BIPN 100 Lecture Notes - Lecture 26: Macula Densa, Vascular Resistance, Arteriole

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browngnu790

28 Jun 2018

School

UCSD

Department

Biology/Animal Physiol & Neurosc

Course

BIPN 100

Professor

Catalina Reyes Gonzales

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BIPN100 Lecture 26 Notes 6/9/18

- Osmolarity changes through the

nephron

oDescending limb on loop of

Henle contains aquaporin 1.

There’s a driving force for water

to exit nephron, so water is

reabsorbed (from nephron to

interstitial fluid)

oNKCCs (Na+ K+ Cl- channels)

located on ascending limb of

loop of Henle. Due to Na+/K+

pump, there’s a driving force for

Na+ to enter, so Na+ enters, pulling 1K+ and 2Cl- in with it. Through leaked channels, the

ions exit the nephron and enter the interstitial fluid for reabsorption. Some ions are

reabsorbed, but some stay in the medulla to maintain the osmotic gradient

oEntering the distal tubule, fluid is hyposmotic at 100 mOsM. In distal tubule and

collecting duct, hormones can control reabsorption of water and solutes

If you’re dehydrated, want to recycle water. Collecting duct can contain aquaporins

on the apical membrane, under the influence of the posterior pituitary hormone

vasopressin (anti diuretic hormone, ADH)

Membrane recycling: When you need to conserve

water, hypothalamus signals posterior pituitary

gland to release vasopressin into bloodstream.

Travels to collecting duct and binds to vasopressin

2 receptor (V2; membrane receptor) to activate Gs

transduction pathway. PKA phosphorylates

storage vesicles that contain aquaporin 2,

signaling them to fuse with apical membrane of

collecting duct. Now water can move through

pore from lumen -> cell -> interstitial fluid -> peritubular capillaries -> reabsorbed

When vasopressin is active, you have concentrated urine. When vasopressin isn’t

active, water isn’t reabsorbed in the collecting duct, so you have dilute urine

oControl of vasopressin (ADH)

Increased osmolarity and low blood pressure/low blood volume causes vasopressin

to be released

These stimuli activate 2 different pathways

In collecting duct, binds to V2 receptors to activate Gs pathway. This increases

water permeability, so water can be reabsorbed. This increases blood volume

(and blood pressure) and decreases osmolarity

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Document Summary

Osmolarity changes through the nephron: descending limb on loop of. There"s a driving force for water to exit nephron, so water is reabsorbed (from nephron to interstitial fluid: nkccs (na+ k+ cl- channels) located on ascending limb of loop of henle. Due to na+/k+ pump, there"s a driving force for. Na+ to enter, so na+ enters, pulling 1k+ and 2cl- in with it. Through leaked channels, the ions exit the nephron and enter the interstitial fluid for reabsorption. Some ions are reabsorbed, but some stay in the medulla to maintain the osmotic gradient: entering the distal tubule, fluid is hyposmotic at 100 mosm. In distal tubule and collecting duct, hormones can control reabsorption of water and solutes. Collecting duct can contain aquaporins on the apical membrane, under the influence of the posterior pituitary hormone vasopressin (anti diuretic hormone, adh) Membrane recycling: when you need to conserve water, hypothalamus signals posterior pituitary gland to release vasopressin into bloodstream.

Related Questions

1. Which of the following vessels, if stimulated to vasoconstrict, would cause increased filtration in the glomerular capillaries?

(a) Afferent arterioleâ(c) Efferent arteriole

(b) Vasa rectaâ(d) Peritubular capillaries

2. Which of the following CORRECTLY describes the flow of filtrate through the renal tubule?

(a) Glomerulus Ã Distal convoluted tubule Ã Ascending limb of nephron loop Ã Descending limb of nephron loop Ã Proximal convoluted tubule Ã Collecting duct

(b) Glomerulus Ã Proximal convoluted tubule Ã Descending limb of nephron loop Ã Ascending limb of nephron loop Ã Distal convoluted tubule Ã Collecting duct

(c) Glomerulus Ã Proximal convoluted tubule Ã Ascending limb of nephron loop Ã Descending limb of nephron loop Ã Distal convoluted tubule Ã Collecting duct

(d) Glomerulus Ã Distal convoluted tubule Ã Descending limb of nephron loop Ã Ascending limb of nephron loop Ã Proximal convoluted tubule Ã Collecting duct

3. Tubular ______________ occurs when certain substances (i.e. ions, drugs) are removed from the bloodstream and placed back into the renal tubule.

(a) Eliminationâ(c) Secretion

(b) Reabsorptionâ(d) Filtration

4. Which of the following is TRUE about the reabsorption process in the proximal convoluted tubule?

(a) Na + ions are actively transported out of the tubule and into the peritubular capillaries

(b) Negatively charged ions (e.g. chloride) are transported out of the tubule in response to the movement of sodium

(d) All of the above

5. Which of the following statements is FALSE about the glomerulus and the processes that occur there?

(a) Capsular hydrostatic pressure refers to the pressure of fluid pressing on the capsule and opposes filtration

(b) Net filtration pressure in the glomerulus is the difference between forces favoring filtration and forces opposing filtration

(d) Vasoconstriction of the efferent arteriole lowers glomerular filtration rate

6. The descending limb of the nephron loop is impermeable to water while the ascending limb of the nephron is permeable to water.

(a) Trueâ(b) False

7. Which of the following vessels takes blood out of the renal corpuscle and returns it to the bloodstream?

(a) Peritubular capillary systemâ(c) Vasa recta

(b) Efferent arterioleâ(d) Afferent arteriole

8. Under the influence of ADH, the ___________________ and the _________________ become permeable to water and water is reabsorbed.

(a) Proximal convoluted tubule, Nephron loop

(b) Distal convoluted tubule, Nephron loop

(d) Distal convoluted tubule, Collecting duct

9. What is the name of the region inside the bladder bounded by the two uretal openings and the urethra?

(a) Trigoneâ(c) Mucous layer

(b) Detrusor muscleâ(d) Transitional epithelium

10. During the accumulation of urine, the bladder distends, allowing stretch receptors in the transitional epithelium to be stimulated.

(a) Trueâ(b) False

lemongoat70

1) A drop of urine would follow this path

a) renal pyramid/major calyx/minor calyx/renal pelvis/ureter

b) minor calyx/major calyx/renal pyramid/renal pelvis/ureter

c) renal pelvis/minor calyx/major calyx/renal pyramid/ureter

d) renal pyramid/minor calyx/major calyx/renal pelvis/ureter

2) The production of filtrate starts at

a) Loop of Henle

b) capsular space

c) distal convoluted tubule

d) proximal convoluted tubule

3) Major reabsorption of water happens by ____at the _____

a) contransport, distal convoluted tubules

b) Cl- shift, nephron loop

c) countercurrent, nephron loop

d) countercurrent, ureter

4) Angiotensin II causes production of ____to increase Na + reabsorption in the _________

a) renin; collecting duct

b) aldosterone; PCT

c) ADH; nephron loop

d) aldosterone; collecting duct

5) Most of the reabsorbed compounds from the filtrate end up in the

a) peritubular capillary

b) urine

c) nephron loop

d) DCT

6) Reabsorption of urea happens by

a) transcellular movement

b) by paracellular movement

c) by cotransport with glucose

d) by HCO3- movement

7) Transport Maximum, in urinary system terms, refers to

a) proteins performing âtransportâ out of the filtrate at maximum rate

b) the reason why a diabetic produces large volumes of diluted urine

c) excess filtrate components being urinated out of the body

d) All choices are correct

8) Urine does not drop below pH 4.5 because

a) proteins that move H+ into filtrate stop working when too much H+ builds up in filtrate

b) proteins in urine neutralize acid

c) H+ are always buffered

d) the buffering system in urine does not run out

9) Hyperkalemia will

a) activate adrenal cells to secrete aldosterone

b) can stop the heart

c) No choices are correct

d) cause reduced excitability of neurons

e) All choices are correct

10)In your body, chloride (Cl-) can be found in its highest concentration in

a) extracellular fluid

b) intracellular fluid

c) Neither choice is correct

11) Diuretic abuse leads to

a) All choices are correct

b) two choices are correct

c) No choice is correct

d) dehydration

e) athletes being accused of doping

f) hypotonic hydration

12) Long diffusion distance, low blood pressure, and impaired circulation are the result of

a) hypernatremia

b) edema

c) hyperkalemia

d) water toxicity

13) In males FSH is under feedback control by _____ and is down regulated when _________reaches high concentrations

a) inhibin, testosterone/sperm #s

b) testosterone, inhibin/sustentocyte #s

c) ADH, inhibin/sustentocyte #s

d) LH, testosterone/sperm #s

14) Testosterone production is done by ____-cells

a) posterior pituitary

b ) interstitial endocrine

c) anterior pituitary

d) sustentocytes

15) Upon _____of estrogen/progesterone, the ____phase of the uterine cycle begins

a) increase; menstrual

b) decrease; menstrual

c) increase; proliferative

d) decrease; secretory

16) Progesterone

a) All choices are correct

b) is low in the luteal phase

c) No choices are correct

d) raises in the follicular phase

e) is high along with estrogen during the follicular phase

17) Which nephron is most responsible for urine concentration?

a) cortical nephrons

b) Juxtamedullary nephrons

c) Neither

carminesalmon877

1) Which is NOT characteristic of metabolism during theabsorptive state?

a) oxidation of about 50% of the glucose absorbed from a typicalmeal

b) conversion of glucose to glycogen in hepatocytes

c) gluconeogenesis using amino acids

d) glucose not picked up by the liver is converted intotriglycerides.

e) deamination of absorbed amino acids which enteredhepatocytes.

2) In the Krebs cycle, an oxidation-reduction reaction is likelycoupled with a substrate-level phosphorylation. True or False?

3) Glycolysis is an example of oxidative phosphorylation. trueor false?

4)Which of the following statements is incorrect?

a)In the proximal convoluted tubule, sodium ions are reabsorbedthrough the apical membrane by the Na⁺ -glucosesymporters and Na⁺ /H⁺ antiporters

b) In the loop of Henle, Na⁺-K⁺-2Cl^- Symporters reclaim sodium, potassiumand chloride from fluid in the tubule lumen.

c)In the distal convoluted tubule, sodium resorption is mainlyby osmosis

d) In the collecting duct, principle cells absorb sodium.

5) Which of the following might indicated abnormal kidneyfunction?

a)creatinine clearance less than 120-140 mL/min

b)serum creatinine less than 1.5 mg/dL (135 mmol/liter)

c) glucose in the urine

d) creatinine clearance less than 120-140 mL/min and serumcreatinine less than 1.5 mg/dL (135 mmol/liter) are bothcorrect

e)creatinine clearance less than 120-140 mL/min, serumcreatinine less than 1.5 mg/dL (135 mmol/liter), and glucose in theurine are all correct

6) ACE inhibitors can lower blood pressure because inhibitingACE

a) stops the secretion of renin

b) prevents the formation of angiotensin I

c) prevents the formation of angiotensin II

d)increases the secretion of aldosterone

e)prevents norepinephrine from binding alpha 1 receptors onblood vessels

7) Which of the following statements is TRUE?
1. Hydrogen ions are secreted by Na⁺/H⁺antiporters in the proximal tubules.
2. H⁺ATPases (proton pumps) in the collecting ductssecrete hydrogen ions.
3. Cl^-/HCO₃^- antiporters help withhydrogen ion reabsorption.

8) Which of the following is mismatched?

a)Sodium ions ï¿½ Level is controlled by aldosterone, antidiuretichormone, and atrial natriuretic.

b) Chloride ions ï¿½ Level is controlled by chloride ion leakagechannels and antiporters.

c) Potassium ions ï¿½ Level is controlled by aldosterone.

d) Bicarbonate ions ï¿½ Level is controlled mainly by kidneys.

e) Calcium ions ï¿½ Level is regulated by osmosis.

9) Which of the following statements is correct?

a) In the menstrual phase, follicle stimulating hormonestimulates development of secondary follicles in the ovaries andprostaglandins cause loss of the stratum functionalis.

b)In the preovulatory phase, secondary follicles start tosecrete estrogens and inhibin. One becomes a dominant follicle andsecretes estrogens and inhibin causing decreased FSH secretionleading to atresia of less developed follicles. In the uterus, theendometrium undergoes repair under the influence of estrogens.

c)In ovulation, release of luteinizing hormone causes release ofthe secondary oocyte.

d) In the postovulatory phase, progesterone and estrogens aresecreted by the corpus luteum promote thickening of the endometriumpreparing for implantation. If no pregnancy occurs, progesteroneand estrogen levels drop and menstruation occurs.

e) all of these statements are correct

10)The secretory phase of the uterine cycle is associatedwith

a)increased secretion of progesterone and formation of thecorpus albicans.

b)increased secretion of progesterone and formation of thecorpus luteum.

c) increased secretion of luteinizing hormone and rupture of themature follicle.

d)increased secretion of estrogen and maturation of thesecondary follicle

e) increased secretion of follicle stimulating hormone andovulation.

11) Filtered fluid leaving the glomerular capillariesIMMEDIATELY enters the

a) glormerulus

b) proximal convulted tubule

c) collecting duct

d) glomerular capsule

e) loop of henle

12)Which correctly associates structure with tissue type?

a)PCT: simple cuboidal epithelium consisting of principle cellsand intercalated cells

b)descending limb and thin ascending limb of nephron loop:simple squamous epithelial cells

c) thick ascending limb of nephron loop: simple cuboidalepithelial cells with prominent brush borders of microvilli

d) DCT: simple cuboidal to low columnar epithelial cells

e) collecting duct: stratified cuboidal epithelial cells

13) Regulation of the volume and osmolarity of body fluidsoccurs first in the

a) proximal convoluted tubules.

b) distal convoluted tubules.

c) loop of Henle.

d) glomerular capsule.

e) collecting ducts.

14) Which is NOT True about podocytes?

a) their pedicels form filtration slits

b) they make up the parietal layer of the glomerular capsule

c) they are modified simple squamous epithelial cells

d)all of these choices statements about podocytes are true

15) In the process of forming concentrated urine, symporters inthe loop of Henle cause sodium ions and chloride ions to build upin the renal medulla helping to form the osmotic gradient. ADHincreases reabsorption of water by principal cells in thecollecting ducts.

True or False?

viridianmallard359

BIPN 100 Lecture Notes - Lecture 26: Macula Densa, Vascular Resistance, Arteriole

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