Chapter 20 Urinology

Question 1

Renal means?

Answer 1

Renal: Of, relating to, or in the region of the kidneys

Question 2

What are the four components of the Urinary system?

Answer 2

1. Kidney
2. Ureter
3. Urinary bladder
4. Urethra

Question 3

What is filtrate?

Answer 3

Fluid filtered from blood that enters nephron

Question 4

What are the two regions of the Kidney?

Answer 4

1. Outer renal cortex
2. Inner medulla with pyramids

Question 5

What is the pathway for drainage of filtrate?

Answer 5

Within the Inner medulla there are pyramids which drain into a minor calyx to a major calyx then the renal pelvis.

Question 6

Where is urine made? What is the pathway of Urine?

Answer 6

1. Kidney
2. a. Pools in renal pelvis
   b. Down ureter
   c. Into urinary bladder
   d. Exits body through urethra

Question 7

What are the sphicnters surrounding the urethra? What muscle is each one made of?

Answer 7

1. Internal urethral sphincter
   - smooth muscle
2. External urethral sphincter
   - skeletal muscle

Question 8

How many nephrons are in each kidney? Where does filtration occur?

Answer 8

1. Each kidney has a million microscpic nephrons
2. Filtration occurs in the renal corpuscle of the cortex

Question 9

Is The Loop of Hendle part of the renal cortex or medulla? What is urine formed from? What is the pathway of filtrate into urine?* *

Answer 9

1. The loop of helde dips down from the cortex into the medulla
2. Urine is formed from filtrate
3. Bowman’s capsule to proximal convoluted tubule to loop of hendle to distal convoluted tubule to collecting duct

Question 10

What are the functions of the kidney? How does it do this?

Answer 10

1. Regulates the extracellular fluid in the body
   a. blood volume
   b. ions
   c. pH
2. Removal of waste products from blood and excretion from body as urine
   a. filtration
   b. reabsorption
   d. secretion
   e. excretion

Question 11

What are the functions of the nephron?

Answer 11

1. filtration
2. reabsorption
3. secretion
4. excretion

Question 12

Where does filtration occur? What is the structure of it’s capillaries?

Answer 12

1. Filtration occurs in the glomerular corpuscle where fluid if filtered out of the blood and into nephron
2. The capillaries of the glomerular corpuscle are fenestrated
   - the large pores allows water and solutes to leave but not blood cells and plasma proteins

Question 13

What does the glomerular **filtration rate measure? At what rate does it filter?

Answer 13

1. Glormeruler filtration rate: volume of fluid produced by both kidneys that filters into the renal corpuscle per unit time
2. Average is 180 L/day or 125 mL/min

Question 14

What are the three factors that influence net filtration in the Glomerular? How do they effect Filtrate?

Answer 14

1. Bp in glomerulus
   - Cuases pressure to filter out of capillaries into nephron
2. Blood proteins in capillaries
   - causes fluid to be pulled in the capilaries by osmosis
3. Fluid in Bowman’s capsule
   - opposes filtration in cappilaries and pushes back in

Question 15

What are the two types of absorption? WHat membranes do they cross?

Answer 15

1. Active or passive
2. Apical and basolateral membrane

Question 16

What are the principles of the reabsorption of solutes?

Answer 16

1. Na+ is reabsorbed by active transport
2. Electrochemical gradient drives anion reabsoprtion
3. Water moves by osmosis following solute reabsorption
   - concentrations of other solutes increase as fluid volume in lumen increase
4. Permeable solutes are reabsorbed by diffusion through membrane transporters or by paracelluler pathway (junctions between epithelial cells)

Question 17

How much filtered water is excreted as urine?

Answer 17

Of the 180L of water filtered, only 1-2L is excreted as urine

Question 18

What percentage of plasma is filtered as it passes the glomerulus? What percentage is excreted? Describe this process.

Answer 18

1. Only 20% of the plasma is filtered
2. Less than 1% is filtered
3. a. 100% of the plasma volume enters the afferent arteriole
   b. 80% of the plasma passes through to efferent arteriole while the other 20% filters out in the glomerulus
   c. Less then 19% of filtrate is reabsorbed
   d. The original 80% that passed unfiltered as well as the >19% that was reabsorbed equals >99% of plasma entering the kidney that returns to the systemic circulation
   e. the remaining <1% is excreted to the external environment

Question 19

What does the proximal convoluted tubule reabsorb? What are the physical means of reabsorbing

Answer 19

1. The PCT reabsorbs most Na+ and water. The PCT completely reabsorbs glucose and amino acids by:
2. a. 2nd active transport with Na+ into cell
   b. 1st active transport of Na+ out of cell basolateral membrane
   c. **facilitated diffusion **
   d. simple diffusion

Question 20

How is salt pumped into interstitial fluid via the ascending loop of henle?

Answer 20

• Na+ is reabsorbed down its gradient from filtrate into tubule cells with 2nd active transport of CL- and K+
• Na+ is moved into interstitial space by Na+ and K+ pumps
• Because the cellls of the loops of hendle are not permeable to water, the active reabsoprtion of ions in this region creates a dilute filtrate.

Question 21

Where does the countercurrent exchange system occur? Which limb is permeabel to either water or salt?

Answer 21

1. Countercurrent exchange system occurs in the medulla as it uses juxtamedullary nephrons and vasa recta capillaries.
2. a. Descending limb is permeable to water only
   b. Ascending limb is permeable to **salt **

Question 22

What is the countercurrent exchange between in the vasa recta?

Answer 22

• Filtrate entering the descending limbb becomes progressively more concentrated as it looses water
• Blood in the vasa recta removes water leaving the loop og henle
• The ascending limb pumps out Na+, K+ and Cl_ and filtrate becomes hyposmotic

Question 23

What is secretion?

Answer 23

• The active process using membrane proteins to transfer molecules from blood/ECF filtrae in lumen of nephron
• penicilin

Question 24

What is excretion? What is it composed of?

Answer 24

1. Excretion is the elimination of material from the body
2. _ filtration __- reabsorption + secr__etion_ = excretion

Question 25

slide # 19

Question 26

What is the **anti-diuretic hormone**? Where is it _produced_? What is another name for it?

Answer 26

1. ADH causes the body to retain water 2. *Produced* *by* neurons of the **hypothalamus** and *secreted* *by* **posterior pituitary gland ** 3. Also called **vasopressin**

Question 27

What is the role of **aquaporins**?

Answer 27

Aquaporins in the _collecting duct_ cause *water* to be **reabsorbed**.

Question 28

What happens when **ADH** _binds to receptors_ on the **collecting duct**?

Answer 28

1. Causes *vesicles* with *aquaporin channels* to _fuse_ to the *plasma membrane* 2. *Water channels are removed* without ADH

Question 29

What is **Aldosterone**? What are its _functions_?

Answer 29

1. It is a steroid hormone secreted by adrenal gland 2. a. regulates **Na+ absorption** in _distal convoluted tubule_ and _collecting duct_ b. increases action of _Na+,K+, ATPase_ in epithelial cells

Question 30

What is **ANP**? When is it _released_?

Answer 30

1. **Atrial natriuretic peptide**: *peptide hormone* produced by specialized *myocardial cells* in the wall of atria. 2. Increases **Na+ and water excretion**

Question 31

How does the kidney **autoregulate** _glomeruler filtration rate_? And _renal blood flow_?

Answer 31

1. **GFR** is maintained despite BP fluctuations due to **tubuloglomerular feedback**: - _macula densa cells_ sense rise in *water and Na+* which signals increased BP 2. **Renal blood flow** is regulated through **mypogenic constriction**: - _smooth muscles__ _in arterioles sense BP

Question 32

What is the **relation** between _fluid_ and _ion_ levels? What organ _regulates fluid_?

Answer 32

1. Fluid balance implies a balance of ions 2. **Kidneys** regulate fluid balance by either _loosing or gaining fluid_ at different rates as needed.

Question 33

Since the healthy range of **plasma protein** is narrow, what happens when it is _below or above that range_?

Answer 33

1. _Hypokalemia = below_. - *muscle weakness and failure* of respiratory muscles and the heart 2. _Hyperkalemia = above_ - *heart arrythmias*

Question 34

What role does: **Na+, water, K+, Ca2+, H+, HCO3-, and mass balance **play?

Answer 34

1. **Na+: ECF volume and osmolarity** 2. K+: cardiac and muscle function 3. **Ca2+: exocytosis, muscle contractions** 4. **H+ and HCO3-: pH balance** 5. **Body mass: excretion routes**: kidney, feces, sweat, and lungs

Question 35

What is the amount of **water gained** in the body? WHat is the amount of **water lost**?

Answer 35

1. a. **2.2L/day** of water is gained from **food and drink** b. **0.3L/day** is produced from **metabolism** c. This _totals_ about **2.5L/day** 2. a. **0.9L/day** as insensible water loss through **skin and lungs** b. **1.5L/day** is lost through **urine** c. **0.1L/day** is lost through **feces** d. This _totals_ **2.5L/day**

Question 36

What is the response to **decreased** _blood pressure and volume_?

Answer 36

1. **Stimulus**: *decreased* _blood volume and pressure_ 2. **Sensor**: _volume receptors in atria_ and _carotid aortic barorecetors_ 3. **Signal**: trigger homeostatic reflexes 4. **Targets**: _Cardiovascular system, behavior, kidneys_ 5. **Tissue response**: a. *cardiovascular system*: _increases cardiac output, vasoconstriction_ b. *behavior*: thirst cuases increased _water intake_ which _increases ECF and IC__F_ volume 6. **Systemic response**: a. *cardiovascular system and behavior*: _increase BP_ b. *Kidneys*: *conserve H20* to minimize further volume loss

Question 37

What is the _normal pH_ of *plasma*? HWat happens to **proteins** in regard to pH? What happens when the **pH levels** are _too high or low_?

Answer 37

1. Normal pH of plasma is **7.38-7.42** 2. H+ changes can **alter the 3-D structure** of proteins 3. Abnormal pH effects the nervous system by: a. **Acidosis**(low): neurons are less excitable; _CNS depression_ b. **Alkalosis**(high): _hyperexcitable_

Question 38

How does pH maintain **homeostasis**? How does each effect pH?

Answer 38

1. **Buffers** a. protiens, phosphate ions, and hemoglobin b. *most buffers in the body combine with H+* 2. **Ventilation** - increases to *remove CO2* 3. **Renal regulation** a. directly *excrete or reabsorb H+* b. indirectly by rate of *HCO3- reabsorbed or excreted*

Question 39

How does the kidney compensate for **acidosis**?

Answer 39

* **The kidney secretes H+** which is buffered in the urine by *ammonia and phosphate ions* * It **reabsorbs bicarbonate** to act as a buffer