Anatomy II

kidney functions

excretion of waste products

regulation of:

• blood ionic composition

• blood pH

• blood volume

• blood osmolarity

• glucose levels

production of hormones:

• calcitriol (active form of vitamin D, regulates Ca homeostasis)

• erythropoietin

enzymatic blood pressure regulation by secreting renin

kidneys

retroperitoneal organs

located on posterior abdominal wall between T12 and L3

renal hilum on concave border

surrounded by 3 layers of tissue: renal capsule, adipose capsule, renal fascia

contains the adrenal (suprarenal) gland on the top

kidney tissue surrounding

renal capsule (dense irregular connective tissue), closest to kidney

adipose capsule

renal fascia (dense irregular connective tissue)

kidney internal structure

renal cortex is the outer layer

renal medullar is the inner portion making the renal pyramids, base pf pyramids face cortex

apex of pyramids, final papilla, points towards hilum

renal columns are areas of cortex between pyramids

renal lobe: pyramid and overlying cortex with half-columns on each side

renal calyces

minar calyx receives urine from papillary ducts of one renal papilla

each kidney has 8-18 minor and 2-3 major

renal pelvis is single large cavity within kidney connected to ureter

renal sinus: renal pelvis, calyces, renal blood vessels and nerves

renal blood supply

renal arteries are branches of abdominal aorta

divide into segmental, interlobar, arcuate, interlobular aa, afferent arterioles, glomerular, efferent arterioles, peritubular capillaries, vasa recta

renal veins are tributaries of inferior vena cava

divide into interlobular veins, arcuate veins, interlobar veins, renal vein

ureters

muscular ducts that carry urine from kidneys to urinary bladder

retroperitoneal

constrictions at:

• pelviureteric junction

• pelvic brim where it crosses iliac vessels

• ureterovesical junction

urinary bladder

hollow organ with strong muscular walls, characterized by distensibility

situated in pelvic cavity, posterior to the pubic symphysis. superior surface covered by peritoneum

when empty is tetrahedral in shape with:

• trigon (floor): ureteral openings and internal urethral orifice (internal urethral sphincter, more inferiorly external)

• apex points to pubic symphysis

3-layered wall: mucosa, muscular, adventitia, serosa

urinary bladder walls

mucosa (transitional epithelium, lamina propria, forms rugae

muscularis

adventitia (posterior and inferior aspects)

serosa (superior)

female urethra

ends in external urethral orifice

wall: mucosa and muscular (circular layer)

mucosa: transitional → stratified columnar/pseudostratified columnar → non-keratinized simple squamous

shorter than male

male urethra

longer, double passage (urine, semen)

prostatic; openings: ducts from prostrate, seminal vesicles and ductus (vas) deferens

membranous

spongy (penile); bulbourethral (Cowper’s) glands, urethral glands

micturition

discharge of the urine from the urinary bladder occurs as a combination of involuntary and voluntary muscle contraction

urinary system function

maintaining optimal blood quality

balancing:

• water vs electrolytes → pH balance

excretion:

• metabolic waste

• water

• electrolytes

• bioactive (drugs)

secretion:

• renin

• erythropoietin

conversion:

• Vit D → calcitriol

• glucogenesis

kidney structures

renal pyramids

• regions of urine collection and transport

renal papilla

• regions of renal pyramid apex and funnel

medulla

• contains renal pyramids

cortex

• contains renal filtration apparatus

renal columns

• extensions of the cortex into the medullary region

renal lobe

• renal pyramid + cortical vase + cortical sides

renal lobule

• multiple nephrons draining into a shared collecting duct and associated cortical tissue

nephrons

function units of kidney

each kidney contains 1.25 million nephrons

each nephron comprises a corpuscle

simple epithelial tubule consists of three regions

• proximal convoluted tubule

• loop of henle

• distal convoluted tubule

loop of henle

has four regions and is the loop into the medulla of the nephron

• proximal straight tubule

  • largely continuous with PCT

• thin descending limb

  • simple squamous epithelium

  • passive resorption of Na+ and Cl-

• thin ascending limb

  • simple cuboidal epithelium (no brush border/many mitochondria)

  • active resorption of electrolytes

  • active excretion of Na+

• thick ascending limb

renal corpuscle

glomerulus + bowman’s capsule

bowman’s capsule (visceral layer):

• podocytes with interdigitated pedicels

• podocyte basal laminae + endothelium = Glomerular Basement Membrane

bowman’s capsule (parietal layer)

• simple squamous epithelium → cuboidal at tubular pole

proximal convoluted tubule

comes directly after the corpuscle

histological features

• simple cuboidal epithelium

• central nuclei

• brush border - microvilli

functions

• reabsorption of 2/3 total water, all organic nutrients, all proteins and electrolytes

distal convoluted tubule

histological features

• simple cuboidal epithelium

• smaller cells

• no brush border (short microvilli)

functions

• reabsorption of electrolyes

• regulation of Na+ by adrenal glands

juxtaglomerular apparatus

maintains glomerular filtration rate

macula densa

• simple columnar epithelium

• densely packed

• apical nuclei

• NaCl sensor

juxtaglomerular cells

• tunica media of afferent arteriole

• modified smooth muscle cells

• round nuclei

• blood pressure sensor

lacis cells

• support cells

• contractile capacity

• physiological connection

collecting ducts kidney

histological features

• in cortex: simple cuboidal epithelium

• in medulla: simple columnar

functions:

• reabsorption of water if needed

• carrying filtrate to calyces

ureters

3 layers:

mucosal layer

• transitional epithelium

  • basal cells

  • cuboidal/low columnar cells

  • umbrella cells

    • large elliptical surface cells

    • sometimes binucleated

• laminate propria

muscular layer

• inner longitudinal

• outer/middle circular

• outer longitudinal

adventitial layer

• fibroeslastic connective tissue

urinary bladder hist

3 layers

mucosal layer:

• transitional epithelium

• laminate propria

• submucosa

muscular layer

• inner longitudinal

• middle circular

• outer longitudinal

adventitial layer

• upper bladder only covered by serous peritoneum

umbrella cells

unique thick apical membrane

• lipids assembled into plaque

• numerous tight junctions on lateral membranes

• provides protection from hypertonic urine

urethra hist

female: 3-5 cm

• transitional → stratified squamous

male:

1. prostatic urethra

   1. transitional epithelium

2. membranous urethra

   1. stratified/pseudostratified columnar epithelium

3. spongy urethra

   1. stratified/pseudostratified columnar epithelium

   2. stratified squamous distally

primary reproductive organs

gonads: testes and ovaries produce gametes (sperm and ova) and secrete sex hormones

primary sex characteristics are directly involved in reproduction of the species

accessory reproductive organs

ducts, glands and supporting structures

secondary sex characteristics are features not directly concerned with reproduction, such as voice quality, facial hair, and breast size

male reproductive organs

grouped by function:

gonads (testes)

ducts - epididymis, ductus deferent, ejaculatory ducts and urethra

accessory sex glands - seminal vesicles, prostate and bulbourethral glands

supporting structures - copulatory organ (penis, scrotum)

scrotum

cutaneous sack:

• internally divided by the scrotal septum into two sacks and externally by the scrotal raphe

musculature of the scrotum:

• dartos muscle (smooth muscle, wrinkles and relaxes the skin of the scrotum)

• cremaster muscle (skeletal muscle, elevates and lowers the testes)

testes

oval paired glands

produce sperm and hormones

testes are covered by several layers of connective tissue

connective tissue extends inwards and divide testis into lobules

lobules contain 2-3 seminiferous tubules (site of sperm production) → rete testis → efferent ducts → ductus epididymis

epididymis

located along the posterior border of each testis; head, body, tail

single highly coiled tube enveloped by smooth muscle cells

site of sperm maturation, storage; sperm is propelled into the ductus (vas) deferens

ductus (vas) deferens

continuation of the duct of epididymis, conveys sperm to the urethra

spermatic cord

supporting structure of the male reproductive system that ascends from the scrotum and consists of

• ductus deferens

• testicular artery

• veins (venous plexus)

• nerves and lymphatics

seminal vesicles

paired seminal vesicles lying posterior on the base of the urinary bladder and secrete alkaline fluid rich in fructose, clotting agents

duct of seminal vesicle unite with the ductus deferens and form ejaculatory duct which opens into the prostatic urethra

prostate

inferior to the urinary bladder

single accessory gland - prostate, surrounds prostatic part of the urethra

prostate produce slightly acidic secretion, citric acid, proteolytic enzymes (prostate specific antigen, amylase, protease)

enlargement of the prostate after the age of 45 common

bulbourethral glands

inferior to prostate

lateral to membranous urethra

alkaline secretions, mucus

semen

sperm (50-150 million per 1 mL) + seminal fluid (produced by seminal vesicles, prostate, bulbourethral glands); coagulates after ejaculation

penis

copulatory organ contains: body, glans, root

body has three cylindrical masses of tissue covered by tunica albuginea

• corpora cavernosa: two dorsolateral masses; comprised of erectile cavernous tissue

• corpus spongiosum: ventral mass: contains covernous erectile tissue and spongy (penile) urethra, expanded region — glans (prepuce)

root of penis is attached position consisting of:

• bulb - extended portion of the base of the corpus spongiosum

• crura - extended portions of the corpora cavernosa

remale reproductive organs

internal

• ovaries

• uterine (fallopian) tubes

• uterus

• vagina

external

• vulva

• mammary glands

ovaries

almond shaped glands, located on the lateral walls of the lesser pelvis

functions:

• production of gametes

• production of hormones (estrogen, progesterone, relaxin)

covered by:

• germinal epithelium (simple cuboidal/squamous)

• tunica albuginea (dense irregular connective tissue)

two regions:

• cortex (contains ovarian follicles)

• medulla (contains blood vessels, nerves and lymphatic vessels

uterine (fallopian) tubes

extend from the uterus, between the fold of broad ligaments and open near the ovaries; transport the secondary oocyte

divided into:

• infundibulum - ends in fimbriae

• ampulla - longest, widest portion, usual place of fertilization

• isthmus

uterus

thick-walled, pear shaped muscular organ, located in the lesser pelvis with its body on the top of urinary bladder and its neck (cervix) between the urinary bladder and rectum; projects anterosuperiorly

site of implantation, fetal development, menstrual flow

attached by “ligaments” including broad and round

divided into:

• fundus - superior to the isthmus of the uterine tube

• body (between the layers of broad ligament), uterine cavity

• cervix - cervical canal, internal and external os

vagina

fibromuscular canal between uterine cervix and the exterior of the body (vaginal orifice)

located posterior to the urethra and urinary bladder and anterior to rectum

receptacle for penis, menstrual flow, childbirth

vaginal fornix - recess around the cervix

hymen vascularized mucous membrane, partially closes the vaginal orifice

vulva

external genitals of the female:

• mons pubis - adipose tissue covered with the skin and pubic hair

• labia majora - two longitudinal folds of skin covered with pubic hair, contains adipose tissue and sweat and oil glands

• labia minora - skin folds, devoid of pubic hair and fat

• clitoris - cylindrical mass of erectile tissue and nerves

• vestibule - the region between the lava minora

vestibule

hymen

vaginal origice

external urethral orifice

ducts of the greater vestibular glands (bartholin’s)

bulb of vestibule - consists of two elongated erectile bodies deep tot he labia on either side of the vaginal orifice

perineum

external surface area located inferior to the pelvic diaphragm (formed by muscles)

osseous boundaries (pubic symphysis, ischial tuberosisties and coccyx)

transverse line joining the anterior ends of the ischial tuberosities divides perineum into two triangles: urogenital and anal

midpoint of the line joining ischial tuberosities is the central point of the perineum overlying the perineal body (fibromuscular mass)

mammary gland

suspensory ligaments firmly attach breast to the dermis and fascia

each lobule (glandular tissue) is drained into mammary ducts