HS 130 Anatomy & Physiology IIUnit 9 Seminar

Chapters 20 & 21Reproduction,

Growth and Development

Male Reproductive SystemMale Reproductive System

• Structural plan Reproductive organs are classified as

essential or accessory Essential organs of reproduction are the

gonads (testes in males), which produce sex cells called sperm

TestesTestes

• Testes: the gonads of men Structure and location

Testes in scrotum—lower temperature Covered by tunica albuginea, which

divides testis into lobules containing seminiferous tubules

Interstitial cells produce testosterone

What is the importance of the lower temperature of the scrotum?

Tubules of the Testis and Epididymis

the testicle is the darker sphere in the center

Spermatozoa

Spermatogenesis

What are the steps in the process of

spermatogenesis?

Female Reproductive SystemFemale Reproductive System

How does the location of the female gonads differ from the location of the male gonads?

• Microscopic structure Ovarian follicles—contain oocyte, an

immature sex cell (about 1 million at birth) Primary follicles—are covered with

granulosa cells (about 400,000 at puberty) Secondary follicles have a hollow chamber

called the antrum Corpus luteum forms after ovulation from

ruptured follicle

OvariesOvaries

OvariesOvaries

What is the role of the corpus luteum if fertilization occurs?

OvariesOvaries

Menstrual CycleMenstrual Cycle

Menstrual CycleMenstrual Cycle

• Male organs Designed to produce, store, and introduce mature sperm into the female reproductive tract

• Female organsDesigned to produce ova, receive the sperm, permit fertilization, facilitate fetal development and birth, and perform lactation

Summary of Male and Female Reproductive Systems

Summary of Male and Female Reproductive Systems

Prenatal PeriodPrenatal Period

• Prenatal period begins at conception and continues until birth

• Science of fetal growth and development is called embryology

Approximately how long does pregnancy last? Why is prenatal care so important?

Fertilization and ImplantationFertilization and Implantation•Fertilization is a specific biological event•occurs when the male and female sex cells fuse•after union between a sperm cell and the ovum has occurred, the cycle of life begins. •scanning electron micrograph shows spermatozoa attaching themselves to the surface of an ovum•only one will penetrate and fertilize the ovum.

• After three days of cell division, the zygote has developed into a solid cell mass called a morula

• Continued cell division of the morula produces a hollow ball of cells called a blastocyst

• The blastocyst implants in the uterine wall about 10 days after fertilization

• The blastocyst forms the amniotic cavity and chorion of the placenta

Implantation and Early DevelopmentImplantation and Early Development

How does the embryo receive nutrients before the placenta is functional?

Primary Germ LayersPrimary Germ Layers

The PlacentaThe Placenta

What are the functions of the placenta?

Birth DefectsBirth Defects

• Any structural or functional abnormality present at birth May be caused by genetic factors

Abnormal genes Abnormal number of chromosomes

May be caused by environmental factors Environmental factors are called

teratogens Especially harmful during the first

trimester

Postnatal PeriodPostnatal Period• Postnatal period begins at birth and lasts until

death• Divisions of postnatal period into isolated time

frames can be misleading• Life, growth, and development are continuous• Obvious changes in the physical appearance

occur between birth and maturity

InfancyInfancy• First four weeks is called neonatal period• Cardiovascular and respiratory changes

occur at birth Fetus is totally dependent on mother Newborn must immediately become

totally self-supporting

ChildhoodChildhood

• Extends from end of infancy to puberty

• Overall rate of growth remains rapid but decelerates

• Continuing development of motor and coordination skills

• Loss of deciduous or baby teeth and eruption of permanent teeth

AdolescenceAdolescence

• Average age range of adolescence varies from 13 to 19 years

• Period of rapid growth results in sexual maturity (adolescence)

• Appearance of secondary sex characteristics regulated by secretion of sex hormones

• Growth spurt typical of adolescence; begins in girls at age 10 and in boys at age 12

AdulthoodAdulthood

• Bones’ growth plates are fully closed in adult• Other structures such as the sinuses acquire

adult placement• Adulthood characterized by maintenance of

existing body tissues• Older adulthood

Every organ system of the body undergoes degenerative changes

Effects of AgingEffects of Aging• Skeletal system

Aging causes changes in the texture, calcification, and shape of bones

Bone spurs develop around joints Bones become porous and fracture easily

Effects of AgingEffects of Aging

• Integumentary system (skin) With age, skin sags and becomes

Thin Dry Wrinkled

Effects of AgingEffects of Aging

• Urinary system Nephron units decrease in number by 50%

between ages 30 and 75 Blood flow to kidney and ability to form

urine decrease

Effects of AgingEffects of Aging

• Respiratory system Calcification of costal cartilages makes it

difficult for rib cage to expand and contract normally

Wasting of respiratory muscles decreases respiratory efficiency

Respiratory membrane thickens; movement of oxygen from alveoli to blood is slowed

Effects of AgingEffects of Aging

• Cardiovascular system Degenerative heart and blood vessel

disease is among the most common and serious effects of aging

Hardening of arteries (arteriosclerosis) may result in rupture of blood vessels

Hypertension or high blood pressure is common in older adulthood

Effects of AgingEffects of Aging

• Special senses Eye lenses become hard and cannot

accommodate for near vision Decreased transmission of sound waves

caused by loss of elasticity of eardrum and fixing of the bony ear ossicles is common Some degree of hearing impairment is

universally present in the aged

Thanks for attending!

I’ll “see” everyone on the discussion boards!