mod 13 - urinary system

anatomy of the urinary system

2 kidneys
2 ureters
1 urinary bladder
1 urethra

structure: ureter

Tube-like structure composed of transitional epithelium allows the ureter to stretch as urine is passed through.

function: ureter

- Move urine from the kidneys to the urinary bladder.
- The urine is moved to the bladder by peristalsis.

urethra

continuation of the neck of the bladder
- carries urine from bladder to external environment
- runs through pelvic canal

anatomy: female urethra

- Shorter and straighter

- Opens on floor (ventral portion) of vestibule of the vulva

- Lined with transitional epithelium which allows it to expand

anatomy: male urethra

- Longer and curved

- Runs along the ventral aspect of the penis

- Lined with transitional epithelium which allows it to expand

function: female urethra

Strictly a urinary function, Carries only urine

function: male urethra

- Has both urinary and reproductive functions
- Carries urine or semen

gross anatomy of kidneys

- fibrous connective tissue capsule
- hilus, renal pelvis, renal cortex, renal medulla, calyx

hilus

indented on medial side (ureters, nerves, blood and lymph vessels enter and leave)

renal pelvis

funnel-shaped area inside hilus

function: kidneys

production of urine to facilitate elimination of metabolic waste materials
- maintenance of homeostasis

kidneys -> maintenance of homeostasis through:

- Blood filtration, reabsorption, secretion

- Fluid balance regulation

- Acid-base balance regulation

- Hormone Production -> Erythropoietin

- Blood pressure regulation -> Renin

nephron

smallest functional unit that can carry out its basic function

what is the nephron composed of?

- renal corpuscle
- proximal convoluted tubule
- distal convoluted tubule
- loop of henle

where is the renal corpuscle located?

renal cortex

what is the glomerulus surrounded by?

bowman's capsule

what filters blood in the first stage if urine production?

glomerulus

what supplies blood to the kidney?

renal artery

urinary system: reabsorption

Useful substances leave tubules of nephron. "Recycled" back into the blood stream via the peritubular capillaries.

what substances are "recycled" back into the blood stream?

sodium, potassium, calcium, magnesium, glucose, amino acids, chloride, bicarbonate, and water

urinary system: secretion

- occurs in DCT

- waste products eliminated by secretion: hydrogen, potassium, ammonia

- Some medications also eliminated by secretion

Urine Volume Regulation

Urine volume is determined by amount of water contained in tubular filtrate when it reaches the renal pelvis

what controls urine volume regulation?

- Controlled by actions of Aldosterone and ADH

- Aldosterone – (Mineralocorticoid-Adrenal cortex)

Increases reabsorption of sodium and water

- ADH (Brain) – Regulates urine volume. Acts on DCT and collecting ducts to promote water reabsorption

aldosterone

increases reabsorption of sodium and water

ADH

regulated urine volume. acts on DCT and collecting ducts to promote water reabsorption

regulation of blood pressure

kidneys help maintain homeostasis by their role in regulating blood pressure

Renin-Angiotensin-Aldosterone System (RAAS)

responds when blood pressure falls

renin

is an enzyme produced by the kidney. aka angiotensinogenase

results renin

Increased amounts of sodium and water reabsorbed back into bloodstream, causing an increase in blood volume

as blood volume increases __________

blood pressure increases

What is the renal threshold for glucose?

there is a limit to the amount of glucose that can be reabsorbed

if blood glucose gets too high _________

the amount of glucose filtered through the glomerulus exceeds the amount that can be reabsorbed. the excess is lost in urine

urinary bladder

stores urine as it is produced

anatomy: urinary blader

transitional epithelium stretches as bladder fills with urine

detrusor muscle

contracts to expel urine

circular sphincter muscles around neck of bladder

provides voluntary control over urination process

urination is also known as

micturition or uresis

what are the 3 prices of micturition?

1. Urine accumulation -> Stretch receptors are activated
2. Muscle contraction -> Smooth muscle in bladder wall contracts
3. Sphincter muscle control -> Sphincter muscle is under voluntary control.

Which part of the Nephron is responsible for the first step in urine production?

renal corpuscle