Urinary System - Study Guide

Urinary System- Study Guide Structures of Urinary System: ● Kidneys: filter blood and convert the filtrate into urine ● Ureters: urine is transported by the ureters from the kidneys to the urinary bladder ● Urinary bladder: an expandable, muscular sac that stores as much as 1 liter of urine ● Urethra: urine eliminated through urethra Functions: ● Elimination of metabolic wastes ● Regulation of ion levels ION= Elecrolytes * E.g., Na+, K+, Ca2+ ● Regulation of acid-base balance (Blood PH) * Alters levels of H+ and HCO3 ● Regulation of blood pressure ● Elimination of biologically active molecules * hormones, drugs Location of Kidneys the left kidney: in between the level of the T12 and L3 vertebrae the right kidney: about 2 centimeters inferior to the left kidney to accommodate the large size of the liver Concave medial border, hilum ● Where vessels, nerves, ureter connect to kidney Anterior Posterior 4 tissue layers that surround and support the kidneys ● Fibrous capsule: GIVES IT ITS SHAPE ○ Directly adhered to external surface of kidney ○ Dense irregular CT ○ Maintains kidney’s shape ○ Protects it from trauma ○ Prevents pathogen penetration ● Perinephric fat: CUSHION & SUPPORT ○ Adipose Connective Tissue external to fibrous capsule ○ Cushions and supports kidney ● Renal fascia: HELPS CONNECT KIDNEY TO WALL ○ External to perinephric fat ○ Dense irregular CT ○ Anchors kidney to ○ surrounding structures ● Paranephric fat: CUSHION ○ Outermost layer surrounding kidney ○ Adipose CT ○ Anchors kidney to surrounding structures Regions and components of kidney: Renal Cortex: outermost region of the kidney. Renal Columns: project into the medulla and subdivide it into renal pyramids.- Renal Pyramids: striped structures within the medulla. Medulla: inner portion of the kidney.Corticomedullary Junction: where the outer edge of the medulla meets the cortex. Renal Papilla: located at the narrow/inner part of the renal pyramids. Each funnel-shaped minor calyx is associated with a pyramid and merge into larger major calyx which then merges to form the renal pelvis which then drains into the collecting duct. The Autonomic innervation of the kidney ● ● Sympathetic nerves ○ extend from the T10-T12 segments of the spinal cord to the blood vessels of the kidney. ○ These nerves innervate the afferent and efferent arterioles, which are responsible for regulating blood flow in and out of the glomerulus ○ Decreases urine production Parasympathe4c nerves from CN X (Vagus) ○ Specific effects not known ○ extends to the juxtaglomerular apparatus, which is involved in regulating renal blood pressure and fluid balance ○ This sympathetic input plays a role in modulating renal vascular resistance and adjusting glomerular filtration rate based on physiological needs. "Sympathetic nerves originating from the T10-T12 segments of the spinal cord provide innervation to the blood vessels of the kidney, including the afferent and efferent arterioles, as well as the juxtaglomerular apparatus" Renal Corpuscle and its components ● ● The renal corpuscle is located in the renal cortex and consists of the glomerulus and the glomerular capsule. The glomerulus is a network of capillary loops where blood enters through the afferent arteriole and exits through the efferent arteriole. The glomerular capsule has two layers: ● ● a visceral layer that covers the glomerular capillaries directly, and an external parietal layer. Between the two layers of the glomerular capsule is a capsular space that receives filtrate. Components of a Renal Tubule Proximal convoluted tubule (PCT): ● First region of the renal tubule ● Composed of simple cuboidal epithelium with tall microvilli ● Microvilli increase reabsorption capacity Nephron loop: ● Begins at the sharp end of the PCT ● Includes a descending limb and ascending limb ● Portions classified as thick or thin based on epithelium lining (thick, thin, thin, thick) Distal convoluted tubule (DCT): ● Starts at the end of the nephron loop and extends to the collecting duct ● Made up of simple cuboidal epithelium ● Contains much shorter microvilli Types of nephrons and the functional difference between them The cortical nephrons are located with their corpuscles near the top edge of the cortex and have a short loop that barely touches the medulla. 85% of nephrons are cortical. The juxtamedullary nephrons corpuscle lies near where the renal medulla and renal cortex meet. Its loop extends deep into the renal medulla. These nephrons are important in establishing salt concentration gradient in ISF, which allows regulation of urine concentration by ADH. Collecting tubules & Collecting ducts ● ● ● ● Each kidney contains numerous collecting tubules and larger collecting ducts. Tubules and ducts project towards the renal papilla. Collecting ducts empty into papillary ducts within the renal papilla. Epithelial cells in tubules start as cuboidal-shaped and then transition to columnar shape in the collecting ducts. Functions of the two types of specialized epithelial cells found within collecting tubules and ducts principal cells: have cellular receptors to bind both aldosterone (released from the adrenal cortex) and antidiuretic hormone (released from the posterior pituitary) intercalated cells (types A and B): specialized epithelial cells that help regulate urine pH and blood pH