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Reproduction Replacement and Repair (Hormonal Control (Hormones from…
Reproduction Replacement and Repair
Mitosis
Cellular reproduction is the process of making a new cell
Two kinds if cellular reproduction: sexual and asexual
Asexual cellular reproduction: when cells make an identical copy of themselves with the involvement of another cell
Most cells can reproduce themselves asexually (animal, plant, or bacteria).
Growth is accomplished through mitosis
Needed for repair and regeneration of tissues
Serves many purposes
Anytime the cells need to be replaced, it uses mitosis
Repair and regeneration of damaged tissue
Growth such as lengthening of a bone, or increase the muscle mass
Sexual reproduction
Needed for perpetuation of species
Requires assistance of another individual to produce offspring that are not identical to themselves
Involves union of cell from one organism with cell from another organism of same species to form unique new organism
Gametes produced by meiosis because daughter cells produced at end or meiosis have half as many chromosomes as original
The Human Cycle
Mitosis and meiosis are absolutely necessary parts of the human life cycle, needed for cell replacement, repair, and production of new organisms.
Eggs and sperm, with only half as many chromosomes as other cells, are produced by meiosis in specialized organs known as gonads
During sexual reproduction, gametes unite and combine their genetic material; the union is called fertilization
Zygote has 46 chromosomes; zygote reproduces millions of time via mitosis and develops within female to change from embryo to fetus.
Female Anatomy
Primary genitalia are ovaries
secondary genitalia are Fallopian tubes, uterus, vagina, and external genitalia called vulva.
Ovaries are paired structures, about 3 cm long, in peritoneal cavity
There is one ovary on either side of uterus
Several ligaments suspend or anchor each ovary
Mesovarium suspends ovary
Suspensory ligament attaches ovary to lateral pelvic wall
Ovarian ligament anchors ovary to uterine wall
The ovary
Covered by fibrous capsule called tunica albuginea made of cuboidal epithelium
Interior divided into cortex, which contains eggs and medulla, which contains blood vessels, nerves, and lymphatic tissue surrounded by loose connective tissue
Anatomy of cortex is relatively compliance and will be described during discussion of physiology
The uterine tubes
Also called oviducts or Fallopian tubes
Are passageways for eggs to get to uterus
Each tube begins as large funnel, infundibulum, surrounded by ciliated projections called fimbria
Infundibulum leads to widened area, ampulla, followed by a long, narrower portion known as isthmus
Uterine tubes are connected to superior portion of uterus
Constructed of sheets of smooth muscles lined with highly folded, ciliated, simple columnar epithelium
Uterus
Endometrium is highly vascular
Blood supplied by uterine artery, which branches from internal iliac arteries on each side
Uterine arteries split into actuate arteries, supplying myometrium, and radial arteries, which supply blood to endometrium
Straight radial arteries supply functional layer, decaying and regenerating every month as part of menstrual cycle, and undergoing spasms which contribute to shedding of endometrium each month
Blood returns to circulation via network of Venus sinuses
Consists of 3 layers
Perimetriem: outermost layer, also called visceral peritoneum
Myometrium: consists of smooth muscle layer
Endometrium: inner lining is mucosa layer of columnar epithelium and secretory cells with two divisions
The vagina
Tube, approximately 10 cm long, running from uterus to outside body
Also called birth canal, since another function is to allow movement of body out of uterus during childbirth
The external genital
Collectively known as vulva and is complex and important part of reproduction
The vulva is surrounded by to prominence called labia majora, rounded fat deposits that meet and protect rest of external genitalia
Labia majora meet anterior to form Mons pubis, covered by pubic hair
The perineum is the area between the vagina and the rectum
Hormonal Control
Hormones from hypothalamus, pituitary, and ovary control female cycle
Hormone levels generally by negative feedback look
Hormones often released as part of hierarchy, with hypothalamus releasing hormone that controls pituitary, which then releases hormone that controls another organ
Four hormones control menstrual cycle: estrogen and progesterone from ovary, and lutenizing hormone (LH) and follicle stimulation hormone (FSH) from pituitary
FSH initiates development of primary follicles
During follicular stage, estrogen levels continue to rise as more and more is secreted by developing follicle, stimulating proliferation of uterine lining
Estrogen exerts positive influence on hypothalamus, increase secretion of GnRH, thus increase LH and FSH
Positive feedback loop continues raising hormone levels until ovulation occurs, when feedback loop reverses itself
Once ovulation occurs, feedback loop reverses itself
Corpus luteum begins to secrete progesterone, as well as a little estrogen
Estrogen, under influence of progesterone, exerts negative feedback on hypothalamus and pituitary, decreases GnRH, LH and secretion
Male Anatomy
Like female has gonads, the male has gonads
Testes: primary genitalia, producing male gamete, sperm
Unlike female, primary male genitalia is external
Secondary genitalia: Penis, epidiymis, vas deferns, urethra, and several assessory glands including prostate gland, seminal vesicles, and bulbourethral glands
Testes
Paired organs suspended in sac called scrotum, hanging on either side of penis
During fetal development, testes formed in abdomen; in last 3 months of development, migrate to normal position in scrotum
Each testis is surrounded by serous membrane, called tunica vaginalis, originating peritoneum
The penis
Sperm delivery organ that transfers sperm from male to female
Attached portion called root, while freely moving part called shaft of body
Glans penis (tip) covered by loose section of skin called foreskin, unless man has been circumcised
Internally penis contains urethra, a transport passage for both sperm and urine
Has 3 erectile bodies, tubes with sponge-like, network of blood sinuses
Epididymis
Several ducts in male reproduction system
epididymis is comma shapped duct on posterior and lateral part of testes
Made of pseudostratified ciliated epithelium and smooth muscle
The Vas Deferens
Short tube, only 45 cm long
Lined with ciliated pseudostratified epithelium, like epididymis, but has thick smooth muscle layer and is surrounded by connective tissue layer called adventitia
Posterior to bladder, joins seminal vesicle to form ejaculatory duct, which then passes through prostate gland and empties into urethra
Between scrotum and inguinal canal, it runs through a tube with blood vessels and nerves, collectively called spermatic cord
Three accessory glands in male reproductive system
Seminal vesicles: highly coiled, posterior to bladder, made of pseudostratified epithelium, smooth muscle, and connective tissue
Prostate gland: chestnut-sized gland surrounding urethra just inferior to bladder made up of dense mass of connective tissue and smooth muscle with embedded glands
Bulbourethral glands: pea sized glands inferior to prostate
Benign Prostatic Hyperplasia (BPH)
Non-cancerous enlargement of prostate
Symptoms: enlarged prostate impinges upon urethra, causing
Weak urine stream
Incomplete voiding
Urinary frequency
Night time urination
Urinary urgency
Diagnosis
Weak urine stream
Incomplete voiding
Urinary frequency
Night time urination
Urinary urgency
Treatment
Drug treatments: decrease testosterone and shrink prostate; relax smooth muscle in prostate, improving urine stream
Surgical treatments: minimally invasive laser or microwave ablation. placement of stent in urethra, removal of part or all of prostate
Prostate Cancer
Most common non-skin cancer affecting American men
32,000 men die each year from prostate cancer
Prostate specific antigen (PSA) blood test can be used to screen for it
Prostate cancer screening should begin at age 50 (or earlier if family history)