Renal anatomy

Question 1

role of renal system

Answer 1

maintain water and chemical balance in body by expelling excess water. salts, wastes of metabolism, toxins and drugs. Also has endocrine functions to produce EPO and renin

Question 2

requirements of renal system

Answer 2

delivery system for blood

selective filtration system

filtrate recovery mechanism

system to remove filtrate from body

protection; ability to communicate

Question 3

structure of renal system

Answer 3

2 kidneys, 2 ureters, urinary bladder, urethra, regulatory nerves and muscles

Question 4

location of kidney

Answer 4

located between T12-L3 vertebrae and underneath 11th and 12th ribs.

Located on posterior abdominal wall covered on anterior side by peritoneum.

Surrounded by protective renal fat.

Right kidney slightly inferior because of liver

Question 5

gross structure of kidney

Answer 5

fibrous capsule - outermost, protection

cortex - outer, renal columns between medullary pyramids

medulla - inner, divided into medullary pyramids, each pyramid ends in papilla

Question 6

renal lobe

Answer 6

one emdullary pyramid and surrounding cortex

usually between 5 and 11 per kidney

Question 7

path of urine out of kidney

Answer 7

urine drains from each papilla and collects in a calyx

calyxes join to form renal pelvis

pelvis narrows as it exits the hilum to become the ureter

ureters flow into bladder

urethra exits bladder

Question 8

blood supply into the cortex

Answer 8

Abdominal aorta –> renal artery –> Series of arteries –> afferent arteriole –> glomerular capillary

Question 9

blood flow away from cortex after being filtered

Answer 9

Glomerular capillary –> efferent arteriole –> peritubular capillaries –> series of veins –> renal vein –> inferior vena cava

Question 10

peritubular capillaries

Answer 10

specialised for absorption

adjacent to renal tubules

at low pressure and porous

Question 11

innervation of kidneys

Answer 11

innervated by a network of autonomic nerves and ganglia called renal plexus

supplied by sympathetic nerve fibres from splanchnic nerves

determines diameter of renal arterioles so regulates blood flow

Question 12

what is a nephron and functions

Answer 12

microscopic functional unit of kidney

functions are:

1. filter blood
2. reabsorb certain substances
3. secrete into filtrate
4. excrete waste

Question 13

cortical nephron

Answer 13

85% of nephrons

Lie mainly in the cortex - do not extend far into the medulla

Question 14

juxtamedullary nephrons

Answer 14

Extend deep into the medulla

Important for the formation of concentrated urine - the deeper a nephron penetrates into the medulla, the more concentrated the urine it will produce.

Their loop of Henle’s are associated with a vasa recta

Question 15

structure of nephron

Answer 15

bowman’s capsule - filtration

proximal convoluted tubule - bulk reabsorption

loop of Henle - HOMG

distal convoluted tubule - fine tuning

collecting duct

Question 16

glomerular capillaries

Answer 16

Specialised for filtration

Thin walled single layer of fenestrated endothelial cells

Fed and drained by arterioles

High pressure and tightly regulated

Question 17

two layers of Bowman’s capsule

Answer 17

1. Outer parietal layer of simple squamous epithelium
2. Inner visceral layer of podocytes

Between two layers is Bowman’s space

Question 18

podocytes

Answer 18

Surround glomerular capillaries

Very branched, specialised epithelium

Branches form intertwining foot processes called pedicels

Filtration slits form between pedicels

Filtered blood goes through these slits and passes into Bowman’s space

Question 19

filtration barrier

Answer 19

Lies between blood and Bowman’s space

Allows free passage of water and small molecules

Restricts passage of most proteins

RBCs are not filtered into nephron

Question 20

3 layers of filtration barrier

Answer 20

1. Fenestrated endothelium of glomerular capillaries
2. Fused basement membrane of glomerular capillaries and podocytes
3. Filtration slits between pedicels of the podocytes

Question 21

structure and function of proximal convoluted tubule

Answer 21

Cuboidal epithelial cells

Brush border (dense microvilli) on the luminal membrane

Highly folded basolateral membrane

Many mitochondria for active transport

Leaky epithelium to facilitate bulk reabsorption

function = bulk reabsorption

Question 22

structure and function of thick ascending limb of LoH

Answer 22

Structure: similar to PCT (cuboidal epithelial cells with a brush border on the luminal surface, a highly folded basolateral membrane, and many mitochondria)

Function: reabsorption of water from filtrate

Question 23

structure and function of thin descending limb of LoH

Answer 23

simple squamous epithelium

reabsorption of water from filtrate

Question 24

structure and function on thin ascending limb

Answer 24

simple squamous epithelium

reabsorption of salt (NaCl) from filtrate

Question 25

structure and function of thick ascending limb

Answer 25

similar to DCT (thinner cuboidal epithelial cells with no brush border, and fewer mitochondria than the PCT) reabsorption of salt (NaCl) from filtrate

Question 26

distal convoluted tubule

Answer 26

cuboidal epithelial cells but thinner than those in PCT few microvilli - no brush border fewer mitochondria than PCT

Question 27

function of DCT

Answer 27

reabsorption of various substances - fine tuning influenced by aldosterone

Question 28

structure of collecting duct

Answer 28

wall of simple cuboidal epithelial cells - 2 types: 1. principal cells - reabsorption 2. intercalated cells - acid/base balance filtrate from several DCTs drains into one collecting duct, which then empties into a papilla

Question 29

function of collecting duct

Answer 29

fine tuning of urine Reabsorption is influenced by antidiuretic hormone (ADH) through the use of aquaporins

Question 30

juxtaglomerular apparatus

Answer 30

specialised zone in every nephron, located where the DCT lies against the afferent arteriole. ``` Both vessels have specialised cells that control the glomerular filtration rate (GFR). ``` stabilises blood pressure

Question 31

juxtaglomerular cells

Answer 31

found on afferent arteriole mechanoreceptors release renin in response to BP, which stimulates formation of angiotensin II

Question 32

macula densa

Answer 32

found on DCT chemoreceptors sense NaCl concentrations

Question 33

transitional epithelium

Answer 33

epithelium of urinary system specialised type of stratified epithelium It is made up rounded cells that flatten when they are stretched Transitional epithelium functions to protect the structures that it lines

Question 34

3 layers of ureters

Answer 34

1. transitional epithelium - innermost 2. muscularis - inner = longitudinal, outer = circular 3. adventita - outer, FCT also have protein plaques on luminal surface

Question 35

entry of ureters into bladder

Answer 35

Enter bladder at an oblique angle, which acts as a sphincter/valve as it can be compressed by increased bladder pressure when full to prevent backflow

Question 36

exit of ureters from kidney

Answer 36

Arise from each renal pelvis at each hilum Descend retroperitoneally through abdomen, vertically from hila

Question 37

triangular region between 3 openings of bladder

Answer 37

trigone - often does not fully empty so prone to infection

Question 38

expansion of bladder

Answer 38

When empty the bladder collapses along folds or rugae When full, the bladder expands without great increase in pressure

Question 39

features of empty bladder

Answer 39

pyramidal lies in pelvis

Question 40

features of full bladder

Answer 40

more spherical expands superiorly into abdominal cavity

Question 41

location of bladder in males and females

Answer 41

males: anterior to rectum, superior to prostate females: anterior to vagina and uterus

Question 42

3 layers of bladder wall

Answer 42

1. transitional epithelium 2. detrusor muscle 3. adventitia

Question 43

detrusor muscle

Answer 43

specialised type of smooth muscle that squeezes urine from the bladder during urination It is composed of longitudinal, circular and oblique fibres in a disorganised arrangement

Question 44

urethra

Answer 44

thin-walled muscular tube that drains urine from the body and expels it out of the body

Question 45

changes in epithelium in urethra

Answer 45

Transitional epithelium near the bladder Columnar epithelium in the middle Stratified squamous epithelium near the external opening - for protection

Question 46

2 urethral sphincters

Answer 46

internal urethral sphincter - junction of bladder and urethra, detrusor muscle under parasympathetic control (involuntary) external urethral sphincter - where urethra passes through urogenital diaphragm, skeletal muscle under somatic control (voluntary)

Question 47

urination reflex

Answer 47

Bladder fills with urine and expands AP to brain Urgency increases as signals increase Inner sphincter relaxes Conscious relaxation of external sphincter Issues with control - pregnancy, other issues leading to incontinence

Question 48

male urethra

Answer 48

longer (25cm) part of reproductive system 3 sections: prostatic, membranous, spongy/penile

Question 49

urethra in females

Answer 49

shorter (5cm) separate from reproductive system