Biology 322Human Anatomy I

Renal System

Organs of Renal System

Kidney

Located high in abdominal cavityPosterior to peritoneum

Liver pushes right kidney more inferiorlyMass ~ Size ~

Kidney

: External covering of dense irregular connective tissue

Outer solid region

Inner solid region 8 to 12 cone-shaped masses (apex toward hilus) called renal , separated by renal .

Hollow medial region, extensions = calyces Connects medially with ureter

Kidney:Each renal artery (direct branch of aorta) divides into lobar (segmental) arteries, which divide into interlobar arteries, then arcuate arteries (between cortex & medulla), which give off interlobular arteries into both cortex & medulla.

You learned these as part of the renal lab exercise. Be sure you also know them for lecture exams

In cortex, interlobular arteries send blood through afferent arterioles into groups of capillaries called glomeruli.

This is where filtration will occur to begin formation of urine

From a glomerulus, blood flows out an efferent arteriole to another set of capillaries called peritubular capillaries which surround the tubules where urine is forming.

Each renal artery divides into lobar arteries, interlobar arteries, arcuate arteries, interlobular arteries, afferent arterioles, glomeruli, efferent arterioles, peritubular capillaries

Blood then flows into interlobular veins orarcuate veins,interlobar veins, andlobar veins to reach the renal vein which carries it to the inferior vena cava.

Consists of a group of interconnected capillaries. As blood flows through these capillaries, plasma (the liquid part of blood) is filtered out and flows though a series oftubes to form urine.

This series of tubes is calleda nephron.

Let’s go back to the glomerulus:

Structure of Glomerulus

Capillary wall (simple squamous epithelium, fenestrated) plus podocytes plus basement membrane between them form the filtration membrane across which liquid is filtered from the blood to the glomerular capsule.

Each kidney contains ~ 1,000,000 nephronsPattern of nephrons creates pattern of cortex and medulla:

Cortex consists primarily of convoluted tubules which twist many directions.

Medulla consists primarily of loops of Henle & collecting ducts all oriented in the same direction

This fluid filtered out of the blood flows into the proximal convoluted tubule, through other parts of nephron, into collecting duct.

Recall that nephron is surrounded by peritubular capillaries for resabsorption of water and solutes

Urine passes from a collecting duct into a minor calyx, then a major calyx, then the pelvis of the kidney.

Urine leaving the pelvis enters the ureter, which carries it to the urinary bladder.

Ureters: Retroperitoneal.

Anterior to common iliac arteries & veins.

Deliver urine to posterolateral parts of urinary bladder.

Ureter:

Mucosa: Transitional epithelium Lamina Propria (loose C.T.)

Muscularis: Thick wall of smooth muscle

Adventitia: Dense irregular C.T.

Urinary Bladder:

In pelvis, posterior to pubic boneSuperior surface covered by peritoneum

Female: Anterior to uterus/vagina

Male: Anterior to rectumSuperior to prostate

Urinary Bladder:

Mucosa: Transitional epithelium Lamina propria

Muscularis: Thick smooth muscle (“detrusor”)

Adventitia (C.T.) covers most of bladder Serosa on its superior surface

Urinary Bladder:

Urinary Bladder:

Urinary Bladder:

Muscularis (detrusor muscle) andInternal Urethral Sphinter both smooth muscle; thus involuntary

Urine leaving bladder enters urethra

Urethra:

Adventitia: Dense irregular C.T.

Muscularis: Thick wall of smooth muscle

Mucosa: Epithelium varies from transitional near bladder to stratified squamous at end Male urethra much longer, has middle region of stratified columnar. Female urethra does not. Lamina Propria (loose C.T.)

External Urethral Sphincter

External UrethralMeatus

Tonight:

On yourself or another person, locate kidneys ureters bladder urethra