Chap. 24 Kidneys

Kidney Functions

1. Filter Blood to remove metabolic wastes

2. Regulate fluid and electrolyte balance

3. Regulate pH

4. Secretes renin, which influences BP

5. Regulate RBC production by erythropoietin

6. Other metabolic functions

Afferent arterioles/Efferent arterioles

Take blood to the glomerulus; take blood away

Fenestrated Capillaries

Most leaky

prevent large substances like blood from exiting

Basal Lamina

prevent substances greater than 8 nm from entering the capsular space(blocks plasma proteins)

Podocytes

substances smaller than 6-7 nm to pass

albumin is prevented from entering

GFR

125 mL/min

180 L/day

Glomerular hydrostatic pressure

BP in GC→ positive force that pushes fluid and solutes out of capillary and into capsular space

Colloid Osmotic Pressure

The desire of protiens to be surrounded by water and pull water back into capillaries by osmosis(negative force)

Capsular hydrostatic pressure

Negative- pressure with the capsule that pushes fluid and solutes back into glomerulus

Angiotensin-ll

1. Triggers the release of aldosterone( reabsorb more Na+ ions)

2. Increase thirst

3. Cause the efferent arterioles to vasoconstriction

4. Tigger the release of ADH(water reabsorption)

If maca densa cells taste too much salt in the filtrate, the GFR is too _____, and then juxtaglomerular cells signal the afferent arteriole to _____.

high; vasoconstrict

Erythoporropoetin is produced by the kidneys to:

regulate RBC production by the bone marrow

In absence of ADH, the distal tubules and collecting ducts are ______ to water

impermeable

Typical urine production in a day?

1.8 L

Which hormones directly and indirectly promote water reabsorption?

Aldosterone and ADH

Three layers of filtrate membrane from deep to superfical?

Fenestrated, basal lamina, podocytes

The myogenic mechanism acts to restore GFR by changing _____?

diameter of afferent arteriole

The reabsorption of bicarbonate ions in proximal tubules help regulate

blood pH

Statements about glomerular filtration rate(GFR)

Normal GFR is 125 mL/min

Chronic kidney disease if GFR less than/equal to 60 mL/min for 3 months

Kidney failure of GFR is less than 15 mL/min

if ADH is NOT being secreted, what type of urine is produced?

dilute urine

If GFR is too high the tubules may not have adequate time to reabsorb all the valuable nutrients from the filtrate, and the glomeruli may be damaged. If GFR is too low, metabolic wastes may not be properly filtrated from, the blood

both statements are true

The countercurrent mechanism gives the kidneys the ability to make either dilute or concentrated urine by establishing a steep concentration gradient in the renal medulla

True

Distal tubules/collecting ducts

Ac

Ascending NL

Reabsorption of salts

Renal corpuscle

Filters bloodDe

Descending NL

Reabsorption of water

Proximal tubules

Reapportion the majority of the filtrate back into the blood

Function of Tubular reabsorption

reclaims items from filtrate and returns them to the blood

Functional unit of kindey

Nephron