The Renal System Part 1

proximal convoluted tubule

-branches off the renal corpuscle -site at which most of the tubular reabsorption occurs -feeds into descending loop -located entirely within cortex -simple cuboidal epithelium with microvilli

ureter

-carries urine out of the kidney and into the bladder -capable of peristalsis -connects to the bladder at an angle that prevents backflow of urine

descending limb of loop of henle

-contains fluid that becomes more concentrated as it moves down into the medulla -feeds into the ascending limb -alternates between thick and thin segments B

mucosa of ureter

-deepest layer of the ureter tissue -transitional epithelium (urothelium) -readily stretches to accommodate distension from urine filling

osmosis

-diffusion of water across a selectively permeable membrane -high concentration to low concentration

renal capsule

-directly covers the outer surface of the kidney -CT capsule

uterus

-expands with fetus during pregnancy -compresses bladder to increase frequency of urination

renal corpuscle

-first site of filtration off the afferent arterioles -glomerulus and bowman's capsule -converges into PCT

renal medulla

-inner region of the kidney -composed of medullary/renal pyramids

extracellular fluid

-interstitial (10.5L) + intervascular fluid (3.5L) -comprised 14L of the total body H2O -far less protein, electrolytes -pH= 740 (more basic) -Na+ most common

perinephric/perirenal fat capsule

-layer of adipose tissue on kidneys

urethra in females

-length of 3-5 cm -functions only in the transport of urine

anatomy of the kidneys

-located in the retroperitoneal space (behind the peritoneum) -extends from T12 to L3 -protected by the floating ribs (R12) -left kidney sits higher

urethra in males

-longer than females (20cm) -conveys both urine and semen -three parts: prostatic urethra, membranous urethra, penile/spongy urethra

muscularis of ureter

-middle layer of the ureter tissue -senses distension with urine filling and triggers reflexive peristalsis to expel urine -detrusor

renal fascia

-most superficial layer of the kidneys -dense connective tissue -surrounds both kidneys and adrenal glands

adventitia layer of ureter

-most superficial layer of the ureter tissue -fibrous connective tissue -anchors the ureter in place

renal cortex

-outer region of the kidney -granular, reddish brown

Loop of Henle

-section of the nephron tubule that is responsible for conserving water and minimizing the volume of the filtrate -"Nephron Loop" -connects ascending and descending loops

internal urethral sphincter

-thick muscle near the urethra -involuntary contraction to expel urine

ascending limb of loop of henle

-thick segment moves ions out into interstitial spaces for reabsorption -connects to DCT -alternates between thick and thin segments D

external urethral sphincter

-urine passes through a ring of skeletal muscle -voluntary

intracellular fluid

-water, electrolytes, small molecules, non-electrolytes, proteins -20-30% protein -pH= 7.00 (neutral) -K+ most common

flow of fluid after filtration through the nephron

1. DCT: filtrate from many nephrons 2. collecting duct 3. principal cells: adjust urine in order to maintain body's water, NA+ and K+ balance 4. intercalated cells: responsible for acid-base balance 5. papillary duct to renal papilla 6. minor calyx

flow of fluid through the nephron's tubule

1. PCT 2. Descending tubule 3. Loop of Henle 4. Ascending tubule 5. DCT

flow of blood in the glomerulus

1. afferent arteriole 2. glomerular capillary (filtration) 3. efferent arteriole 4. peritubular capillaries (absorb fluid) 5. venule

interconnected fluid pools

1. aquaporin channels 2. osmolarity change

how do we lose water?

1. kidneys (60%) 2. sweat (8% and higher) 3. lungs (28%) 4. feces (4%)- increases with diarrhea -> leads to dehydration ***water loss increases with heat***

three connective tissue layers of the kidneys

1. renal fascia 2. perinephric/perirenal fat capsule 3. renal capsule

thirst

Generated by: -exercise, eating salty food, dry mouth -increase in osmolarity -blood loss -release of ADH (antidiuretic hormone)

true

T or F: 90% of the fluid is reabsorbed in the nephron

navicular fossa

an enlargement of the distal end of the urethra in the area of the glans penis

renal papilla

apex of renal pyramid, connects to minor calyx

arcuate arteries

arteries that branch off the interlobar arteries and supply cortical radiate arteries

lobar/segmental artery

blood vessel that branches off the renal artery

renal artery

blood vessel that carries blood to the kidney C

cortical radiate arteries

branch off the arcuate arteries and ascend into the cortex (microscopic afferent arterioles)

major caylx

collect urine and drain it into the renal pelvis

dehydration

excessive water loss via: -sweating, diarrhea, vomiting, little water ingestion

hypotonic hydration

ingestion of too much water

renal columns

inward extensions of the cortex tissue separating the renal pyramids, separate the renal pyramids

hypovolemia

loss of plasma volume in blood ex: diabetes, burns, wounds, vomiting

membranous urethra

portion of the male urethra between the prostate and the penis

penile urethra

portion of the male urethra that travels through the length of the penis

prostatic urethra

section of the male urethra where the urethra passes through the prostate.

interlobar arteries

segmental arteries further divide into these arteries which supply blood to the arcuate arteries

intracellular, intravascular, and interstitial fluid

the human body is composed of three interconnected pools that make up the majority of the total body H2O

collecting duct

the location in the kidney where processed filtrate, called urine, is collected from the renal tubules

nephron

the structural and functional unit of urine formation in the kidney

hypervolemia

too much plasma volume ex: renal or liver failure, ascites in liver

trigone

triangular area at the bottom of the urinary bladder marked by openings for the paired ureters and the urethra

juxtaglomerular apparatus

when a portion of the DCT comes into contact with the afferent arteriole (going into glomerulus) -consists of granular cells, macula densa cells

A and D: HCO3- and Na+

which of the following are electrolytes? a. HCO3- b. glucose c. CO2 d. Na+

located in the cortex; lined with simple cuboidal epithelium with microvilli

which of the following describes the PCT?

granular cells

-aka juxtaglomerular cells -apart of JGA -responds to changes in blood pressure in the afferent arteriole

aquaporin channels

-all cells express aquaporin channels -all cells allow for the movement of water as a function of osmolarity differences

macula densa cells

-apart of JGA -monitors concentration of Cl- and Na+ in filtrate

distal convoluted tubule

-Between the Loop of Henle and the collecting duct; Selective reabsorption and secretion occur here, most notably to regulate reabsorption of water and sodium -Marks the end of the nephron -simple cuboidal epithelium without microvilli

renal fascia, perirenal fat capsule, renal capsule

List the order of the connective tissue layers in the kidney, from superficial to deep

osmolarity change

a change in the osmolarity of any pool means that the osmolarity of all pools change

minor calyx

a cup-shaped extension of the renal pyramid that encircles the apex of a pyramid and collects urine