1 Chapter 29 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright (c) The McGraw-Hill.

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Chapter 29Chapter 29

Lecture OutlineLecture Outline

See PowerPoint Image SlidesSee PowerPoint Image Slides

for all figures and tables pre-inserted intofor all figures and tables pre-inserted into

PowerPoint without notes.PowerPoint without notes.

Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

22

Human DevelopmentHuman Development

Fertilization and Pre-embryonic StageFertilization and Pre-embryonic Stage Embryonic and Fetal StagesEmbryonic and Fetal Stages The NeonateThe Neonate Aging and SenescenceAging and Senescence

33

Sperm MigrationSperm Migration

Majority of sperm do not make it to eggMajority of sperm do not make it to egg destroyed by vaginal aciddestroyed by vaginal acid fail to penetrate the cervical canal mucusfail to penetrate the cervical canal mucus go up wrong uterine tubego up wrong uterine tube

Move by lashing of sperm tailMove by lashing of sperm tail Assisted by female physiologyAssisted by female physiology

strands of cervical mucusstrands of cervical mucus uterine contractionsuterine contractions chemical attraction chemical attraction

44

CapacitationCapacitation Spermatozoa reach uterine tube within 10 Spermatozoa reach uterine tube within 10

minutes of ejaculationminutes of ejaculation to fertilize egg must undergo capacitationto fertilize egg must undergo capacitation

takes 10 hourstakes 10 hours female fluids wash away inhibitory factorsfemale fluids wash away inhibitory factors sperm membrane becomes fragile and permeable to sperm membrane becomes fragile and permeable to

CaCa2+2+

Sperm fertile for 48 hours after ejaculationSperm fertile for 48 hours after ejaculation Conception optimal if sperm are deposited 48 Conception optimal if sperm are deposited 48

hours before ovulation to 14 hours afterhours before ovulation to 14 hours after

55

FertilizationFertilization Acrosomal reaction of capacitated spermAcrosomal reaction of capacitated sperm

release of enzymes from many sperm needed release of enzymes from many sperm needed penetrates granulosa cells then zona pellucida surrounding egg penetrates granulosa cells then zona pellucida surrounding egg hyaluronidase and acrosin hyaluronidase and acrosin

membranes of 2 gametes fuse and sperm entersmembranes of 2 gametes fuse and sperm enters

Prevention of polyspermyPrevention of polyspermy fast block - depolarization of membrane (opening of Nafast block - depolarization of membrane (opening of Na++

channels) prevents binding of second spermchannels) prevents binding of second sperm slow block - sperm penetration triggers Caslow block - sperm penetration triggers Ca2+2+ inflow, causes inflow, causes

cortical reaction (secretion from cortical granules forms cortical reaction (secretion from cortical granules forms fertilization membrane)fertilization membrane)

66

FertilizationFertilization

77

FertilizationFertilization Secondary oocyte Secondary oocyte

completes meiosis completes meiosis if fertilizedif fertilized produces 2produces 2ndnd polar polar

bodybody

Swollen sperm and Swollen sperm and egg nuclei called egg nuclei called pronucleipronuclei

Pronuclei rupturePronuclei rupture Chromosomes of 2 Chromosomes of 2

gametes mix gametes mix Fertilized egg now Fertilized egg now

called a zygotecalled a zygote

88

Pre-embryonic Stage - First 2 Pre-embryonic Stage - First 2 WeeksWeeks Cleavage - mitotic divisions that occur for 3 days Cleavage - mitotic divisions that occur for 3 days

after fertilizationafter fertilization within 30 hrs – 2 cell stagewithin 30 hrs – 2 cell stage

zygote splits into 2 daughter cells (blastomeres)zygote splits into 2 daughter cells (blastomeres)

within 72 hrs – morula stage (solid ball of cells)within 72 hrs – morula stage (solid ball of cells)

Morula free in uterine cavity for 4-5 daysMorula free in uterine cavity for 4-5 days nourished by endometrial secretion (uterine milk)nourished by endometrial secretion (uterine milk)

Zona pellucida disintegrates to release blastocystZona pellucida disintegrates to release blastocyst outer cells (trophoblast) helps to form placentaouter cells (trophoblast) helps to form placenta inner cell mass (embryoblast) develops into embryoinner cell mass (embryoblast) develops into embryo

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From Ovulation to ImplantationFrom Ovulation to Implantation

Fig. 29.2

1010

TwinsTwins Dizygotic (fraternal) twinsDizygotic (fraternal) twins

2 eggs are ovulated and fertilized (2 zygotes)2 eggs are ovulated and fertilized (2 zygotes) as different as any other siblingsas different as any other siblings

Monozygotic (maternal) twinsMonozygotic (maternal) twins 1 egg is fertilized (1 zygote) but embryoblast 1 egg is fertilized (1 zygote) but embryoblast

splits into twosplits into two genetically identical siblings (must be same sex)genetically identical siblings (must be same sex)

1111

Dizygotic TwinsDizygotic Twins

1212

Implantation of BlastocystImplantation of Blastocyst

Attaches to uterine wall 6 days after ovulationAttaches to uterine wall 6 days after ovulation Syncytiotrophoblast - multinucleate mass grows Syncytiotrophoblast - multinucleate mass grows

“roots” and digests its way into endometrium“roots” and digests its way into endometrium secretes human chorionic gonadotropin (HCG) secretes human chorionic gonadotropin (HCG) becomes chorionbecomes chorion

Endometrium completely encloses embryoEndometrium completely encloses embryo

1313

Steps of EmbryogenesisSteps of Embryogenesis Arrangement of blastomeres into 3 Arrangement of blastomeres into 3

primary germ layersprimary germ layers Formation of amniotic cavity Formation of amniotic cavity

between embryoblast and between embryoblast and cytotrophoblastcytotrophoblast

Flattening of embryoblast into Flattening of embryoblast into embryonic disc formed from embryonic disc formed from ectodermal and endodermal cellsectodermal and endodermal cells

Cells sink into primitive streak Cells sink into primitive streak (a groove) and spread laterally as (a groove) and spread laterally as mesoderm layer mesoderm layer gelatinous tissue (mesenchyme cells)gelatinous tissue (mesenchyme cells)

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Implanted Conceptus at 2 Implanted Conceptus at 2 WeeksWeeks

1515

Ectopic PregnancyEctopic Pregnancy

Blastocyst implants outside uterusBlastocyst implants outside uterus 1 out of 300 pregnancies1 out of 300 pregnancies most cases occur in uterine tube (tubal pregnancy)most cases occur in uterine tube (tubal pregnancy)

occurs because of tubal obstruction from previous pelvic occurs because of tubal obstruction from previous pelvic inflammations, repeated abortions or tubal surgeryinflammations, repeated abortions or tubal surgery

Tube ruptures by 12 weeksTube ruptures by 12 weeks conceptus may reimplant in abdominopelvic cavityconceptus may reimplant in abdominopelvic cavity

anywhere it finds an adequate blood supplyanywhere it finds an adequate blood supply usually requires an abortionusually requires an abortion

9% of abdominal pregnancies result in live birth by 9% of abdominal pregnancies result in live birth by cesarian sectioncesarian section

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Embryonic Stage or Weeks 2 to Embryonic Stage or Weeks 2 to 99

Begins when all 3 primary germ layers presentBegins when all 3 primary germ layers present Conceptus forms a set of membranes external to Conceptus forms a set of membranes external to

embryoembryo Embryo begins receiving its nutrients from Embryo begins receiving its nutrients from

placentaplacenta Germ layers differentiate into organs and organ Germ layers differentiate into organs and organ

systemssystems presence of organs marks the beginning of fetal stagepresence of organs marks the beginning of fetal stage

1717

PlacentationPlacentation Formation of placenta occurs from 11 days to 12 Formation of placenta occurs from 11 days to 12

weeksweeks Chorionic villi Chorionic villi

extensions of syncytiotrophoblast into endometrium by extensions of syncytiotrophoblast into endometrium by digestion and growth of “roots” of tissuedigestion and growth of “roots” of tissue

mesenchyme extends into chorionic villi to form embryonic mesenchyme extends into chorionic villi to form embryonic blood vesselsblood vessels

Placental sinus Placental sinus pools of maternal blood that merge and surround villipools of maternal blood that merge and surround villi blood stimulates rapid growth of chorionic villiblood stimulates rapid growth of chorionic villi

1818

Stages of Placental DevelopmentStages of Placental Development

1919

Placenta and Embryonic Placenta and Embryonic MembranesMembranes

2020

Placenta and Embryonic Placenta and Embryonic MembranesMembranes

2121

The PlacentaThe Placenta Once fully developed - 20 cm diameter and 3 cm Once fully developed - 20 cm diameter and 3 cm

thick disc thick disc Surface facing fetus is smooth and connected to Surface facing fetus is smooth and connected to

fetus by umbilical cordfetus by umbilical cord Uterine surface consists of villi and decidua basalis Uterine surface consists of villi and decidua basalis

region of endometrium region of endometrium Fetal and maternal blood do not mixFetal and maternal blood do not mix Placental conductivity increases as villi grow Placental conductivity increases as villi grow

substances pass through by diffusion, facilitated diffusion, substances pass through by diffusion, facilitated diffusion, active transport and receptor-mediated endocytosisactive transport and receptor-mediated endocytosis

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Embryonic MembranesEmbryonic Membranes

Amnion - transparent sac filled with fluidAmnion - transparent sac filled with fluid protects embryo from trauma, temperature changes, protects embryo from trauma, temperature changes,

adhesions and provides freedom of movementadhesions and provides freedom of movement forms from maternal plasma filtrate and fetal urineforms from maternal plasma filtrate and fetal urine at term, amnion contains 700 to 1000 mL of fluidat term, amnion contains 700 to 1000 mL of fluid

Yolk sac - hangs from ventral side of embryoYolk sac - hangs from ventral side of embryo contribute to GI tract, blood cells and germ cellscontribute to GI tract, blood cells and germ cells

Allantois - foundation of umbilical cord and urinary Allantois - foundation of umbilical cord and urinary bladderbladder

Chorion - outermost membrane Chorion - outermost membrane chorionic villi form fetal portion of the placentachorionic villi form fetal portion of the placenta

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Embryonic MembranesEmbryonic Membranes

2424

OrganogenesisOrganogenesis Formation of organs from primary germ layersFormation of organs from primary germ layers

at 8 weeks, all organs are present in 3 cm long fetusat 8 weeks, all organs are present in 3 cm long fetus heart is beating and muscles exhibit contracts heart is beating and muscles exhibit contracts

Derivatives of ectodermDerivatives of ectoderm epidermis, nervous system, lens and cornea, internal earepidermis, nervous system, lens and cornea, internal ear

Derivatives of mesodermDerivatives of mesoderm skeleton, muscle, cartilage, blood, lymphoid tissue, skeleton, muscle, cartilage, blood, lymphoid tissue,

gonads and ducts, kidneys and uretersgonads and ducts, kidneys and ureters

Derivatives of endodermDerivatives of endoderm gut and respiratory epithelium and glands, bladder and gut and respiratory epithelium and glands, bladder and

urethraurethra

2525

Embryonic DevelopmentEmbryonic Development

2626

Fetal Development and CirculationFetal Development and Circulation Fetus = from 8 weeks until birthFetus = from 8 weeks until birth

organs mature to support external lifeorgans mature to support external life Anatomical changes in fetal circulationAnatomical changes in fetal circulation

spaces in mesoderm become lined with spaces in mesoderm become lined with endothelium and merge into blood vessels endothelium and merge into blood vessels and lymphatic vesselsand lymphatic vessels

side-by-side endothelial tubes fuse to form heartside-by-side endothelial tubes fuse to form heart Fetal circulationFetal circulation

umbilical-placental circuit via umbilical cordumbilical-placental circuit via umbilical cord circulatory shuntscirculatory shunts

ductus venosus connects to inferior vena cavaductus venosus connects to inferior vena cava foramen ovale connecting right and left atriaforamen ovale connecting right and left atria ductus arteriosus connects pulmonary trunk to aortaductus arteriosus connects pulmonary trunk to aorta

2727

Blood Circulation Before and After BirthBlood Circulation Before and After Birth

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The Neonate or NewbornThe Neonate or Newborn Transitional periodTransitional period

first 6-8 hours heart and respiratory rate first 6-8 hours heart and respiratory rate and body and body temperature fallstemperature falls

periods of sleeping and gagging on mucus and debrisperiods of sleeping and gagging on mucus and debris feed every 3 to 4 hours during 6 week neonatal periodfeed every 3 to 4 hours during 6 week neonatal period

Respiratory adaptations of newbornRespiratory adaptations of newborn onset of breathing due to COonset of breathing due to CO22 accumulation accumulation great effort to inflate lungs for first few breathsgreat effort to inflate lungs for first few breaths

Immunological adaptationImmunological adaptation maternal antibody, IgG, diffuses across placentamaternal antibody, IgG, diffuses across placenta

provides 6 mo of protection from most infectious diseases while provides 6 mo of protection from most infectious diseases while fetal production fetal production

IgA in breast milk can protect newborn from gastroenteritisIgA in breast milk can protect newborn from gastroenteritis

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Circulatory AdaptationsCirculatory Adaptations Umbilical arteries Umbilical arteries

and veins become and veins become ligamentousligamentous

Ligamentum Ligamentum venosum (liver)venosum (liver)

Fossa ovalis Fossa ovalis (heart)(heart)

Ligamentum Ligamentum arteriosum arteriosum (vessels)(vessels)

3030

Thermoregulation and Fluid Thermoregulation and Fluid BalanceBalance

Infant has larger ratio of surface area to volumeInfant has larger ratio of surface area to volume loses heat more easilyloses heat more easily defensesdefenses

brown fat deposited during weeks 17 to 20 fetal lifebrown fat deposited during weeks 17 to 20 fetal life mitochondria breakdown pyruvic acid and release only heatmitochondria breakdown pyruvic acid and release only heat

grows and increases metabolic rategrows and increases metabolic rate accumulates subcutaneous fataccumulates subcutaneous fat

Kidneys not fully developed at birthKidneys not fully developed at birth can not concentrate urine so have a high rate of water can not concentrate urine so have a high rate of water

loss and require more fluid intake, relative to body loss and require more fluid intake, relative to body weightweight

3131

Premature InfantsPremature Infants

Infants born weighing under 5.5 lb.Infants born weighing under 5.5 lb. Infants born before 7 months suffer from Infants born before 7 months suffer from

respiratory distress syndromerespiratory distress syndrome insufficient surfactant causing alveolar collapse with exhalationinsufficient surfactant causing alveolar collapse with exhalation

thermoregulatory problems due to undeveloped thermoregulatory problems due to undeveloped hypothalamus -- keep in incubatorhypothalamus -- keep in incubator

digestive system not well developed must be fed low-fat digestive system not well developed must be fed low-fat formula instead of breast milkformula instead of breast milk

immature liver fails to synthesize plasma proteinsimmature liver fails to synthesize plasma proteins edema, deficiency of clotting and jaundice from bileedema, deficiency of clotting and jaundice from bile

3232

Congenital AnomaliesCongenital Anomalies Infectious diseasesInfectious diseases

microorganisms that can cross the placenta includemicroorganisms that can cross the placenta include herpes simplex, rubella, cytomegalovirus, HIVherpes simplex, rubella, cytomegalovirus, HIV

results range from mild effects to blindness, cerebral palsy results range from mild effects to blindness, cerebral palsy and severe physical and mental retardation are just some and severe physical and mental retardation are just some of the resultsof the results

Teratogens are viruses, chemicals or other agents Teratogens are viruses, chemicals or other agents that cause anatomical deformities in fetusthat cause anatomical deformities in fetus thalidomide (unformed arms or legs)thalidomide (unformed arms or legs) fetal alcohol syndrome, smoking and X raysfetal alcohol syndrome, smoking and X rays

cardiac and CNS defects, anencephaly, cleft lip and palate, cardiac and CNS defects, anencephaly, cleft lip and palate, hyperactivity and poor attention spanhyperactivity and poor attention span

3333

Effects of ThalidomideEffects of Thalidomide

Sleeping medication taken early in pregnancy with severe teratogen effects on limb development.

3434

Mutagens and Genetic AnomaliesMutagens and Genetic Anomalies Mutagen is any agent that alters DNA or Mutagen is any agent that alters DNA or

chromosome structurechromosome structure radiation or diverse chemicalsradiation or diverse chemicals

Most common genetic disorders from failure of Most common genetic disorders from failure of homologous chromosomes to separate during homologous chromosomes to separate during meiosis (normal separation = disjunction)meiosis (normal separation = disjunction)

Nondisjunction – unequal # of chromosomes go to Nondisjunction – unequal # of chromosomes go to daughter cells causing aneuploidy (wrong #)daughter cells causing aneuploidy (wrong #) can be detected prior to birth with amniocentesis can be detected prior to birth with amniocentesis

(examining fetal cells from amniotic fluid) or chorionic (examining fetal cells from amniotic fluid) or chorionic villus sampling (examine placental cells)villus sampling (examine placental cells)

3535

Normal Disjunction of X ChromosomesNormal Disjunction of X Chromosomes

3636

Nondisjunction of X ChromosomesNondisjunction of X Chromosomes

3737

Nondisjunction and AneuploidyNondisjunction and Aneuploidy Nondisjunction of sex chromosomesNondisjunction of sex chromosomes

Triplo-X syndrome (XXX) -- egg receiving 2 X Triplo-X syndrome (XXX) -- egg receiving 2 X chromosomes fertilized by X carrying spermchromosomes fertilized by X carrying sperm infertile female with mild intellectual impairmentinfertile female with mild intellectual impairment

Klinefelter syndrome (XXY) -- egg receiving 2 X Klinefelter syndrome (XXY) -- egg receiving 2 X chromosomes fertilized by Y carrying spermchromosomes fertilized by Y carrying sperm sterile males with average intelligence (undeveloped testes)sterile males with average intelligence (undeveloped testes)

Turner syndrome (XO) -- egg receiving no X Turner syndrome (XO) -- egg receiving no X chromosomes but fertilized by X carrying spermchromosomes but fertilized by X carrying sperm sterile, webbed neck, female with no 2nd sexual featuressterile, webbed neck, female with no 2nd sexual features

Nondisjunction of autosomes – often lethalNondisjunction of autosomes – often lethal Most survivable type is Down syndrome (trisomy-21)Most survivable type is Down syndrome (trisomy-21)

3838

Down Syndrome CharacteristicsDown Syndrome Characteristics

Effects of carrying 3 copies of chromosome 21 include: short Effects of carrying 3 copies of chromosome 21 include: short stature, flat face with epicanthal folds on eyes, enlarged stature, flat face with epicanthal folds on eyes, enlarged tongue, stubby fingers and mental retardationtongue, stubby fingers and mental retardation

Occurs in proportion to age of motherOccurs in proportion to age of mother

3939

Aging and SenescenceAging and Senescence Aging is all changes occurring with the passage of Aging is all changes occurring with the passage of

time -- growth, development and degenerationtime -- growth, development and degeneration Senescence is the degeneration that occurs after the Senescence is the degeneration that occurs after the

age of peak functional efficiencyage of peak functional efficiency leading causes of death from 18 to 34 is accidents, leading causes of death from 18 to 34 is accidents,

homicides, suicides and AIDShomicides, suicides and AIDS leading causes of death after 55 is senescence relatedleading causes of death after 55 is senescence related

cancer, stroke, diabetes, heart and lung diseasecancer, stroke, diabetes, heart and lung disease

All organ systems do not degenerate at the same All organ systems do not degenerate at the same rate - some changes not evident except under stressrate - some changes not evident except under stress

4040

Aging of Integumentary SystemAging of Integumentary System Becomes noticeable in late 40sBecomes noticeable in late 40s Intrinsic aging of skinIntrinsic aging of skin gray, thinning, dry hairgray, thinning, dry hair

paper-thin, loose skin that sagspaper-thin, loose skin that sags skin that bruises easily and heals slowly skin that bruises easily and heals slowly hypothermia in cold weather and heat hypothermia in cold weather and heat

stroke in hotstroke in hot atrophy of cutaneous vessels, sweat glands and subcutaneous fatatrophy of cutaneous vessels, sweat glands and subcutaneous fat

vitamin D production vitamin D production Ca Ca2+2+ deficiency deficiency

Photoaging is degeneration in proportion to UV Photoaging is degeneration in proportion to UV exposure -- skin spots, skin cancer, wrinklingexposure -- skin spots, skin cancer, wrinkling

4141

Aging of Skeletal SystemAging of Skeletal System Osteopenia is loss of bone massOsteopenia is loss of bone mass

after 30, osteoblasts less active than osteoclastsafter 30, osteoblasts less active than osteoclasts after 40, women loose 8% per decade; men 3%after 40, women loose 8% per decade; men 3% brittle bones fracture and heal slowly due to brittle bones fracture and heal slowly due to protein protein

synthesissynthesis

Joint diseasesJoint diseases synovial fluid less abundant and articular cartilage thinner or synovial fluid less abundant and articular cartilage thinner or

absent -- friction causes pain absent -- friction causes pain osteoarthritis is common cause of physical disabilityosteoarthritis is common cause of physical disability

breathing difficult due to calcification of sternocostal jts.breathing difficult due to calcification of sternocostal jts. but herniated discs less common (less nucleus pulposus)but herniated discs less common (less nucleus pulposus)

4242

Aging of Muscular SystemAging of Muscular System

Muscular atrophy causes replacement of lean Muscular atrophy causes replacement of lean body mass (muscle) with fatbody mass (muscle) with fat by 80, we have half as much strength and enduranceby 80, we have half as much strength and endurance

fast-twitch fibers exhibit earliest and most severe atrophyfast-twitch fibers exhibit earliest and most severe atrophy

Reasons for loss of strengthReasons for loss of strength fibers have fewer myofibrils, smaller mitochondria, less fibers have fewer myofibrils, smaller mitochondria, less

enzymes, glycogen and myoglobinenzymes, glycogen and myoglobin fewer motor neurons in spinal cord with less efficient fewer motor neurons in spinal cord with less efficient

synaptic transmission of acetylcholinesynaptic transmission of acetylcholine sympathetic nervous system is less efficient so less sympathetic nervous system is less efficient so less

efficient blood flow to muscles causes fatigueefficient blood flow to muscles causes fatigue

4343

Aging of Nervous SystemAging of Nervous System Cerebral and neuronal atrophyCerebral and neuronal atrophy

from age 35 on, 100,000 brain cells die every dayfrom age 35 on, 100,000 brain cells die every day brain weight 50% less by age 75brain weight 50% less by age 75 cortex thinner, gyri narrower, fewer synapses and cortex thinner, gyri narrower, fewer synapses and

neuroglia, less neurotransmitter and receptorsneuroglia, less neurotransmitter and receptors degeneration of myelin slows down signal degeneration of myelin slows down signal neurons contain less ER and Golgi as their metabolism neurons contain less ER and Golgi as their metabolism

slows slows accumulate more lipofuscin pigment, neurofibrillary tangles accumulate more lipofuscin pigment, neurofibrillary tangles extracellular protein plaques accumulateextracellular protein plaques accumulate

Motor coordination, intellectual function and short-Motor coordination, intellectual function and short-term memory suffer the mostterm memory suffer the most

Autonomic nervous system is less efficient at Autonomic nervous system is less efficient at regulating body temperature and BPregulating body temperature and BP

4444

Aging of the Sense OrgansAging of the Sense Organs VisionVision

loss of flexibility of lenses (presbyopia)loss of flexibility of lenses (presbyopia) cataracts or cloudiness of lensescataracts or cloudiness of lenses night vision is impaired due to fewer receptors, vitreous night vision is impaired due to fewer receptors, vitreous

body less transparent, pupil dilators atrophy and body less transparent, pupil dilators atrophy and enzymatic reactions become slowerenzymatic reactions become slower

glaucoma risks increaseglaucoma risks increase

HearingHearing tympanic membrane and ossicle joints stiffentympanic membrane and ossicle joints stiffen hair cells and auditory nerve fibers diehair cells and auditory nerve fibers die death of receptor cells result in dizzinessdeath of receptor cells result in dizziness

Taste and smell is blunted as receptors declineTaste and smell is blunted as receptors decline

4545

Aging of Endocrine SystemAging of Endocrine System Degenerates less than any other systemDegenerates less than any other system

only reproductive, growth and thyroid hormones decline only reproductive, growth and thyroid hormones decline steadily after adolescencesteadily after adolescence

other hormones secreted at fairly stable rateother hormones secreted at fairly stable rate target cell sensitivity may declinetarget cell sensitivity may decline

Pituitary gland is less sensitive to negative Pituitary gland is less sensitive to negative feedback inhibition by adrenal glucocorticoidsfeedback inhibition by adrenal glucocorticoids response to stress is prolongedresponse to stress is prolonged

Type II diabetes is more common Type II diabetes is more common more body fat more body fat insulin sensitivity of other cells insulin sensitivity of other cells

target cells have fewer insulin receptorstarget cells have fewer insulin receptors

4646

Aging of Circulatory SystemAging of Circulatory System

Anemia may result from nutrition, lack of Anemia may result from nutrition, lack of exercise, changes in erythropoiesis, lack of exercise, changes in erythropoiesis, lack of intrinsic factor intrinsic factor vitamin B12 absorption vitamin B12 absorption

Coronary atherosclerosis leads to angina, Coronary atherosclerosis leads to angina, infarction, arrhythmia and heart blockinfarction, arrhythmia and heart block heart walls thinner, stroke volume and output declinesheart walls thinner, stroke volume and output declines degeneration of nodes and conduction systemdegeneration of nodes and conduction system

Atherosclerosis of other vessels increases BPAtherosclerosis of other vessels increases BP vessels stiffen and can not expand as effectivelyvessels stiffen and can not expand as effectively

Varicose veins due to weaker valvesVaricose veins due to weaker valves

4747

Aging of Immune SystemAging of Immune System

Amounts of lymphatic tissue and red bone Amounts of lymphatic tissue and red bone marrow declinemarrow decline fewer hemopoietic stem cells, disease-fighting fewer hemopoietic stem cells, disease-fighting

leukocytes and antigen-presenting cells leukocytes and antigen-presenting cells

Lymphocytes fail to matureLymphocytes fail to mature Both types of immune responses are less Both types of immune responses are less

efficientefficient less protection from cancer and infectious less protection from cancer and infectious

diseasedisease

4848

Aging of Respiratory SystemAging of Respiratory System Declining pulmonary ventilationDeclining pulmonary ventilation

costal cartilages less flexiblecostal cartilages less flexible lungs have less elastic tissue and fewer alveolilungs have less elastic tissue and fewer alveoli

Elderly less able to clear lungs of irritants and Elderly less able to clear lungs of irritants and pathogenspathogens more susceptible to respiratory infectionmore susceptible to respiratory infection

Chronic obstructive pulmonary diseases Chronic obstructive pulmonary diseases (emphysema and chronic bronchitis)(emphysema and chronic bronchitis) effects of a lifetime of degenerative changeeffects of a lifetime of degenerative change contribute to hypoxemia and hypoxic degeneration of contribute to hypoxemia and hypoxic degeneration of

other organ systemsother organ systems

4949

Aging of Urinary SystemAging of Urinary System Renal atrophy (40% smaller by age 90)Renal atrophy (40% smaller by age 90)

loss of nephrons and atherosclerotic glomeruliloss of nephrons and atherosclerotic glomeruli filtration rate decreases leaving little reserve capacityfiltration rate decreases leaving little reserve capacity

can not clear drugs as rapidlycan not clear drugs as rapidly

Fluid balanceFluid balance less responsive to antidiuretic hormone and sense of less responsive to antidiuretic hormone and sense of

thirst is sharply reduced (dehydration is common)thirst is sharply reduced (dehydration is common)

Voiding and Bladder controlVoiding and Bladder control 80% of men with benign prostatic hyperplasia80% of men with benign prostatic hyperplasia

urine retention aggravating failure of nephronsurine retention aggravating failure of nephrons

female incontinence due to weakened sphinctersfemale incontinence due to weakened sphincters

5050

Aging of Digestive SystemAging of Digestive System

Dental health affected by reduced salivaDental health affected by reduced saliva teeth more prone to caries and swallowing difficultiesteeth more prone to caries and swallowing difficulties

Gastric mucosa atrophies and secretes less acid Gastric mucosa atrophies and secretes less acid and intrinsic factorand intrinsic factor absorption of Caabsorption of Ca2+2+, iron, zinc and folic acid reduced, iron, zinc and folic acid reduced sphincters weaken resulting in more heartburnsphincters weaken resulting in more heartburn

Intestinal motility decreased due to weaker Intestinal motility decreased due to weaker muscle tone, less fiber, water and exercisemuscle tone, less fiber, water and exercise

Reduced food intake due to loss of appetite and Reduced food intake due to loss of appetite and mobility risks malnutritionmobility risks malnutrition

5151

Aging of Reproductive SystemAging of Reproductive System

MaleMale gradual decline in testosterone secretion, sperm count and gradual decline in testosterone secretion, sperm count and

libidolibido fertile into old age but impotence may occur due to fertile into old age but impotence may occur due to

atherosclerosis, hypertension, or medication atherosclerosis, hypertension, or medication

FemaleFemale more abrupt, rapid changes due to menopausemore abrupt, rapid changes due to menopause ovarian follicles used up, gametogenesis ceases and ovaries ovarian follicles used up, gametogenesis ceases and ovaries

cease production of sex steroidscease production of sex steroids vaginal dryness, genital atrophy, and reduced libidovaginal dryness, genital atrophy, and reduced libido

elevated risk of osteoporosis and atherosclerosiselevated risk of osteoporosis and atherosclerosis

5252

Exercise and SenescenceExercise and Senescence

Good nutrition and exercise are best ways to slow Good nutrition and exercise are best ways to slow agingaging exercise improves quality of life (providing endurance, exercise improves quality of life (providing endurance,

strength and joint mobility)strength and joint mobility) 90 year old can increase muscle strength threefold in 6 90 year old can increase muscle strength threefold in 6

months with 40 minutes of isometric exercise/weekmonths with 40 minutes of isometric exercise/week

Resistance exercise reduces bone fracturesResistance exercise reduces bone fractures Endurance exercises reduce body fat, and Endurance exercises reduce body fat, and

increase cardiac output and oxygen uptakeincrease cardiac output and oxygen uptake 3 to 5 twenty to sixty minute periods of exercise where 3 to 5 twenty to sixty minute periods of exercise where

raise heart rate 60-90% of maximum (220-age)raise heart rate 60-90% of maximum (220-age)

5353

Theories of SenescenceTheories of Senescence

Limit to number of times cells can replicateLimit to number of times cells can replicate Failure of polymerase to replicate terminal genes of DNA on Failure of polymerase to replicate terminal genes of DNA on

older chromosomes due to shortness of telomere (noncoding older chromosomes due to shortness of telomere (noncoding nucleotides at tip of chromosome)nucleotides at tip of chromosome)

Collagen molecules become cross-linked (less soluble and Collagen molecules become cross-linked (less soluble and more stiff)more stiff)

Proteins become abnormal due to improper folding or links to Proteins become abnormal due to improper folding or links to other moieties that attach to themother moieties that attach to them

Free radicals damage macromolecules (due to lack of Free radicals damage macromolecules (due to lack of antioxidants)antioxidants)

Lymphocytes mount an attack against own tissuesLymphocytes mount an attack against own tissues

5454

ProgeriaProgeria

Genetic disorder showing accelerated aging.Genetic disorder showing accelerated aging.