Exam 1: Lecture 2 Flashcards
Crucial functions of the kidneys?
maintaining overall fluid and electrolyte and acid-base balance
filtering waste materials and reabsorbing needed materials
creating hormones that help produce red blood cells, promote bone health, and regulate blood pressure
Where is the glomeruli located?
Cortex
The ________ contains the majority of the nephrons (tubules), the main functional component of the kidneythat filters fluid from blood.
medulla
enlarged, cup-like portion of the ureter. Renal artery enters and ureter leaves through the renal hilus.
The renal pelvis
There are about _______ million nephrons in each kidney.
1.3
Each __________ is composed of: arenal corpuscle(glomerulus within Bowman’s capsule)
nephron
______ % of the blood leaving the left ventricle of the heart enters the kidneys via the renal arteries.
20-25
Blood passes through the kidneys at a rate of __________ , or _____ ml/min/kidney.
~1200 ml/min
600
Your blood circulates through your kidneys many times a day. In a single day, your kidneys filter about
______ liters of blood. Most of the water and other substances that filter through your glomeruli are returned to your blood by the tubules.
Only ________ become urine.
140
600 – 1800 mL
Urine formation consists of what 3 processes?
-Plasma filtration at glomeruli
-Reabsorption
-selective secretion by renal tubules
After filtration, the fluid
is called the ….
ultrafiltrate
Hydration and Ion Balance depends on what system?
Renin/Angiotensin/Aldosterone System (RAAS)
What is the driving force behind glomerular filtration?
High hydrostatic pressure of afferent arteriole.
Works with Bowman’s capsule to create a shield of negativity to retain proteins.
______________ is where Needed components (water and solutes) are returned to the body
Reabsorption
wastes are removed from the bloodstream and excreted in urine after adjusting acid-base equilibrium.
Secretion
Both reabsorption and secretion involve what type of transport?
passive and active transport
Some substances are completely reabsorbed or secreted; other depend on plasma level – called ___________ substances.
threshold
what is needed for active transport?
carrier proteins and energy
Glucose does not appear in the urine until plasma concentration exceeds ________ mg/dL.
160 – 180 mg/dL.
Examples of threshold substances
potassium, amino acids, ascorbic acid, urea (low threshold), but we are usually referring to glucose (high threshold)
reabsorbs ions, water, nutrients: removes toxins and adjusts filtrate pH
Proximal convoluted tubule
selectively secretes and absorbs different ions to maintain blood pH and electrolyte balance
distal tubule
reabsorbs solutes and water from the filtrate
collecting duct
aquaporins allow water to pass from the filtrate into the interstitial fluid
descending loop of Henle
reabsorbs Na+ and Cl- from the filtrate into the interstitial fluid
ascending loop of Henle
-The most essential substances in the filtrate are reabsorbed in the first half of the proximal convoluted tubule along with 70% of the water, K, Cl and urea (passive).
-glucose, amino acids/proteins, phosphate, lactate and citrate, Mg2+ , Ca2+ are actively transported.
Reabsorption in the proximal convoluted tubule
uses sodium/proton exchangers to carry sodium coupled with another solute across cell walls using membrane proteins.
Indirect active transport or co-transport
> 80% of filtrate reabsorption here with 67% of water and almost all glucose, lactose, amino acids, bicarb and half of urea, 65% Na and K. Mostly active transport.
Proximal Convoluted tubule
What is the main function of the loop of Henle?
is sodium and water recovery accomplished by creating a concentration gradient between cortex and medulla.
The main function of the distal and collecting tubules is…
adjustment of the pH, osmolality, and electrolyte content of the urine as well as the regulation of those substances still present in the filtrate. Potassium, ammonia, and hydrogen ions are secreted by this portion of the nephron, while sodium and bicarbonate are reabsorbed by the same mechanism as in the proximal tubule.
what is also reabsorbed in the collecting duct?
Urea
_______ and _________ reabsorbed throughout tubules.
urea and ammonia
-greater surface area
-High level of reabsorption. 70% of water, 100% of amino acids and glucose. Also Na, K, Cl. (Na-glucose linked transporters) and ca+, Mg+, bicarbonates and vitamins
PCT
-water permeable
-The descending and ascending loops (DL, AL) work together to form concentration gradient allowing for filtrate to become concentrated
DLH, thin
Impermeable to water but active reabsorption of Na, Cl, Ca, Mg
ALH (TAL)
Final salt (electrolyte), water balance under control of antidiuretic hormone (ADH), site of acid base equilibrium.
DCT
Final water reabsorption and concentration of urine. Under control of ADH. Moves urine into the renal pelvis.
CD or CT
the proximal tubule is mostly ______transport.
active
(glucose, amino acids, proteins, most ions, uric acid).
The proximal tubule reabsorbs about ___ % of water.
66
the process of using energy to generate anosmotic gradientthat enables you to reabsorb water from the tubular fluid and produce concentrated urine.
-in the medulla and loop of Henle
Countercurrent multiplication
what are four renal concentrating mechanisms?
- Proximal tubule reabsorption
- Countercurrent multiplication
- Aldosterone
- absorption of water in the distal portion (collecting ducts) regulated by antidiuretic hormone (ADH)
Descending loop of Henle (thin DL) – ______water permeability, ______ion, urea permeability
high, low
Ascending LH (Thick AL) – impermeable to _______, permeable to ______.
water, ions
Countercurrent exchange
Needed solutes have more time to diffuse back into the interstitial fluid, which maintains the solute concentration gradient in the medulla.
-NaCl leaves AL and moves into interstitial space, but H2O retained (gets hypotonic).
-The solutes and water even out in concentration as water leaves the DL. Ions pumped into DL. Gets hypertonic as it moves down DL.
-As urine is continuously produced, more water gets out of DL (repeats) and pushes existing fluid around loop. Absorbed water is returned to the circulatory system.
Countercurrent mechanism on loop of Henle
How does urea contribute to the countercurrent mechanism?
by being transported by the descending limb of the loop of Henle to the interstitial.
what is this mechanism called?
The nephrons involved in the formation of concentrated urine extend all the way from the cortex of the kidney to the medulla and are accompanied by vasa recta. The filtrate flows into the two limbs of the Henle’s loop in the opposite directions and therefore, the flow of blood cells in vasa recta is also in the opposite directions.
coutercurrent mechanism
urea contributes to the _____________ gradient.
urea
_____ L of plasma are filtered at the glomerulus the rate of ____ ml/min.
180, 120
About _____ L becomes urine if body is normally hydrated and kidneys are unimpaired
1.4
Average adult urine daily volume of urine _________ ml.
Normal total urine range may be from _______ ml/24 hr.
1200-1500
600-2000
____________is an abnormal increase in the volume of urine (> 2500 ml), as in diabetes insipidus and diabetes mellitus.
Polyuria
___________ is a decrease in urinary volume, such as occurs in shock and acute nephritis. In an adult it is frequently defined as being <500 ml/24 hr or <300 ml/m2/24 hr.
Oliguria
___________ designates the complete suppression of urine formation, although in the wider sense of the term it is sometimes defined as being < 100 ml/24 h during 2 to 3 consecutive days, in spite of a high fluid intake.
Anuria
Urine consists of…
water, urea, uric acid, creatinine, excess ions and salts, and ammonia.
In 24 hours the body excretes approximately 60 g of dissolved material, half of which is ________.
urea
What products should not be in the final urine composition?
Bilirubin
Blood
Glucose
Ketone bodies
Porphyrins
Protein
Albumin Should not exceed ____mg/dL in urine.
5.4
Creatinine should be ____________ by healthy kidneys.
excreted
What are sediments that could be present in the final urine composition.
-Cells
-Casts
-Crystals
-Some of these are considered to be normal, while others are seen in various renal and metabolic disorders.
What AREA is the exclusive portion of filtration?
cortex
blood supply surrounding the tubules.
vasa recta
What is passively transported in the proximal tubule
Water, cl-, k, and urea
What is a actively transported in the proximal tubule
Mg2+, lactate, ca2+, phosphorus, AA/proteins, and glucose, citrate
67% of what is reabsorbed in the PT
Water
Almost 100% of what is reabsorbed at the proximal tubule
Glucose, lactose, AA, bicarbonate
67% of what is reabsorbed at the Proximal tubule
Water
65% of what is reabsorbed at the PT
K and Na+
What is the urethra
Where urine leave
What is the ureters
Ureters bring urine to the bladder from the kidneys.
