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Kidney Functions, Location and External Anatomy
- Filters blood plasma of metabolic wastes, electrolyte/water homeostasis, and forming urine
- right kidney is slight lower (bc of liver)
- hilus- medial protion where blood vessels, nerves and ureter enter/exit the kidney
- fibrous capsule-protective layer that maintains kidney shape.
- pararenal fat, renal fascia, and perirenal fat capsule are external to capsule for protection
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Internal gross anatomy
- Seperated into cortex and medulla.
- Renal cortex- lighter colored outer portion, subjacent to capsule, contains glomerus, proximal and distal tubules. Has renal column that separates renal pyramid of medulla
- renal medulla- darker inner portion, contains renal pyramids, separated by renal cortex, the nephron loops and collecting (papillary) ducts.
- papillary ducts are internally pointed tips of pyramids projects into calyx. minor calyx (cup-shaped drain) combine to form major calyx, which combine to form renal pelvis.
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Kidneys: arteries and nerves
- Renal arteries are segemented and go through renal column, eventually pass glomerus in cortex and leave through veins
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mechanism of urine production
occurs in nephron, collecting duct concentrates urine
: filtrate, resembling tissue fluid, leave kidney capillaries and enter uriniferous tubule - Resorption: 99% of filtrate recovered, water, ions, nutrients return to circulation
- secretion: active process, undesirable molecule moved from tubule to uriniferous tubule.
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Nephron
- composed of renal corpuscle and tubular section (proximal convoluted tube, loop of Henle, and distal convoluted tube)
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Renal corpuscle
- filtration occurs here.
- Afferent/efferent glomerular arterioles transport blood for filtration. glomerulus a capillary plexus produces filtrate that excludes platelets and proteins. Hollowed glomerular capsule surround glomerulus and associated with proximal convoluted tube.
- Filtration occurs through visceral layer of capsule that has unusual branching epithelial cells, podocytes, which filters filtrate through filtration slits. Then basement membrane
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Tubular section of nephron
- proximal convoluted tube- in renal cortex, made of cuboidal epithelial cells with microvilli, active in resorption and secretion. Lots of transport proteins and activity
- loop of Henle- in medulla, continuous with proximal part, has thin segment that is permeable simple squamous epithelium, becomes ascending limb which is thick segment. Does reabsorption
- distal convoluted tubule- in cortex, simple cuboidal epithelium, selective secretion, some resorption, empties into collecting papillary duct
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Collecting ducts of kidney
- Urine from distal tubules goes to collecting ducts which go to papillary ducts which dump into minor calices.
- This is the part that is effected by ADH (antidiuretic hormone) which will concentrate the urine.
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blood vessles of uriniferous tubules
- Glomeruli: Only capillary bed that is fed and drained by arterioles, causing high pressure to send filtrate through.
- peritubular capillaries: runs along convoluted tube and specializes in absorption
- vasa recta: in deepest part of cortex and run along loop of Henle, for concentrating urine.
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Ureters
- ~25cm long continuations of renal pelvis that brings urine into bladder.
- Three layers:
- mucosa- transitional epithelium, lamina propia which is stretchy fibroelastic connective tissue.
- muscularis- 2/3 layers. Longitudinal inner and circular outer layer. third layer is distal part
- adventitia- typical connective tissue
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Urinary bladder
- inferior to peritoneal cavity. round when full (extends into abdomen). In men, prostate is directly inferior to bladder surrounding urethra.
- internal iliac arteries supply blood, hypongastric plexus supplies nerves.
- Trigone is internal triangle of ureters and urethra. This is where infections occur
- Three layers in bladder walls:
- mucosa with transitional layer, thick muscular layer (distensible detrusor muscle), and fibrous adventitia
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Urethra
- smooth muscle and inner mucosa that drains bladder.
- internal urethral sphincter: involuntary muscle, directly inferior to bladder, prevent urine from reverse entering bladder
- external urethral sphincter: voluntary muscle which control urination.
- in males: prostatic urethra, membraneous urethra, spongy urethra, and external urethral orifice, also exist
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Micturition (urination)
contration of detrusor muscle
disorders: incontinence, in elderly urge, stress, or overflow incontinence
Urinary retention
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Urinary tract infections, renal calculi, polycystic kidney disease, cancer
- UTI: mostly in sexually active females from external exposure, can travel to kidneys
- Renal calculi: kidney stones, crystalization of calcium, magnesium or uric acid. Pain occurs in passage of narrow parts of ureters.
- polycystic kidney disease: in children, cysts block urine in kidney leading to kidney failure and death.
- Cancer: bladder and kidney
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Sperm pathway
testes > duct of the epididymis > the ductus deferens > the ejaculatory duct > the urethra
- accessory sex glands that empty secretions into sex ducts during ejaculation are seminal vesicles, prostate and bulbourethral glands
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The scrotum (ball sac)
- contain the testes that are separated by a septum. External bc testes need temperature of ~3 cooler than body temperature
- dartos muscle- wrinkles scrotal skin to thicken layer when in cold environment
- cremaster muscle - contracts to elevate testes when cold
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testes: gross anatomy
- each surrounded by serous sac, tunica vaginalis. Deep to that is tunica albuginea which is fibrous capsule that compartmentalizes testicles into 250-300 lobules, seminiferous tubules.
- Each lobule converge posteriorly to form straight tubule to get sperm to rete testis. In turn this dumps into efferent tubules which enter the epididymis, attaced to back of testes
- pampiniform plexus are veins that surround testicular arteries to cool blood.
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Spermatogenic cells and sperm development
- spermatogenic cells are in seminiferous tubules. Process is triggered by FSH and testosterone
- spermatogonia (sperm stem cells) divide via mitosis. Type A daughter cells stay in basal lamina to maintain germline,Type B cells move toward lumen to become primary spermatocytes.
- After meiosis 1 cells become secondary spermatocytes after meiosis II they become spermatids.
- during spermiogenesis spermatids become sperm cell (spermatozoon) which a head (with helmit like acrosome), a midpiece (mitochondria), and tail (long flagellum)
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Sustentacular cells
- or Sertoli cells.
- divide seminiferous tubule into basal and adluminal compartments.
- for blood-testis barrier and tight junctions that allow for sperm passage.
- nourish spermatogenic cells, secrete testicular fluid (provides pressure), and adrogen-binding protein.
- also produce inhibin
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myoid and interstitial cells
- Myoid cells- are smooth muscle the surround seminiferous tubules that squeeze sperm and testicular fluid through tubules
- interstitial cells- Leydig cells. Produce male sex andrgens, testosterone. This is controlled by LH
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Epididymis
- "beside the testis" Sperm enter from rete testis and efferent ductules.
- comma-shaped on back of testis. highly coiled, stores sperm before ejaculation.
- stereocilia are not cilia but they absorb testicular fluid.
- Sperm become motile and acrosome functional
- From here sperm goes to ductus deferens
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Ductus deferens
- "carrying away", also vas deferens.
- Stores and transports sperm during ejaculation
- Distal end expands into ampulla of the ductus deferens, joins with seminal duct and becomes ejaculatory tract before emptying into prostatic urethra.
Wall has pesudostratified epithelium, and really thick muscularis, and outer adventitia
- tied off or cauterized during a vasectomy
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Spermatic cord and Urethra
- Largest part is ductus deferens, is fascia that also encloses testicular vessels and nerves.
- Place where inguinal hernias occur.
- Urethra has prostatic, membraneous and spongy urethra.
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Accessory glands of male reproductive organs
Seminal glands, prostate and bulbourethral glands
- produce bulk of semen
- Seminal vesicles (glands)-meets ductus deferens and ejaculatroy tract. secretes 60% of semen. secretes fructose and other nutrients, protaglandins (stimulate contraction of uterus), substance the inhibits immune response in females, substance that enhances sperm motility, enzymes the clot semen in vagina, florescent material.
- prostate- main, submucosal and mucosal glands, embedded in muscular fibromuscular stroma, which squeezes prostatic secretion into urethra. Secretes 1/3 of semen. Enhances motility, and liquifies semen. susceptible to tumors and STI, prostatitis.
- bulbourethral glands- pea-sized, inferior to prostate, produces mucus
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The penis
- consists of attached root, shaft (body), and tip glans, and the foreskin (or prepuce)
- has 3 erectile bodies, which make penis erect when filled with blood, arteries dilate and veins are squeezed shut.
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Male reproductive cancers
Testicular cancer: from rapidly dividing early spermatogenic cells. 95% treatable
prostate cancer: slow growing. second most common cause of cancer death in men. Tested through Prostate specific antigen concentration. Once metastasis occurs, nothing to do.
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Female reproductive organs
- ovaries
- accessory organs: uterine tubes, uterus, vagina
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The ovaries
- lateral to uterus.
- held in place by mesenteries, fed by ovarian arteries, innervated by both parts of autonomic nervous system.
- surrounded by thin but fibrous tunica albuginea, which is covered by germinal epithelium.
- Ovarian cortex houses developing gametes (oocytes) which are in follicles ("little bags") which enlarge as they mature. ovarian medullais loose conective tissue that houses blood vessels, nerves,and lymphatic vessels which enter through hilum.
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Ovarian cycle: part 1 follicular phase
- 6-12 primordial follicles each consisting of an oocyte and surrounding (support) cells, follicular cells start to grow.
- Oocyte grows (follicle 2), then follicular cells multiply forming stratified layer (becoming granulosa cells), oocyte develops glycoprotin layer, zona pellucida (which the sperm will penetrate).
- Granulosa cells divide forming connective tissue, theca folliculi. Theca cells influenced by LH secrete androgens which granulosa cell influenced by FSH turn into estrogen which stimulates other female sex organs.
- Clear liquid forms around granulosa cells forming atrum, around the now secondary (antral) follicle. outer granulosa cells become corona radiata. Mature follicle is called vesicular (Graffian) follicle, is ready to be ovulated. Only one follicle is ovulated
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Ovarian cycle parts 2 and 3: Ovulation and Luteal phase
- Ovulation: halfway point. large LH release, stimulates release of one oocyte into uterine tube surrounded by corona radiata
- Luteal phase: Second half. outer part of follicle still in ovary corpus luteum, secretes estrogen and progesterone which acts on mucosa of uterus preparing to implant embryo. But dies after 2 weeks becoming corpus albicans.
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Oogenesis
- Production of Ova
- in fetal period, oogonia, stem cells, give lifelong supply of oocytes which are arrested in meiosis I at birth. Primary oocytes. Until they are ovulated.
- Only with LH does primary oocytes undergo meiosis II and become secondary oocyte. But does not finish Meiosis II until sperm penetrates plasma membrane.
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uterine tubes (ovaducts or fallopian tubes)
- Opens into infundibulum margin is surrounded by ciliated projections, fimbriaeExpands into ampulla, where fertilization occurs. The medial third is the isthmus which ends in the uterus.
- Not directly connected to ovaries. Oocyte is released into peritoneal cavity.
- 90% of ectopic pregnancies occur in uterine tubes.
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The uterus
- upside down pear-shaped. located between rectum and bladder.
- major portion of the uterus is the body. the Fundus is superior to uterine entrance. The narrow part below the body is the isthmus which opens below into the cervix. This leads to the vagina and the vulva.
- Cervical canal connected to the body via internal os, and the vagina via the external os
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Supports of the uterus
- Mesometrium (to lateral pelvic walls), lateral cervical ligaments (from cervix and vagina to lateral pelvic walls), rounded ligaments of uterus (to anterior wall)
- mostly supported by muscles of pelvic floor.
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Uterine wall
- 3 layers.
- perimetrium- outer serous membrane, peritoneum.
- myometrium- bulky smooth muscle that contract during childbirth
- endometrium- mucosal inner lining. Where the embryo implants. has stratum functionalis which undergoes cyclic changes and in shed during menstruation and stratum basalis which created a new stratum functionalis every month.
- Acuate arteries in myometrium > radial arteries (endometrium) > straight arteries > spiral arteries (which regenerate every cycle)
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uterine cycle
- Menstrual phase ( days 1-5) - stratum functionalis is shed.
- proliferative phase (6-14) - functionalis rebuilds
- secretory phase (15-28)- endomedtrium plans for implantation of embryo
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female external genitalia
- vulva, mons pubis, labia majora, labia minora, vestibule, fourchette,
- clitoris- prepuce of the clitoris, paired corpora cavernosa,
- perineum- diamond shaped area, contains central and perinealbody
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mammary glands
- nipple, areola, suspensory ligaments of the breast
- lobules> lactiferous ducts> lactiferous sinuses
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pregnancy: Fertilization and implantation
- sperm travel to uterine tubes, acrosomal reaction is the release of digestive enzyme creating entrance in zona pellucida.
- After fertilization, cortical reaction removes sperm receptors.
- After day four: blastocyst enters uterus.
- day six: impantation occurs. trophoblast has two layers. outer syncytiotrophoblast degrades and implants in endometrium. Then lacunae open up and fill with maternal blood.
- day 10-12, first contract with nourishing maternal blood.
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Formation of placenta
- extraembyonic mesoderm (trophoblast inner surface), and the trophoblast form the chorion and chorionic villi which contact the lacunae with maternal blood. (nutrients and gas exchagne occur by the end of the first month)
- Extraembryonic mesoderm forms body stalk, the future umbilical cord.
- Placenta completed in month 2 and 3, Mother adjacent endometrium is decidua basalis and capularis which exit uterus after birth.
- Syncytiotrophoblast secretes substances that regulate pregnancy of and mother's body. T lmphocytes are shut off, progesterone and human chorionic gonadotropin (HCG) are secreted.
- placenta previa (placenta covers internal os) and placental abruption (placenta seperated from uterine wall)
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Childbirth
- Parturition about 266 days after fertilzation.
- Dilation (first) stage- regular contraction of uterus until cervix is fully dialated. 6-12 hours.
- expulsion (second) stage-full dilation until delivery. 20 minutes to 2 hours.
- placental (third) stage- delivery of placenta. 15 minutes later
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Reproductive system cancers in females
- Ovarian cancer- from germinal epithelium. hard to detect until metastasis
- endometrial cancer- endometrium of uterus. relatively early detection
- cervical cancer- from HPV, detected with Pap smear
- breast cancer- super dangerous once metastasis occurs. detection wit mammogram
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