Urinary System (Topic 13)

Question 1

Where do kidneys lie? (2)

Answer 1

back of the abdominal wall
- retroperitoneal

Question 2

What does the ureter do? (2)

Answer 2

transport urine from kidneys to bladder

Question 3

What does the bladder do? (2)

Answer 3

stores urine until voided from the body

Question 4

What does the urethra do? (2)

Answer 4

carries urine from the bladder tot he outside of the body

Question 5

What are the functions of the kidneys? (3)

Answer 5

• regulates water
• removes waste from blood
• gluconeogenesis
• secretes hormones (renin and calcium)

Question 6

What is a nephron? (4)

Answer 6

functional unit of kidney (forms urine)
- each kidney has 1 million nephrons

Question 7

What is the renal cortex? (4)

Answer 7

The outer portion
- contains renal corpuscles

Question 8

What is the renal medulla? (4)

Answer 8

inner portion
- Loops of Henle extend into medulla.
- Contains the medullary collecting ducts.

Question 9

What does a nephron consist of? (5)

Answer 9

• renal corpuscle
• renal tubule

Question 10

What does a renal corpuscle consist of? (5)

Answer 10

• glomerulus: tuft of capillary loops
• Bowman’s capsule: cup shaped around the glomerulus

Question 11

What are the two types of nephrons? (7)

Answer 11

• juxtamedullary
• cortical

Question 12

What is a juxtamedullary nephron? (7)

Answer 12

• long loop of henle
• concentration of urine
• found at the border between cortex and medulla
• about 15% of all nephrons

Question 13

What is a cortical nephron? (7)

Answer 13

• 85% of all nephrons
• short loop pf Henle
• reabsorption and secretion

Question 14

What is glomerular filtration? (8)

Answer 14

a passive process in which hydrostatic pressures force the fluids and solute through a membrane.
- ~20% of plasma filters into Bowman’s Capsule
- Forms a filtrate that is free of cells & proteins

Question 15

What is special about golmerular capillaries? (8)

Answer 15

are specialized for filtration. These are the only capillaries in the body that are fed and drained by an arteriole (afferent and efferent).

Question 16

How do glomerular capillaries affect pressure? (8)

Answer 16

they maintain and increase blood pressure

Question 17

What affects the rate of filtration? (10)

Answer 17

• permeability of the capillaries
• surface area available for filtration
• constriction or dilation of the arterioles

Question 18

What is the most abundant cation in filtrate? (13)

Answer 18

sodium

Question 19

Na+ reabsorption is passive across luminal membrane and active _______________ across basolateral membrane. (13)

Answer 19

Na/K pump

Question 20

What does the active pumping of sodium generate? (13)

Answer 20

generates a gradient that couples to passive entrance of other substances (glucose, etc.) via co-transporters across the luminal membrane.

Question 21

Where does substances like H+, K+, and organic anions move? (14)

Answer 21

from the peritubular capillaries into the tubular lumen

Question 22

What does tubular secretion do? (14)

Answer 22

removes more of a substance than filtration alone
- Regulation of reabsorption and/or secretion is in response to hormones and paracrine/autocrine factors.

Question 23

Tubular secretion is an important mechanism for: (14)

Answer 23

• Disposing of drugs and drug metabolites
• Eliminating undesired substances or end products that have reabsorbed by passive processes (urea and uric acid).
• Removing excess K+
• Controlling blood pH

Question 24

What is urine? (15)

Answer 24

filtrate + secretum - reabsorption
- formed in the renal tubules

Question 25

Where does urine drain into? (15)

Answer 25

renal pelvis -> ureter -> bladder

Question 26

What is the reflex that makes you pee? (15)

Answer 26

micturition reflex - initiated by a nervous reflex (smooth muscle of the bladder walls to contract and the expel the urine)

Question 27

What is the external sphincter? (15)

Answer 27

- skeletal muscle - Contraction prevents urination even when smooth muscle contraction is strong

Question 28

What is incontinence? (18)

Answer 28

inability to control urination - More common in women

Question 29

What are common types of incontinence? (18)

Answer 29

stress incontinence (due to sneezing, coughing, or exercise) - Treatment: Medications (such as estrogen replacement), therapy (to improve vaginal tone), Surgery (improve vaginal support of the bladder and urethra) urge incontinence (associated with the desire to urinate). - Any irritation to the bladder or urethra (e.g., with a bacterial infection) - Treatment: Medication (that antagonize the effects of the parasympathetic nerves on the detrusor muscle)

Question 30

How does antagonizing the parasympathetic nervous system help incontinence? (18)

Question 31

Na+ reabsorption occurs in all tubular segments except what? (19)

Answer 31

the descending limb of the loop of henle

Question 32

By what process is water reabsorbed? (19)

Answer 32

osmosis (passive)

Question 33

What does water move through? (19)

Answer 33

aquaporin channels - presence of these aquaporins varies throughout the tubule segments. - highly expressed in the proximal tubule. - Varies in different segments of loop of Henly - absent in the collecting ducts unless Anti-diuretic hormone (ADH) is active.

Question 34

go over slide 21 & 22

Answer 34

kk

Question 35

Why is it important that our bodies can make a concentrated urine? (23)

Answer 35

- to reduce water loss

Question 36

The descending limb of the loop of Henle is ___ (23)

Answer 36

- impermeable to solutes - permeable to water

Question 37

The ascending limb of the loop of Henle is ___ (23)

Answer 37

- impermeable to water - permeable to solutes

Question 38

Medullary interstitial fluid is _____ (23)

Answer 38

hyperosmotic - Partially due to urea recycling

Question 39

Go over slide 24

Answer 39

*thumbs up*

Question 40

Why is the osmolarity of the interstitial fluid always slightly higher? (24)

Answer 40

the active pumping of salt, increases the osmolarity of the interstitial fluid which allows for the passive reabsorption of water

Question 41

What is urea? (25)

Answer 41

- Helps maintain hyperosmotic medullary interstitial fluid - Urea is freely filtered in glomerulus - 50% is reabsorbed in proximal tubule - Various stages of secretions and reabsorption. - ~15% of that originally filtered is excreted in urine

Question 42

What are juxtaglomerular cells? (26)

Answer 42

enlarged smooth muscle cells that secrete the hormone renin

Question 43

What do JG cells do? (26)

Answer 43

mechanoreceptors (sense blood pressure) in the afferent arteriole

Question 44

What are macula densa cells? (26)

Answer 44

group of tall, closely-packed cells that line a portion of the distal tubule. -These cells work in tandem and are critical regulators of blood pressure.

Question 45

How can glomerular filtration rate be reduced? (27)

Answer 45

can be reduced in response to increase Na+ and water loss. (ex. Diarrhea)

Question 46

What are the mechanisms of glomerular filtration rate? (27)

Answer 46

- Activation of sympathetic nerves - Reduction of arterial blood pressure

Question 47

If your body is trying to increase fluid, does your body increase or decrease glomerular filtration? (27)

Answer 47

decrease filtration

Question 48

What are three inputs to juxtaglomerulary cells? (28)

Answer 48

- Sympathetic nerves - Arterial pressure - Sodium sensors in macula densa

Question 49

Go over slide 29 & 30

Answer 49

o k