L23: Microanatomy of the Kidneys

filtration of blood

removal of metabolic waste

reabsorption

preserving necessary metabolites and nutrient and the required amount of water

what is the endocrine function of the kidneys?

production of renin

what is the functional unit of the kidneys?

the nephron

what is the kidney surrounded by?

dense connective tissue capsule

what is the parenchyma of the kidney divided into?

outer cortex and inner medulla

what are the general functions of the kidneys?

1. filtration

2. reabsorption

3. secretion

4. countercurrents

what is the flow of the urogenital tract?

1. kidneys

2. ureters

3. urinary bladder

4. urethra

5. penile urethra or vestibule and vulva

why does the outer cortex appear granular?

presence of renal corpuscles

what is important to understand about the lobes of the bovine kidney?

each lobe acts as an independent functional unit

where is the only place you will see lobation in a porcine kidney?

will only see internally

what is 1?

capsule

what is 2?

cortex

what is 3?

medulla

what is 4?

crest

what is 5?

renal pelvis

what is 6?

ureter

what components are part of the outer cortex?

1. renal corpuscles

2. pars convoluta

3. pars radiata

4. blood vessels

pars convoluta

proximal and distal convoluted tubules

pars radiata

collecting ducts that are partly in cortex and partly in medulla

what structure in the kidney is the renal corpuscles associated with?

glomerulus

what is 1?

capsule

what is 2?

renal corpuscle

what is 3?

pars convoluta

what is 4?

pars radiata

what is 1?

renal cortex

what is 2?

renal medulla

what is 3?

arcuate artery

what is 4?

bowman’s capsule

what is 5?

cortical glomerulus

what is 6?

efferent arteriole

what is 7?

afferent arterioles

what is 8?

interlobular artery

what is 9?

distal convoluted tubule

what is 10?

proximal convoluted tubule

what is 11?

junctional tubule

what is 12?

interlobular vein

what is 13?

intertubular capillaries

what is 14?

juxtamedullary glomerulus

what is 15?

loop of henle

what is 16?

collecting ducts

what is 17?

interlobar vien

what is 18?

interlobar artery

what is 19?

renal papilla

how is the proximal convoluted tubule different than the distal convoluted tubule on histology slide?

lumen not as clear because proximal has more microvilli to increase surface area for absorption

what is this histology representing?

proximal convoluted tubule

what is the black line on the histology representing?

renal corpuscle

what is the histology showing?

distal convoluted tubule

what structures are located in the inner medulla?

1. collecting ducts

2. descending and ascending thin segments of loop of henle

3. ascending thick segmenets of loop of henle

4. vasa recti

5. peritubular capillaries

MCQ: Considering the structure of the nephron, which structure will appear only in the section through the medulla of the kidney?

thin and thick limb of the Henle’s loop

what are the components in order of the nephron?

1. renal corpuscle

2. proximal convoluted tubule

3. proximal straight tubue

4. the loop of Henle/ hairpin loop

5. distal convoluted tubule

6. collecting

7. tubule

8. renal tubule

what structure is within the renal corpuscle?

glomerulus

what structures are within the loop of Henle?

1. think descending limb

2. thin ascending limb

3. thick ascending limb

what is another name for the proximal straight tubule?

thick descending tubule

what is another name for the thick ascending limb?

distal straight tubule

renal tubule

nephron and collecting duct system

what is 1?

Bowman’s Capsule

what is 2?

proximal convoluted tubule

what is 3?

distal convoluted tubule

what is 4?

proximal straight tubule

what is 5?

thick ascending limb

what is 6?

thin descending limb

what is 7?

thin ascending limb

what is 8?

cortex

what is 11?

inner medulla

what do 9 and 10 make up?

outer medulla

what does the vasa recta capillary surround?

Henle’s loop

efferent arterioles

branch away from the glomerulus to form secondary circulation component surrounding the nephron

afferent arterioles

only enter renal corpsucles to form glomerulus

in order list the microcirculation of the kidney.

1. interlobar arteries and veins

2. arcuate arteries

3. interlobar arteries

4. afferent arterioles

5. glomerulus

6. efferent arteriole

7. peritubular capillairies

8. vasa recti

9. venules

10. interlobar / arcuate veins

the efferent arteriole only supplies what part of the kidney?

only supplies to medulla from peritubular network

MCQ: what structure makes up the peritubular capillary network?

efferent arteriole

glomerulus

the tuft of the capillaries responsible for filtration of blood

bowman’s space

space between the visceral and parietal layers of Bowman’s capsule

what makes up the parietal layer of bowman’s capsule?

simple squamous epithelium

what makes up the visceral layer of bowman’s capsule?

podocytes

what is another name for bowman’s capsule

urinary space

where is pre-urine filtrate collected?

bowman’s space

what structures make up the renal corpuscles of the kidney?

1. glomerulus

2. bowman’s capsule

where does the urinary pole of bowman’s capsule continue to?

proximal convoluted tubule of nephron

what poles are in bowman’s capsule?

1. vascular pole

2. urinary poles

what is the function of the glomerulus?

filtration of the blood

what does it mean when we say “the glomerulus will have 20% filtrate of blood”?

approximately 20% of the plasma that flows into the glomerular capillaries via the afferent arteriole is filtered into Bowman’s space

how many liters of blood is circulated to produce 1 liter of urine?

100

what is in filtrate?

1. water

2. glucose

3. nutrients

4. bicarbonates

5. urea

6. creatine

7. small proteins

8. amino acids

what lines the renal calices and pelvis?

transitional epithelium and loose connective tissue

what is present under the epithelium of calices and pelvis in horses and what does this do to the urine of the horse?

1. mucus glands

2. have cloudy urine (mucus)

what are smaller collecting ducts lined by?

simple cubodial and lateral borders are clear

what is the larger collecting duct lined by?

simple columnar

what are the large white spots in the histology?

collecting ducts

what lines the papillary duct?

1. 2 layered epithelium

2. later becomes transitional

what are macula densa sensitive to?

chloride ions

what is the function of the macula densa?

regulate the filtration rate

juxtaglomerular apparatus

formed by the contact of the distal tubule and afferent tubule

where are macula densa located?

in distal tubules of juxtaglomerular apparatus

what cells are present in macula densa?

modified cubodial to columnar cells

where are juxtaglomerular cells located?

afferent arteriole of juxtaglomerular apparatus

what cells are present in juxtaglomerular cells?

modified smooth muscles

what cells make up the juxtaglomerular apparatus?

1. macula densa

2. juxtaglomerular cells

3. extraglomerular mesangial cells

what is the function of juxtaglomerular cells?

produce renin