Urinary System

Question 1

What are metabolic waste problems?

Answer 1

potentially harmful substances to the body
-must be eliminated
ex: CO2, H2O, bile salts, nitrogenous waste

Question 2

What is the urinary system?

Answer 2

single most important route for removal of waste products
*removes nearly all soluble waste from blood
-transports soluble waste out of body
-eliminates excess water

Question 3

Parts of urinary system

Answer 3

-kidneys (2)
-ureters (2)
-urinary bladder
-urethra

Question 4

Functions of Kidney

Answer 4

production of urine to facilitate elimination of metabolic waste materials

Question 5

Kidneys help maintain homeostasis through:

Answer 5

-blood filtration: reabsorption, secretion
-fluid balance regulation
-acid base balance regulation
-production of hormones
-blood pressure regulation

Question 6

Kidney location

Answer 6

-located in dorsal abdominal area
-near lumbar vertebrae
retroperitoneal to the abdominal cavity
-surrounded by layer of perirenal fat
-right kidney more cranial than left (except pigs)

Question 7

Gross anatomy of Kidney

Answer 7

-bean shaped in most
*covered by fibrous c.t. capsule
-hilus: indented area on medial side

Question 8

Nephron

Answer 8

basic functional unit
-numbers varies with size of animal

Question 9

Nephron is composed of:

Answer 9

1. renal corpuscle
2. proximal convoluted tubule
3. loop of Henle
4. distal convoluted tubule

Question 10

Renal corpuscle

Answer 10

-located in renal cortex
-made up of glomerulus
-surrounded by Bowman’s capsule
-filters blood in first stage of urine production: glomerular filtrate

Question 11

Proximal Convoluted Tubule

Answer 11

-continuation of capsular space of Bowman’s capsule
-longest part of nephron
*reabsorption and secretion functions
-glomerular filtrate now called tubular filtrate

Question 12

Loop of Henle

Answer 12

-continues from PCT, descends in medulla, makes U turn then heads back into cortex
-descending wall is thinner, ascending wall becomes thicker again
-resorb water, Na+, Cl-

Question 13

Distal convoluted tubule

Answer 13

-continuation of ascending loop of Henle
-all nephrons empty into collecting ducts
(renal pelvis)

Question 14

Collecting ducts

Answer 14

primary site of ADH action and regulation of potassium and acid-base balance

Question 15

Nerve supply to Kidneys

Answer 15

-sympathetic portion of autonomic ns
-not essential for function
-sympathetic stimulation causes vasoconstriction or renal vessels= *temporarily decreases urine function

Question 16

Blood supply to the kidney

Answer 16

comes from renal artery, enters at hilus
-subdivides to become a series of afferent glomerular arterioles

Question 17

2. Afferent glomerular arterioles

Answer 17

carry blood to renal corpuscle

Question 18

3. Glomerular capillaries

Answer 18

filter some plasma out of the blood: glomerular filtrate
-then vessels turn into efferent glomerular arterioles

Question 19

4. Peritubular capillaries

Answer 19

O2 transfer to cells of nephron

Question 20

5. Tubular

Answer 20

reabsorption and tubular secretion occur at this level

Question 21

Mechanisms of Renal Action

Answer 21

1. filtration of blood
2. reabsorption of useful substances - back into bloodstream
3. secretion of waste products - from the blood

Question 22

Filtration of the blood

Answer 22

-occurs in renal corpuscle

Question 23

High blood pressure in glomerular capillaries forces

Answer 23

some plasma into capsular space of Bowman’s capsule
-fenestrations in capillary endothelium
-glomerular filtrate formed (similar to plasma but no protein)

Question 24

Glomerular Filtration Rate

Answer 24

-how fast plasma is filtered as it passes through the glomerulus
-depends on rate of blood flow to kidney

Question 25

Reabsorption

Answer 25

useful substances leave tubules of nephron and enter into blood of peritubular capillaries ex: Na, K+, glucose, amino acids, etc

Question 26

Sodium reabsorption

Answer 26

-sodium actively pumped out of cell into interstitial fluid, where it moves into peritubular capillaries -in tubular filtrate attaches to carrier protein *also reabsorbed in ascending loop of Henle and DCT

Question 27

Secretion

Answer 27

primarily in DCT ex: H+, K+, ammonia

Question 28

Urine Volume Regulation

Answer 28

urine volume is determined by amount of water contained in tubular filtrate when it reaches the renal pelvis

Question 29

What is urine volume controlled by

Answer 29

actions of 2 hormones: 1. antidiuretic hormone (ADH) - prevents loss of water 2. aldosterone

Question 30

Angiotensin II

Answer 30

causes arterial constriction to increase blood pressure and stimulates release of aldosterone

Question 31

Ureters

Answer 31

-continuation of the renal pelvis -move urine from kidneys to bladder -each ureter leaves its kidney at the hilus -composed of 3 layers

Question 32

How do ureters enter the bladder

Answer 32

at an oblique angle -openings collapse when bladder is full -prevent backup of urine into ureters

Question 33

Urinary bladder

Answer 33

-stores urine as it is produced -release urine periodically from body - 2 parts: muscular sac and neck

Question 34

What muscle contracts to expel urine?

Answer 34

detrusor muscle

Question 35

Urination Step 1

Answer 35

urine accumulation: -bladder accumulates urine -stretch receptors in bladder wall are activated -pressure of filling bladder reaches certain trigger point

Question 36

Urination Step 2

Answer 36

muscle contraction: -spinal reflex is activated -motor impulse sent to detrusor muscle -smooth muscle in bladder wall contracts -bladder emptied if animal is not house broken

Question 37

Urination Step 3

Answer 37

sphincter muscle control: -voluntary control of sphincter around heck of bladder offer temporary control of urination -eventually it relaxes, urine is released

Question 38

Urethra

Answer 38

-continuation of neck of bladder -carries urine from bladder to external environment -runs through pelvic canal