[LEC] LESSON 2: RENAL MORPHOLOGY AND FUNCTION Flashcards
-organ responsible for urine formation
Kidneys
-bean-shaped paired organs that represent 0.5% of the total body weight
Kidneys
-carries urine from the kidneys to the urinary bladder
Ureters
-Approximately 25cm in length
Ureters
-stores urine
Urinary Bladder
-shaped like a 3-sided pyramid
Urinary Bladder
-delivers urine for excretion
Urethra
—area of attachment through which the blood vessels and nerves pass into and out of the kidneys
*Hilus
—blood vessel through which blood enters the kidney
*Renal artery
—blood vessel through which blood leaves the kidney
*Renal vein
—outer layer of the kidney about 1.4cm thick which serves as the exclusive site for plasma filtration
*Renal cortex
—portions of the cortex that extend between renal pyramids
*Renal columns
—inner region that has a stringy macroscopic appearance-Contains the collecting ducts
Renal medulla
—any of the conical masses that project as renal papillae into the renal pelvis
•Renal pyramids/Malphigian pyramid
—overlying the cortex area
•Renal lobe
—cup-like divisions of the renal pelvis surrounding one or more renal papillae
•Calyces (major and minor)
—funnel-shaped structure that is formed at one end by the expanded upper portion of the ureter
•Pelvis
—functional unit of the kidney located mostly in the cortex Each kidney contains 1 to 1.5 million nephrons
•Nephron
TWO TYPES OF NEPHRON
- Cortical Nephrons
- Juxtamedullary Nephrons
-Comprise approximately 85% of the total number of nephrons
-Function for urine concentration
Cortical Nephrons
Juxtamedullary Nephrons
-Primarily located in the cortex and function for tubular reabsorption and secretion
-Have loops of Henle that extend into the medullary region
Juxtamedullary Nephrons
COMPONENTS OF A NEPHRON
I. Renal Corpuscle
II. Renal Tubules
III. Collecting Duct
-Tuft of capillaries within the Bowman’s capsule
Glomerulus
-Structure that surround the glomerulus
•Bowman’s capsule
-Has a bigger lumen and carries blood to the glomerulus
•Afferent arteriole
-Has a smaller lumen and carries blood from the glomerulus
•Efferent arteriole
-Has a convoluted portion and a straight portion which becomes the Loop of Henle once it reaches the medulla
•Proximal Convoluted Tubule (PCT)
-Thin Descending Segment-U-Shaped Segment
-Thin and Thick Ascending Segment
•Loop of Henle
-Composed of 2 to 3 loops and begins at the juxtaglomerular paratus with the macula densa
•Distal Convoluted Tubule (DCT)
-Serves as the site of final urine concentration
III. Collecting Duct
Renal Physiology
I. RENAL BLOOD FLOW
II. Glomerular Filtration
III. TUBULAR REABSORPTION
-Directly affects the kidney’s functional ability
-1,200 ml/minute
RENAL BLOOD FLOW
Renal Plasma Flow:
600-700 ml/min
-process that involves the filtration of blood which leads to the formation of the ultrafiltrate
Glomerular Filtration
-Coil of ~8 capillary lobes (capillary tuft)
-Non-selective filter of plasma substances with MW of <70,000 Da
Glomerulus
Factors affecting filtration
a.Filtration Barrier
b.Net Filtration Pressure
c.Feedback mechanism of RAAS
: increases permeability
Fenestrated endothelium
: provides further restriction of main size discriminant barrier to protein passage
Basement membrane
: afforded by negatively charged components provides additional restriction by repelling positively-charged molecules
Shield of Negativity
: with intertwining foot processes (podocytes) forms filtration slitss
Visceral epithelium
-Pressure that forces substances from the glomerular capillaries into the Bowman’s capsule
Net Filtration Pressure
-pressure in the glomerular capillaries forcing water and solutes through filtration slits
Glomerular Blood Hydrostatic Pressure (GBHP)
-Pressure exerted against the filtration membrane by fluid already in the capsular space
Capsular Hydrostatic Pressure (CHP)
Blood Colloid Osmotic Pressure (BCHP)-Pressure exerted by the proteins in blood plasma
-Regulates the blood flow to and within the glomerulus
-Responds to changes in blood pressure and plasma sodium concentration
-Juxtaglomerular apparatus: (?)
Renin-Angiotensin-Aldosterone System (RAAS)
juxtataglomerular cells + macula densa
Effects of Angiotensin II
-Release of (?) to increase Na reabsorption (DCT)
-Release of (?) to increase water reabsorption (CD)
-constriction of (?) to increase blood pressure
ALDOSTERONE
Antidiuretic Hormone (ADH)
efferent arterioles