Renal System Flashcards
______ is key to maintaining Homeostasis.
The Kidney
How does the Kidney help maintain homeostasis?
- Excretes wastes and drugs
- Regulates or balances intake and excretion.
- Gluconeogenesis
- removal of foreign chemicals
- Regulates salts and water
- Production of Erythropoietin, Renin and 1,25-dihydroxyvitamin
_______ acts in the bone marrow to stimulate the synthesis of New erythrocytes.
Erythropoietin
_______ is helpful in regulation blood pressure.
Renin (via renin-angiotensin-aldosterone cascade)
_______ regulates calcium absorption.
1,25-dihydroxyvitamin D
________ requires Hemodialysis.
ESRD (End Stage Renal disease)
What is the main problem of ESRD?
Inability to get rid of nitrogenous waste (Urea) and ends up turning it in to ammonia which is toxic to humans.
What are the clinical manifestations of Renal disease?
- Ammonia breath
- Gingival Enlargment
- Xerostomia
- Tooth problems
- Premature loss
- Narrowing pulp chambers
- necrosis beneath fillings or crowns.
What are contraindications for ESRD patients?
Nephrotoxic drugs such as tetracycline, acyclovir, aspirin and NSAIDS.
- Increased susceptibility to bleeding due to destruction of platelets.
What is the basic structure of the kidney?
Renal medulla = center = portions of nephron tubule involves with concentration and collection of urine.
Renal Cortex = outer part = blood is filters in the glomeruli and filtrate passes through tubule of nephron.
Tubules drain to ____.
into renal pelvis and then into ureter
Ureters drain to _____.
Urinary bladder, and the bladder is drained by the urethra.
What is the functional until of the kidney?
The Nephron
Describe the structure of a nephron….
A cluster of capillaries and a long hollow tube with a wall that is one cell layer thick.
- Renal Corpuscle = glomerulus + capsule
- Proximal (Convoluted) Tubule
- Distal convoluted tubule
- Collecting duct (shared by several nephrons.
What are the 2 types of nephrons?
- Superficial or cortical nephrons
- Juxtamedullary nephrons
* Differ in position of the renal corpuscle and length of the medullary tubules.
What are the 3 steps of the Renal process?
- Filtration = solutes pass in from the blood into the tubular fluid in the renal capsule (bowman’s space)
- Secretion = substances are transported from the blood in the peritubluar capillaries into the tubular fluid.
Resorption = substances are transported defrost he tubular fluid into the blood in the peritubular capillaries.
Where does filtration occur?
in the glomerular capillaries (15-20% of plasma entering the glomerulus is filtered)
Blood leaving the glomerular capillaries flows into _________.
Peritubular capillaries (Vasa recta) *See diagram
Where does secretion and absorption take place?
Throughout the length of the tubules, Thus the composition of the tubular fluid varies with tubular region.
What happens to the tubular fluid that remains at the end of the collecting ducts?
it gets excreted.
_______ is a dense capillary bed where filtration occurs.
Glomerulus
_____ surrounds the glomerulus.
Renal capsule
What mechanisms regulate blood flow through the glomerulus?
- Smooth muscle contaction in afferent and efferent arterioles
- Response of Juxtaglomerular apparatus = secretes the hormone renin, which regulates BP and therefore glomerular blood flow.
- Sympathetic nervous system
What does the Proximal convoluted tubule do?
- Drains the renal capsule
- resorbs 2/3 of filtered salt and water
- Resorbs all filtered glucose and AAs
- Some diuretics act here.
What does the Loop of Henle do?
Site of countercurrent multiplication needed to produce concentrated urine, but the loop itself produces a dilute filtrate.
*Very powerful diuretics work here.
What are the parts of the loop of Henle?
Thin descending limb
Thin ascending limb
Thick ascending limb
What does the Distal convoluted tubule do?
- Drains the loop of henle
- regulates calcium
- site of action for some diuretics
What does the Collecting duct do?
collects fluid from multiple nephrons and extends from cortex through the medulla.
- regulates sodium, potassium and water.
- some diuretics act here
_____ Represents the volume of plasma form which all of a particular substance is removed to the urine.
Renal clearance (EX. 100ml/min)
Why is renal clearance clinically important?
It can be used to measure the globular filtration rate (GFR) based on 3 criteria:
- The substance must be freely filter in the glomerulus.
- The substance is not secreted
- The substance is not reabsorbed.
What is the GFR in normal kidney?
125ml/min or 180L/day
_____ and ____ are used in measure of renal clearance.
Insulin and creatinine
Tell me about insulin…..
It is a small polysaccharide that is freely filtered indent secreted of absorbed.
Tell me about creatine….
Product of muscle metabolism, freely filtered, not reabsorbed, almost no secretion.
Creatine level above ___ require dialysis.
10mg/dl
Glomerular capillary filtrate is ______ and _____.
Acellular and protein free.
What molecules are freely filtered in the glomerulus?
Glucose, salts, and AA’s
What determines if something is freely filtered?
Size = less than 20 A is freely filtered.
Charge = negatively charged molecules are not freely filtered.
Filtration occurs due to what?
Pressure differences btwn the blood in the capillaries and the fluid in the capsule. Pressure comes from 2 sources:
- Hydrostatic pressure = due to fluid in capillaries
- Oncotic pressure = Due to solutes in fluid.
Net filtration favors ________.
Filtration from blood into the capsule.
What affects GFR?
Blood flow into and out of the Glomerulus and P gradient is critical to maintain filtration.
Does Renal Blood flow (RBF) change much?
No it remains fairly constant despite changes in systemic BP. This is good because it means that GFR remains fairly constant as a result.
What is autoregulation?
Intrinsic mechanisms that regulate blood flow through the glomerulus.
What 2 mechanisms are responsible for autoregulation in the glomerulus?
- Myogenic mechanism = vascular smooth muscle tends to contract when stretched.
- Tubuloglomerular feedback = feedback from the JGA adjust afferent arteriole diameter and thus GFR.
Increase in GFR = ?
Increase in NaCl in tubular fluid = increase in NaCl at macula dense = Increased resistance in afferent arterioles = decrease in GFR.
What extrinsic factos regulate RBF and GFR?
- diet
- Dehydration or hemorrhage
- Sympathetic nervous system
- Angtiotensin II, aldosterone and natriuetic peptide.
