Kidney structure and function Flashcards
What is the function of kidneys?
Process blood and rid the body of the waste products of metabolism via urine
Maintain internal homeostasis of fluid
What do kidneys play an important role in?
Blood Pressure
Acid/base ratio
Calcium/vitamin D metabolism
Erythropoietin (formation rbc)
What is the function of the ureters?
Transfer urine from kidney to bladder
Are kidneys retroperitoneal?
yes
What is the fatty tissue that kidneys are stored in?
Renal fat pad
What is the function of the cortex?
Contain 85% of kidney tubules (nephrons)
What is the function of the medulla of kidney?
Where urine is concentrated
Prevents excessive water loss
What is the function of the pelvis of the kidney?
Collection areas for urine which is funnelled into the ureter
What artery delivers blood to the kidneys from the abdominal aorta?
Renal artery
What is the capillary bed of the kidneys called?
Glomerular capillaries
What is the function of the peritubular capillaries?
Water reabsorption
Provides nutrients to kidneys
What is the basic functional unit of kidney?
Nephron
What is the function of the glomerulus and Bowman’s capsule?
Site of plasma filtration
What are the two types of nephron?
Cortical nephron (located in cortex)
Juxtamedullary nephrons (next to medulla, long loops of Henle)
Why is it important that the capilarries within glomerulus are ‘leaky’?
Allows for rapid filtration
What is the specialised epithelium found in the Bowman’s capsule?
Podocytes
What is the glomerulus and bowman’s capsule known as?
Renal corpuscle
What forms the filtration barrier?
Glomerular endothelium
Basement membrane
Pedicels of podocytes
What is the permeability of the filtration barrier?
Freely permeable to water and small molecules but not large proteins or cells
How does unfiltered blood arrive at the glomerulus?
Via the afferent arteriole
How is filtration through the filtration barrier facilitated?
Through a pressure gradient
What is filtered through the filtration barrier?
Urea
Creatinine
Water
Glucose
Amino acids
Na+
Cl-
etc
What is the glomerular filtration rate (GFR)?
The rate at which blood is filtered through the glomerulus into the bowman’s capsule
What can the glomerular filtration rate be influenced by?
Hydrostatic pressure
Osmotic pressure
Blood pressure
Renin-angiotensin system
Disease
What is the normal health glomerulus filtration rate?
125ml/min (180l a day)
What can be used to estimate the GFR?
Serum creatinine (and urea) measurements
How much of the filtrate is reabsorbed?
99%
What is the renal tubule made up of?
Proximal convoluted tube
Loop of henle
Distal convoluted tubule
Collecting duct
What is the function of the renal tubule?
Reabsorption and secretion
What can you find on apical surface of proximal convulated tubule?
Cilia
What capillaries are closely associated with the convoluted tubule?
Peritubular capillaries
What substance is NOT reabsorbed in the proximal convoluted tubule?
Creatinine
What is the reabsorption of water facilitated by?
Presence of aquaporins in membrane
How do glucose and amino acids move across the apical surface?
Sodium co transporters via passive diffusion
What does the proximal tubule use to reabsorb 2/3 of filtrate?
Na+K+ Pump on basolateral membrame
How does the Na+K+ pump work?
Use ATP to carry Na against the concentration gradient
What can the Na+K+ pump transferring the nutrients be known as?
Facilitated passive transport
What process do juxtamedullary nephrons take part in?
Counter-current multiplication
What are the three sections of the loop of henle?
Thin descending limb
Thin ascending limb
Thick ascending limb
What is a rule about both thick and thin ascending limbs?
DO NOT contain aquaporins and are IMOERMEABLE to water
What is the thick ascending limb the site of?
Active Sodium reabsorption, water does not follow
How is sodium reabsorbed in the thick ascending limb on apical membrane?
NKCC2 Pump
What happens to the medulla due to the the sodium reabsorption?
Very salty which allows water to move out tubule by osmosis
What happens to the concentration of the filtrate as it descends the thin descending limb?
More concentrated
What is the main aim of the loop of henle?
Reabsorb and retain water
In the medulla, how many litres of filtrate is reabsorbed?
45l
What supports the concentration gradient in the medulla?
Vasa recta
What is the function of the distal convoluted tubule?
Site of fluid volume and electrolyte regulation
What hormone is used to increase water absorption?
Antidiuretic Hormone (Vasopressin)
How does ADH act on distal and collecting tubules?
Insertion of aquaporins allowing water to be reabsorbed from the filtrate
What hormone signals the cells of the distal convoluted to reabsorb salt?
Aldosterone
What kind of hormone is aldosterone?
Steroid hormone
What hormone is released when their is an increase in blood pressure?
Atrial Natriuretic Hormone
How does ANP act on distal and collecting tubule?
Counteracts effects of ADH and aldosterone
By what process is sodium reabsorbed across the basolateral surface of epithelial cells lining the proximal convoluted tubule?
Active transport
What is the primary purpose of counter current multiplication?
Water reabsorption
What is blood filtering through the bowman’s capsule influenced by?
Glomerular hydrostatic pressure
Capsular hydrostatic pressure
Glomerular osmotic pressure
Systematic blood pressure
Ren-angiotensin-aldosterone system
Disease
What is the group of specialised epithelial cells which respond to the change in sodium concentration?
Macula densa
What is the name of the modified smooth muscle cells which modify the diameter of the afferent arteriole?
Juxtaglomerular cells
What are the function of mesangial cells?
Supporting cells
What do the macula densa release when sodium concentration is high?
Adenosine
Vasoconstrict
Does the macula densa have any effect on systemic blood pressure?
No
What do the macula densa release when sodium concentration is low?
Prostaglandins
What does an decrease in blood pressure cause the afferent arteriole to do?
Causes juxtaglomerular cells to secrete renin which activates the renin-angiotensin system
How does the renin angiotensin system restore blood pressure?
-angiotensin is in circulation
-the release of renin converts angiotensin into angiotensin I
-Angiotensin converting enzyme converts angiotensin I into angiotensin II
-Angiotensin II is a potent vasoconstrictor, rapidly increasing blood pressure
Where is angiotensin converting enzyme primary produced?
The vascular endothelium of lung
Where else does angiotensin II have receptors?
-Arterioles (constriction)
-Hypothalamus (thirst)
-Pituitary gland (release ADH)
-Adrenal medulla (release aldosterone)
What hormone is released to counteracts the renin angiotensin system?
Atrial natriuretic peptide (ANP)
Where do you find ANP?
The heart
What receptors in the heart detect change in blood pressure?
Baroreceptors
What is chronic kidney disease a main cause of?
Cardiovascular disease
Hypertension
What are causes of chronic kidney disease?
Hypertension
Diabetes
High cholesterol
Infections
Kidney stones
Long term use of Anti-inflammatory drugs
Symptoms of Chronic kidney disease?
Nausea
Oedema
Blood/protein in urine
Anaemia
Weak and painful bones
Hypertension
How do patients regulate hypertension?
Diet
Anti-hypertensive treatments
Diuretics (furosemide)
Aldosterone agonists (inhibit effect)
Angiotensin receptor blockers
What is the target for furosemide?
NKCC2 pumps
What is dialysis?
Artificial removal of waste , solutes, water and toxins from blood
What are the 2 main types of dialysis?
Haemodialysis
Peritoneal dialysis
