Chapter 24- Urinary System Flashcards
Functions of the Urinary System
Maintain chemical consistency of blood
Filter fluid from blood
Send toxins, metabolic wastes, and excess water from body
Rid waste products like urea, uric acid, and creatinine
Mechanisms of Urine Production
Filtration
Reabsorption
Secretion
Filtration
Non-specific, filters all small molecules
Occurs in renal corpuscle
Filtrate leaves capillaries and enters urinary system
Reabsorption
Most nutrients, water, and ions are reclaimed from filtrate in tubules
Secretion
Active process of removing undesirable molecules from blood
Pushes substance from blood to tubules
Hilus of Kidney
Concave surface where renal blood vessels, nerves, and ureter meet kidney
Internal kidney anatomy
Cortex- Portion distal to renal blood vessels, contains nephrons
Medulla- Passage for urine toward ureter, internal, contains pyramids
Uriniferous tubule
Functional unit containing nephron and collecting duct
Collecting duct
Concentrates and stores urine
Connects to medullary pyramids
Nephron
Site of urine production
Contains Renal Corpuscle and Tubular Segments
Renal corpuscle
Site of filtration
Contain glomerulus (blood vessels) and glomerular (bowman’s) capsule
Glomerulus
Fenestrated capillaries that serve as the site of filtration
Blood filtrate leaves the circulatory system and into urinary system
Filtration driven by higher blood pressure in afferent than efferent blood vessels
Blood Filter Components
Fenestration of capillaries
Feet-like projections on podocytes
Glomerular (Bowman’s) Capsule
Epithelial sac surrounding glomerulus that receives filtrate
Parietal layer- Wall of capsule, simple squamous epithelium
Visceral layer- Covers blood vessels, podocytes that assist in filtration
Section of the Nephron Tubule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Drains into collecting duct
Functions of Nephron Tubule
Surrounded by a secondary capillary bed (peritubular capillaries) from efferent arterioles
Site of reabsorption and secretion
Juxtaglomerular Apparatus
Junction of distal convoluted tubule with afferent and efferent arterioles
Contain juxtaglomerular cells that detect stretch and secrete renin
Macula densa is chemoreceptor that controls renin
Renin
Hormone secreted by kidney structures that lead to the increase of water uptake and blood pressure
Types of nephrons
Cortical- 85%; stay mostly in cortex
Juxtamedullary- 15%, have vasa recta and dive deeper into medulla, produce concentrated urine
Path of Urine formation
Glomerulus
Renal tubules
Collecting duct
Pyramids of medulla
Minor calyx
Major calyx
Renal pelvis
Ureter
Urinary bladder
Urethra
Ureters
Transport urine to urinary bladder
Layers-
Mucosa made of transitional epithelium
Muscularis-
Inner longitudinal layer
Outer circular layer
Adventitia- Retroperitoneal connective tissue lining
Urinary bladder
Collapsible muscular sac that stores and expels urine
Detrusor muscle- Contracts to expel urine
Urethra
Connection from urinary bladder to outside of body
Female- 3-4cm
Males- 20+ cm
Epithelial lining-
Transitional near bladder
Stratified and pseudostratified columnar
Stratified squamous
Urethral sphincters
Inner- Involuntary smooth muscle
External- Skeletal muscle
Portions of male urethra
Prostatic- Passes through prostate
Membranous- Passes through urogenital diaphragm
Spongy- Passes through penis
Micturition
Urination
Nervous control of Urination
Visceral afferent detect stretch
Control center in pons
Sympathetic neurons are inhibited
Parasympathetic neurson contract detrusor and relax internal urethral sphincter
Somatic motor neurons relax external urethral sphincter
