Overview of Kidney, Nephron Anatomy and Function

Question 1

Functions of the Urinary System

Answer 1

1. REgulation of Body Fluid Volume - conserving or eliminating water
2. Regulation of Fluid Osmolality and Composition - Na+, K+, Ca++, Cl-
3. Waste Removal (metabolism by products - nitrogenous wastes(urea), acids)
4. Endocrine - Renin(cascade for BP) Erythropoieten (RBC production)
5. Territory/Sex marker

Question 2

Components of Urinary System

Answer 2

1. Vascular System
2. 2 kidneys
3. 2 ureters
4. 1 bladder
5. 1 urethra

Question 3

Amount of plasma filtered per day

Answer 3

180 L or 45 gallons

Question 4

Amount of Urine excreted per day

Answer 4

1.5 L

137 gallons per year, 10265 gallons per life

Question 5

% of blood flow goint to the kidneys

Answer 5

25% of cardiac output

1250mL/min, 5mL/min/gram of kidney

Question 6

Kidney

Answer 6

paired, bean shaped organ, 4.5 inches long, retroperitoneal sposition(Tt12-L3), ureters depart from the Hilus, functional unit is Nephron

Question 7

Primary Kidney Function

Answer 7

conservation and filtration of fluid

cannot restore lost volume

Question 8

Gross Anatomy

Main Kidney Parts

Answer 8

1. Capsule
2. Cortex
3. Medulla
4. Pelvis

Question 9

Kidney

Capsule

Answer 9

provides protection to the Kidney

tough fibrous layer that surrounds the kidney

Question 10

Kidney

Cortex

Answer 10

where ultrafiltration and erythropoietin production occur, contains cortical arches and renal columns

between the capsule and medulla

Question 11

Renal Columns

Answer 11

consists of blood vessels and urinary tubes

medullary extension of renal cortex in between renal pyramids

Question 12

Kidney

Medulla

Answer 12

8-18 renal pyramids, contains Nephrons

innermost part of the kidney

Question 13

Renal Calyces

Answer 13

pacemaker cells that stimulate peristalsis which propels urine

Question 14

Nephron

Answer 14

funcitonal unit, 1-3 million per kidney, 3 cm long

Question 15

Functions of Nephron

Answer 15

1. Filtration of Blood Plasma(concentration)
2. Reabsorbtion of water, AA’s, sugar, salts(Acidification)
3. Secretion of H, K ions

these funcitons allow urine concentration and acidification

Question 16

Cortical Nephrons

Answer 16

start high in the cortex and have a short loop of henle that does not deeply penetrate the medulla

majority of Nephrons

Question 17

Juxtaglomerular Nephrons

Answer 17

cells that produce Renin

produces renin in response to B1 receptors, decrease in renal profusion, decrease in NaCl concentration in the macula densa

Question 18

5 Principle Nephron Parts

Answer 18

1. Renal Corpuscle
2. Proximal Concoluted Tubule
3. Loop of Henla
4. Distal Convoluted Tubule
5. Collecting Duct

Question 19

Renal Corpuscle

Answer 19

primary function is filtration

Renal Corpuslce = Glomerulus + Bowman’s Capsule

Question 20

Glomerulus

Answer 20

fenestrated(leaky) capilary exchange unit, Filtration Funciton

simple squamous, basal lamina, podocytes, mesangial cells

Question 21

Afferent Arteriole

Answer 21

incoming flow into glomerulus

smooth muscle that is resistant to Angiotensin 2(vasoconstrictor)

Question 22

Efferent Arteriole

Answer 22

outgoing flow from the glomerulus

only the kidney has capillaries that are drained by arterioles

smooth muscle that is activated by Angiotensin 2(vasoconstrictor)

Question 23

Bowman’s Capsule

Answer 23

collects fluid from the glomerulus

Question 24

Proximal Convoluted Tubule

Answer 24

85% Reabsorbtion of water, Na, AA, and glucose

glucose coupled with Na+ for transport

Glucose = Tm=375 mg/dl in men 300mg/dl in women, Tm=maximum amount to reabsorb glucose in urine

Question 25

What does glucose in urine signal?

Answer 25

Diabetes

Question 26

Loop of Henle

Answer 26

creates salt interstitum, ultimate goal is water reabsorbtion and creating more concentrated urine

Question 27

Counter Current Multiplier

Answer 27

salt concentraiton increases as it goes down, creates a concentration gradient | Loop of Henle ## Footnote thin descending limb: water permeable thick ascending limb: Na+ permeable

Question 28

Counter Current Exchanger

Answer 28

Vasa Recta/Peritubular Capillaries

Question 29

Disatal Convoluted Tubule

Answer 29

responsible for secretion, acidification, and reabsorbtion ## Footnote helps with the Renin/Angiotensin/Aldosterone System

Question 30

# Kidney Secretion

Answer 30

the movement of selected molecules from the blood into the nephron ## Footnote filters K+ with Aldosterone much of the time

Question 31

Excretion formula

Answer 31

Filtration - Reabsorbtion + Secretion

Question 32

Acidification

Answer 32

???

Question 33

Reabsorbtion

Answer 33

movement of filtered material from the lumen of the nephron to the blood ## Footnote occurs when proximal tubule cells transport solutes out of the lumen, water follows via osmosis

Question 34

Macula Densa

Answer 34

specialized cells in the distal tubule wall that monitor fluid flow through the tubule

Question 35

JG Apparatus

Answer 35

region where the distal tubule of the nephron passes between afferent and efferent arterioles

Question 36

Renin

Answer 36

peptide secreted by juxtaglomular cells that converts angiotensinogin into angiotensin 1

Question 37

Collecting Duct

Answer 37

terminal region of the kidney tubule, permeable to water ## Footnote last 15% of water reabsorbed

Question 38

ADH

Answer 38

Anti Diuretic Hormone, supraoptic nuclei of Hypothalmus, stored and released by Posterior Pituitary

Question 39

No ADH

Answer 39

87% total water reabsorbtion, would lead to 24L of excretion per day, Diabetes Isipidus, ## Footnote alcohol inhibits ADH release

Question 40

Normal ADH levels

Answer 40

98.7% water reabsorbtion, 1.5L of excretion per day

Question 41

Maximum ADH

Answer 41

99.7% water reabsorbtion, 0.5L of excretion per day

Question 42

# Osmo Osmoreceptors

Answer 42

in the Hypothalmus, regulate ADH output ## Footnote osmoreceptors shrink = increase plasma osmolality 1-2%, hypovolemia, increased thirst and ADH release

Question 43

Tubular Excretory Components

Answer 43

1. Ureter 2. Bladder 3. Urethra

Question 44

Ureter

Answer 44

propels urine via peristaltic wave(ureters function without gravity), run obliquely thru bladder wall, forms valve(prevents backflow) ## Footnote paired, 10-12 inches long, retroperitineal, 3 layers(mucosa, muscularis, fibrous)

Question 45

Bladder

Answer 45

detrusor muscle-smooth muscle, Trigone: 2 ureter input + urethra outflow ## Footnote in pelvis, posterior to pubic symphysis, male anterior to rectum, female anterior to uterus

Question 46

Urethra

Answer 46

2 parts Internal Urethral Sphincter (smooth m.) External Urethral Sphincter (skeletal m.)

Question 47

Female Urethra

Answer 47

excretory funciton only, emptys via gravity, infection prone ## Footnote short - 1.5 inches,

Question 48

Male Urethra

Answer 48

excretory + reproductive function(joined by 2 ejaculatory tracts) ## Footnote prostatic(travels through prostate), membranous(external urethral sphincter), cavernous(in Corpus Spongiosum)

Question 49

Micturition(urination)

Answer 49

bladdder fills, proprioceptors maintain tonus, involves both sympathetic and parasympathic paths, parasympathetic is more important. ## Footnote 200-300mL will make the individual aware of the desire to urinate

Question 50

Reflex Urination

Answer 50

1. above 200mL of urine 2. detrusor muscle contracts 3. internal and external sphincters relax 4. bladder empties ## Footnote infants, spinal cord injuries

Question 51

Atonic Micturition

Answer 51

detrusor muscle tone lost ## Footnote incontinence and dribbling

Question 52

Controlled Micturition

Answer 52

Cerebral Cortex inhibits contraction of detrusor muscle, relaxation of sphincters