Ch 24 Urinary System Learning Objectives & PPTs

Describe the functions of the urinary system

- water, electrolyte, and acid-base balance

- removal of nitrogenous wastes

- blood is filtered into filtrate, then concentrated into urine

Kidneys

pair of organs that form and concentrate urine

Ureters

transport urine from kidneys to urinary bladder

Urinary bladder

temporary storage reservoir for urine

Urethra

transports urine from urinary bladder out of the body

3 Regions of urethra in males

Prostatic; Immediate; Spongy

Prostatic urethra

passes through the prostate gland

Immediate urethra

runs through urogenital diaphragm to beginning of pelvis (7)

Spongey urethra

runs through penis; opens at external urethral orifice

Location of kidney

below liver and posterior to stomach; on posterior wall of abdominal cavity and protected by floating ribs; right kidney lower than left kidney

Kidney functions

regulate total water volume; regulate total ion and solute concentration; maintaining acid-base balance; producing hormones (erythropoietin and renin); activating vitamin D; carrying out gluconeogenesis

Kidney hilum

medial indentation, entry point for renal artery, nerves, exit renal vein, ureter

Layers of the kidney

1. renal fascia

2. perirenal fat capsule

3. fibrous capsule

renal fascia

outer layer of dense fibrous connective tissue that anchors the kidney to abdominal wall

perirenal fat capsule

fatty cushion inside renal fascia

fibrous capsule

capsule surrounding each individual kidney

3 main regions of kidney

1. renal cortex

2. renal medulla

3. renal pelvis

renal cortex

granular-appearing superficial region

renal medulla

inner portion of the kidney

parts of renal medulla

renal pyramids and renal columns

renal pyramids

triangular-shaped areas of tissue in the medulla of the kidney; contain corticomedullary junction and papillae

renal columns

extensions of cortex in between pyramids to divide them

Renal sinus

a set of tubes/opening that drain urine from the medulla

parts of renal sinus

1. minor calyx 2. major calyx 3. renal pelvis

renal pelvis

funnel-shaped reservoir that collects the urine from major calyx and passes it to the ureter

minor calyx

drains a renal pyramid

major calyx

drains urine from minor calyces

kidney stones

a hard mass formed in the kidneys, typically consisting of insoluble calcium compounds; caused by dehydration, diet or genetic factors

hydronephrosis

backup of urine from ureteral obstruction or other causes; can lead to death of kidney tissue

path of blood flow from aorta, to kidney, to nephron, and back to IVC

1. aorta

2. renal artery

3. segmental artery

4. interlobar artery

5. arcuate artery

6. interlobular artery

7. afferent arteriole

8. glomerulus

9. efferent arteriole

10. peritubular capillaries of convoluted tubules and vasa recta of nephron loop

11. interlobular vein

12. arcuate vein

13. interlobar vein

14. renal vein

nephron

structural and functional unit of the kidneys that form urine

2 parts of nephron

1. renal corpuscle

2. renal tubule

renal corpuscle

consists of a tuft of capillaries called glomerulus and glomerular capsule; fed by afferent arteriole

glomerulus

composed of fenestrated capillaries that allow a large amount of solute-rich fluid to pass from blood to glomerular capsule

glomerular capsule

cup-shaped hollow structure that surrounds glomerulus

layers of glomerular capsule

1. parietal- simple squamous epithelium (structural)

2. visceral- podocytes (filtration membrane)

renal tubule

microscopic tube in the kidney where urine is formed after filtration; made up of a single layer of epithelial cells

3 regions of renal tubule

proximal convoluted tubule, nephron loop, distal convoluted tubule

proximal convoluted tubule (PCT)

reabsorption/secretion

nephron loop

simple squamous cells; water reabsorption and urine concentration

distal convoluted tubule (DCT)

secretion

collection duct

collects urine from DCT of several nephrons and drains into renal pelvis

cortical nephrons

85% of nephrons; almost entirely in cortex and loops does not descend into medulla

juxtamedullary nephrons

long nephron loops invade medulla; important in production of more concentrated urine

micturition

act of passing urine

stretch receptors

found in bladder and detect when its full; trigger micturition reflex

actions of micturition

1. contraction of detrusor muscle (smooth)

2. relaxation of bladder neck and urethral sphincters (skeletal and smooth)

what controls detrusor muscle

parasympathetic nervous system

what controls internal sphincter

sympathetic nervous system

what controls external sphincter

Somatic nervous system (voluntary)

what initiates urine storage

sympathetic fiber via T11-L2 spinal nerves and somatic fibers via the pudendal nerve

somatic fibers via pudendal nerve

promotes internal and external urethral sphincters

sympathetic fibers via T11-L2 spinal nerves

inhibit detrusor contraction and activate internal sphincter contraction

urinary incontinence

caused by weakened pelvic floor muscles; normal in infants

urinary retention

inability to empty the bladder; common after general anesthesia or opioids; need catheter

how do opiods and anethesia block urination

1. decreasing sensation of bladder fullness (stretch receptors)

2. inhibition of parasympathetic fibers (detrusor contraction)

benign prostatic hyperplasia (BPH)

noncancerous enlargement of the prostate; located below bladder; caused by age; treat with ablation, alpha-blockers, Cialis/viagra