Lecture 10 Study Guide

Question 1

Know the anatomy of the kidney, including the nephron.

Answer 1

Kidney:
Gross Structure
1) Renal (fibrous) capsule- dense fibrous tissue capsule that covers or surrounds the kidney outside the kidney.

2) Renal cortex-white outer portion layer inside of entire kidney.

3)Renal medulla-inner portion of kidney.

4)Renal pyramids-where nephrons are.

5)Renal pelvis
6)Major calyces-form together with minor calyces to form the renal pelvis.

7)Minor calyces-form together with major calyces to form the renal pelvis.

Nephron:
-Functional unit of the kidney

Structure of nephron:
1) Renal corpuscle:
-Glomerulus-aka
glomerulus
capillaries.

-Bowman’s
capsule-tough fibrous ball like structure that has fluid and glomerular capillaries in it.

2) Renal tubule
-Proximal
convoluted
tubule
-Descending
loop of Henle
-Ascending loop
of Henle
-Distal
convoluted
tubule
-Collecting duct

Question 2

Know the pathway for urine formation and elimination, starting with Bowman’s capsule and ending with the urethra.

Answer 2

-Starts in Bowman’s capsule

Pathway:
-Proximal convoluted tubule
-Loop of Henle (descending loop of Henle and ascending loop of Henle)
-Distal convoluted tube tubule
-Collecting Duct
-Minor cayces
-Major cayces
-Renal pelvis
-Ureter
-Urinary Bladder
-Urethra
-Outside
environment

Question 3

Know the functions of the urinary system.

Answer 3

-Excretion (of waste)
-Elimination (of waste in urine)
-Homeostatic Regulation of Blood Volume
-Maintenance of fluid and electrolyte balance
-Secretion of erythropoietin (hormone) that helps stimulate the production of red blood cells.

Question 4

Describe the events that will occur if the body loses 1% or more of its normal fluids.

Answer 4

There will be an increase in osmotic pressure in the extracellular fluid.

Question 5

Know the parts of the juxtaglomerular apparatus and describe how it works.

Answer 5

1) Mascula Densa:
-cells in the distal convoluted tubule in contact with afferent arteriole. They are in contact with juxtaglomerular cells.

-The mascula densa cells in the J.A. acts as a sensor for us to detect the concentration of solutes once the urine gets to the distal convoluted tube. Like if we need more sodium or water or do we need to put it back or get rid of them in the collecting duct. The mascula densa cells then communicates to the rest of the nephrons, collecting duct, parts of the brain, and hypothalamus that we need to reabsorb more water, sodium, and calcium or get rid of more water. Then by the time the urine is moving from the distal convoluted tube into the collecting duct, the body can then make changes to the walls of collecting ducts that will allow water in and out.

2) Juxtaglomerular cells:
-smooth muscle cells in afferent arteriole. Sense the pressure inside afferent arteriole.

-The juxtaglomerular cells’s job is to sense the pressure inside the afferent arteriole.

Question 6

What hormone is secreted by the kidney in response to a low level of red blood cells?

Answer 6

Erythropoietin (EPO)

Question 7

Describe the anatomy of the glomerulus and Bowman’s capsule.

Answer 7

Nephron:
-Functional unit of the kidney

Structure:
1) Renal corpuscle:
-Glomerulus-aka
glomerulus
capillaries.

-Bowman’s
capsule-tough fibrous ball like structure that has fluid and glomerular capillaries in it.

2) Renal tubule
-Proximal
convoluted
tubule
-Descending
loop of Henle
-Ascending loop
of Henle
-Distal
convoluted
tubule
-Collecting duct

Question 8

Know the definitions of and what occurs in the three steps of urine formation:

Answer 8

a. Glomerular Filtration:

-Filtrate from blood collected in Bowman’s capsule

-Filtration due to hydrostatic pressure

-Produces about 125ml/minute of liquid but most is reabsorbed back in our body. We don’t pee it all out. 99% gets reabsorbed back in our body.

b. Tubular reabsorption:

-Process of substance transport from glomerular filtrate to blood in the peritubular capillaries

-Most reabsorption occurs in the proximal convoluted tubules through active transport

-Water is reabsorbed by osmosis

-Substances remaining in filtrate become concentrated as water is reabsorbed.

Reabsorbed Substances:

Glucose
Amino acids
Water
Ions
Other substances

c. Tubular secretion:

-Process by which substances are transported from the blood in the peritubular capillaries in the distal convoluted tubules

-Helps maintain ion concentrations in blood

Question 9

Trace blood through the kidney, starting with the aorta and ending with the inferior vena cava.

Answer 9

Arterial Renal (Renal Artery) Blood Flow:
-Aorta
-Renal artery
-Interlobar arteries
-Arciform arteries
-Interlobular arteries
-Afferent arteriole
-Glomerular capillaries
-Efferent arteriole
-Peritubular capillaries

Venous Renal (Renal Vein) Blood Flow:

-Interlobular veins
-Arciform veins
-Interlobar veins
-Renal vein
-Inferior vena cava

Question 10

What is a hilus?

Answer 10

Area inside renal pelvises where the ureter exits the renal pelvis area.

Question 11

What are peritubular capillaries?

Answer 11

second capillary bed of the renal portal system; surround the proximal and distal convoluted tubules; associated with the vasa recta

Question 12

What is the function of anti-diuretic hormone and what role does it play in fluid balance?

Answer 12

When we drink too much water, the secretion of ADH hormone slows down or we may not secrete any more ADH. When ADH is not present, the walls of the collecting duct becomes impermeable and water can’t get through to leave the collecting and go back into the kidney tissue. All of that water will stay in the renal tubule to be eliminated.

In absence of ADH hormone, we diurese- to eliminate excess fluid. (when we are overhydrated)

When ADH is present we keep water (not in excess) for our body and allow water to leave collecting ducts to be picked back up in our body to be used. (when we are dehydrating).

Question 13

Know the anatomy of the urethra and the urinary bladder.

Answer 13

Urethra:
-Longer in males than females
-Carries urine from the urinary bladder to the outside environment.

Bladder:

-Hollow distensible organ
-Lined by transitional epithelium
-Detrusor muscle
-Functions for urine storage

Question 14

Describe how constriction/dilation of afferent and efferent arterioles in the kidney can cause in increase/decrease in glomerular filtration rate.

Answer 14

Our body wants to get rid of more water by increasing GFR:
1)Get rid rid of water in the tubules of the nephrons and keep some water.

2) Increase GFR, by increasing the pressure that inside of the glomerulus capillaries.

3)Our body can increase blood flow by increasing the HR through vasoconstriction.

4) Our body can constrict the sphincter of the efferent arteriole to back up blood into the glomerulus to increase the pressure inside the glomerulus when it increases the pressure it pushes out more waste.

On the other hand, lets say that the GFR is too high. We will need to decrease the GFR.

1) Constrict the afferent arteriole to allow less blood flow to the glomerulus. Less blood flow means less pressure. Less pressure means less filtrate (filtrate is the waste that is collected in the Bowman’s capsule.)

This is how the J.A apparatus works. We can sense what the blood pressure is and sense if we need to increase or decrease the amount of blood pressure in the glomerulus capillaries, but we can also measure and monitor the concentration of solutes in our urine to see if we need it to be less concentrated or more concentrated and those changes can be made in the collecting ducts after the urine leaves the distal convoluted tubule.

Question 15

Define homeostasis.

Answer 15

tendency of our body to maintain
a stable internal environment.

electrolyte (an ion in solution) intake must equal
their output.

Question 16

Know the properties of water.

Answer 16

1) Solvent:
-Many solutes are dissolved in our body’s
water.

-Many ionic compounds (i.e. NaCl) dissociate
or break apart in water.

2) Chemical Reaction Participant:

-Dehydration (synthesis) reactions-pull water out of something. Causes two molecules to join together. An anabolic reaction..a building up.

-Hydrolysis (degradation) reactions-When we put something in water, they disassociate and break apart…a catabolic reaction..a breaking down.

-Temperature Buffer:

-absorbs and releases heat very slowly

-Cooling mechanism:

-absorbs and releases heat very slowly

-Lubricant
mucus
internal organs
joints

Question 17

Describe the following reactions:

Answer 17

A. Synthesis reactions:

-Large molecules from small molecules

Constructive (anabolic)

Endergonic

Dehydration to form the bond
A + B AB

Example:
Amino Acids TO Protein

B. Degradation reactions:

Small Molecules from Large Molecule
Destructive (catabolic)

Exergonic
Hydrolysis to break the bond

AB A + B

Example:
Digestion of protein to amino acids

Question 18

Know how salts ionize.

Answer 18

-Dissociate Into Ions in Water (Ionization)

-Form Electrolytes

NaCl in Water Na+ + Cl-

Question 19

Know what an electrolyte is.

Answer 19

-An ion in solution.

-maintained within a very narrow range in our blood and tissues.

-Needed for muscle contraction, nerve impulses, etc.

-Na+, K+, Cl-, Ca+, PO4-; HCO3-

Question 20

Explain what happens to acids and bases when you add water to them.

Answer 20

Acids:
Ionize in Water to Form:
-Hydrogen Ion
-Anion

Example:
HCl +H2O=
H+ + Cl-

Bases:
Ionize in Water to Form:
-Hydroxyl Anion
-Cation

Example:
NaOH+H2O= Na+ + OH-

Question 21

Know what pH is.

Answer 21

-Relative Concentration of Hydrogen Ions and Hydroxyl Ions in the Body

pH scale:
0 Acidic
7 Neutral
14 Basic

The lower we are on the ph scale (0) & the more hydrogen and carbon dioxide we have in our body the more acidic we will become. The higher we are on the ph scale (14)we are the more basic we are and the more alkalonic we are(alkaline). We won’t have much hydrogen ions.

We are neutral at a ph scale of 7.

Physiologic pH = 7.4

pH < 7.4 = acidosis
lethal below 7.0

pH > 7.4 = alkalosis
lethal above 7.8

Question 22

Describe how buffering systems work, specifically:

Answer 22

-Used to prevent abrupt pH changes

-Usually consist of weak acids

-Donates hydrogen ions when needed

-Accepts hydrogen ions when in excess

A. Carbonic Acid Buffering System-
As our ph increase, it means we are getting less and less hydrogen ions, the carbonic acid can then break apart into bicarbonate and hydrogen ion. This will cause our ph balance to decrease back toward the acidic area. The more hydrogen ions we have the more acidic we become. on the other hand, if our ph is decreasing because we have too much hydrogen ions, bicarbonate will pick up(hydrogen accept) addition hydrogen ions to form the very weak carbonic acid.

When pH is rising H2CO3 —–> H+ + HCO3-

When pH is falling
H2CO3 <—– H+ + HCO3-

B. Phosphate Buffering System-
-When ph is rising, hydrogen phosphate can break apart and give us hydrogen ions or phosphate anions to pick up hydrogen ions when needed.

When ph is decreasing, the hydrogen ions and phosphate ion will form together to form hydrogen phosphate to become more acidic.

Phosphate buffer system:

When pH is rising
H2PO4- —–> H+ + HPO4—

When pH is falling
H2PO4- <—– H+ + HPO4–

Question 23

Explain what hydrostatic and osmotic pressure.

Answer 23

Hydrostatic pressure:

-drives fluid out of plasma
-drives fluid into lymphatic vessels

The way that we filter waste out of our capillaries in these nephrons is through a hydrostatic pressure. These capillaries are fenestrated and have pores in them that are big enough to let some molecules out like uric acid or other waste products that we want to get rid of. The fenestrated holes are not big enough to allow RBC’s and proteins get through.

Anytime you have have fluid in something like the Bowman’s capsule, fluid is going to increase pressure on the walls of the glomerulus capillaries. That pressure causes waste to push out of fenestrated pores in capillaries into the Bowman’s capsule. (hydrostatic pressure)

Osmotic pressure:
-return of fluid to plasma
-regulates movement into and out of cells

-Concentration of filtrate to fluid (don’t use ATP).

-In Bowman’s capsule, there is filtrate which means anytime you have a solute or solvent in the form of a solution. The solution is going to have a concentration pressure (aka osmotic pressure).

A solvent-does the dissolving. (Glass of water)

A solute-gets dissolved. (sugar). Can be filtered out and catch sugar molecules or other molecules.

The right amount of blood pressure in our bodies is very important because too low blood pressure can cause our kidney to stop working and to stop filtering blood out of our kidneys. Blood vessels will try to constrict to increase the blood pressure.

Question 24

Explain how water intake and output is regulated.

Answer 24

Water intake:
-Majority of water is ingested

If the body loses more than 1% of its water:

osmoreceptors in the thirst center in hypothalamus stimulated

-triggers thirst

-drinking fluids distends the stomach

-stretch receptors send nerve impulses that inhibit the thirst center

Water output:
Urine
Feces
Skin
Lungs

Water Output Regulation:

Dehydration:
-Extra cellular fluid (ECF) becomes less concentrated

-hypothalamus detect increase in osmotic pressure

-posterior pituitary releases of ADH

-distal convoluted tubules and collecting ducts in nephrons increase water re-absorption

-urine output decreases

-osmotic pressure of ECF to normal

Water Intake Regulation:
Water excess (Overhydrated)

-ECF becomes less concentrated

-hypothalamus detect decrease

-posterior pituitary decreases release of ADH

-renal tubules decrease their water re-absorption

-urine output increases

-osmotic pressure of ECF to normal

Question 25

Explain how the following electrolytes are regulated:

Answer 25

A. Calcium:
1) calcitonin decreases calcium levels by:
-stimulating distal kidney tubules to secrete excess Ca++ into urine
-inhibiting osteoclast activity

2)Parathyroid hormone increases calcium levels by:
-stimulating kidney tubules to reabsorb Ca++ back into blood
activating osteoclasts to resorb bone matrix.

B. Sodium:
Aldosterone increases sodium re-absorption in kidney tubules

C. Potassium:
Aldosterone causes secretion (excretion) of excess potassium into the urine

Question 26

Explain the renin-angiotensisn-aldosterone system. What are the steps in that system and what is the effect of the system on fluid and electrolyte balance?

Answer 26

When BP in kidneys drops to certain level,
JG apparatus secretes renin into blood

Angiotensinogen in blood converted to angiotensin I by renin

Angiotensin I to lungs and converted to angiotensin II

Angiotensin II to adrenal cortex to stimulate secretion of aldosterone

Question 27

What is the primary function of aldosterone?

Answer 27

increase re-absorption of sodium - decrease in urine output - increase water retention

water retention - increase in blood volume

increase in blood volume - increase in blood pressure in kidney

increase in blood pressure -stops renin- angiotensin-aldosterone system

Question 28

Know the classification of simple acid-base disorders, specifically:

Answer 28

Acidemia:

A. Respiratory acidosis with compensatory metabolic alkalosis:

-If partial pressure carbon dioxide increases the blood ph level becomes more acidic and the person then develops respiratory acidosis (because carbon dioxide is a respiratory gas). The body’s bicarbonate level
[HCO3]then increases in response to an increase in pCO2. to get rid of the excess carbonic acid. This causes the person to develop respiratory acidosis with compensatory metabolic akalosis.

B. Metabolic acidosis with compensatory respiratory alkalosis:

-If the Bicarbonate level decreases(HCO3), The person develops metabolic acidosis. The partial pressure carbon dioxide (pCO2)will then decrease in response causing the person to develop metabolic acidosis with compensatory respiratory alkalosis.

Alkalemia:

C. Respiratory alkalosis with compensatory metabolic acidosis:

-If pCO2 levels decrease, the person develops respiratory alkalosis. The bicarbonate levels decrease in response and the person develops respiratory alkalosis with compensatory metabolic acidosis.

D. Metabolic alkalosis with compensatory respiratory acidosis:

-If the bicarbonate levels increase, the person develops metabolic alkalosis. the PO2 levels increase in response and the person develops metabolic alkalosis with compensatory respiratory acidosis.