taste buds with age
  • Taste sensations undergo different changes during the aging process

Physiological Changes of Aging (52 of 52)

  • Smell
  • Functional decline can lead to hyposmia or anosmia
  • Decline in numbers of mucosal sensory cells and olfactory bulb relay cells in later life account for decreased sensitivity to smell
  • Hyposmia can make food less desirable
  • Anosmia can impair one’s ability to detect toxic odors, spoiled food, or a fire in the home