Renal System Flashcards
Describe the urinary system.
Consists of paired kidneys, 2 ureters, bladder and urethra
Role is to maintain optimal properties of blood
Function - filtration to separate out which should be absorbed and which should be excreted
This maintains homeostasis
Functional units are nephrons
Describe the structure and function of the kidneys.
Right kidney slightly lower than left due to liver
Extend from level T12 to L3
Hilum is the concave medial border in the kidney where renal blood and lymph vessels, ureter and nerve vessels enter and leave
Adrenal glands are present on the superior pole of kidney
Kidneys are multi lobar and each lobe is divided into an outer cortex and inner medulla with renal papilla
Papillae release urine to minor calyces
Cortex associated with renal corpuscles and the renal tubules of the nephron
Medulla characterised by straight tubules, collecting ducts and vasa recta
Renal columns represent cortical tissue contained within the medulla
Vascular pole contains DCT, macula densa, juxtaglomerular cells, afferent arteriole
Renal pole contains PCT, efferent arteriole.
Describe the structure of the nephron
Nephrons consist of the renal corpuscle and the renal tubule.
Renal corpuscle;
Bowman’s capsule - surrounds glomerulus and collects the filtrate that is produced by the glomerulus and channels it into the renal tubule
Glomerulus
Renal tubule;
Proximal convoluted tubule
Distal convoluted tubule -
Loop of Henle - descending + ascending limb
Collecting duct - final adjustments to urine composition and volume, under the influence of ADH
Vascular supply;
Peritubular capillaries at efferent arteriole of the glomerulus
Vasa recta - specialised capillaries that extend into the medulla
What are the 2 types of nephrons?
Cortical - don’t extend deep into the medulla
Juxtamedullary - extend deep into the medulla.
What are the components of the juxtaglomerular apparatus?
Specialised endocrine structure made from grouping of cells from distal convoluted tubule and glomerular afferent arteriole
Macula densa in the distal convoluted tubule contains sodium detecting cells
Mesangial cells provide physical support for capillaries
Juxtaglomerular cells are specialised smooth muscle cells that store and secrete renin.
Describe the operation of the juxtaglomerular apparatus.
Secretion of renin by smooth muscle cells of afferent arterioles acts on angiotensin and converts it to angiotensin 1
Angiotensin converting enzyme produces angiotensin 2
Angiotensin 2 causes constriction of arterioles increasing blood pressure
Adrenal gland releases aldosterone which increases absorption of Na+ and Cl- ions
This increases fluid in the blood thus increasing blood pressure
Describe the structure of the glomerular filtration barrier.
Fenestrated capillary epithelium is negatively charged and repels plasma proteins
Thick basement membrane also negatively charged
Foot processes of the podocytes is the final barrier
Describe the structure and function of the ureter.
Lined by urothelium (transitional epithelium)
When empty stratified cuboidal
When full, stratified squamous
Ureters are muscular tubes extending from kidneys To the base of bladder
Muscular peristaltic waves convey urine to the urinary bladder
3 points of constriction.
Describe the structure and function of the Loop of Henle.
Thin descending limb and thick ascending limb
Responsbile for osmoregulation via a salt gradient
Thick limbs - simple cuboidal epithelium
Thin limbs - no red blood cells
Describe the structure and function of the proximal convoluted tubule.
Brush border of microvilli
Numerous basally located mitochondria
Na+, Cl- are reabsorbed here
Apical tubulo-vesicles
Describe the structure and function of the distal convoluted tubule
Simple cuboidal cells
Mitochondria for active transport
No microvilli
Basal infolding
Function is maintenance of acid-base balance
in the blood.
