Upload
isabel-bruce
View
214
Download
1
Embed Size (px)
Citation preview
11
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
99
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)
1414
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
1616
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
2222
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
2323
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
2828
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
2929
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.