Urinary System Flashcards Preview

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Flashcards in Urinary System Deck (35)
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1
Q

What is the function of the urinary system?

A
  • Removes metabolic wastes
  • Kidneys filter blood, removing toxins, metabolic wastes, excess ions
  • Returns nutrients back to blood
2
Q

Describe the stages of filtration

A

1) Excretion
- removal of metabolic wastes
2) Elimination
- Discharge of wastes from body
3) Homeostatic regulation
- controls volume and solute concentration

3
Q

What are homeostatic function of the urinary system?

A

1) Regulating blood volume and blood pressure
2) Regulating plasma ion concentration
3) Helps to stabilise blood PH
4) Conserves valuable nutrients
5) Assists liver

4
Q

Describe the structure and location of the kidneys

A
  • Bean shaped, lies at back of abdominal lining
  • Has renal fascia (dense connective tissue surrounding kidneys), fatty mass protecting kidney from trauma & fibrous capsule protecting from infection
5
Q

What is the function of the adrenal gland?

A

Triangle shaped endocrine glands that produce adrenaline/noradrenaline (stress response), cortisol (influences metabolism) and aldosterone (controls BP)

6
Q

What is the renal cortex?

A

Outer granular region that contains the nephron

7
Q

What is the renal medulla?

A
  • Middle region with renal pyramids
  • Empty urine from minor –> major calyx
  • Transports urine to renal pelvis
8
Q

What is the renal pelvis?

A

-Inner region
-Drains into ureters
Each kidney receives blood through renal artery to arterioles

9
Q

What is the nephron

A

Structural and functional unit of the kidneys

10
Q

Describe the renal corpuscles

A
  • Consists of 2 parts:
    1) Bowman’s Capsule
  • surrounds glomerulus capillaries
    2) Glomerulus
  • Afferent arterioles brings blood into nest of capillaries
  • Filtered blood returned to circulation via efferent arteriole: blood cells, large proteins
  • Renal corpuscle produce filtrate: enters renal tubule
11
Q

Describe the renal tubule

A
  • Tubular fluid gradually changes in composition: substances reabsorbed or secreted
    1) Proximal convoluted tubule
    2) Loop of henle
    3) Distal convoluted tubule
  • Reabsorb useful organic nutrients that enter filtrate
  • Reabsorb water
  • Secrete waste products
12
Q

Describe glomerular filtration

A

Blood hydrostatic pressure forces fluid and solutes through filtration membrane

13
Q

What is the glomerular filtration rate (GFR) ?

A
  • Amount of filtrate kidneys produces

- Dependent on net filtration pressure, total filtration surface area and filtration membrane permeability

14
Q

Describe intrinsic regulation of GFR

A
  • Locally acting at kidney
  • Renal regulation of GFR
  • Changing diameter of afferent arteriole, efferent arterioles and glomerular capillaries
  • Reduced blood flow triggers:
  • Dilation of afferent arteriole
  • Constriction of efferent arteriole
15
Q

Describe neural extrinsic regulation of GFR

A

Sympathetic NS:

  • Adrenaline/Noradrenaline released, causes constriction of afferent arterioles
  • Decreased efferent renal sympathetic nerve activity
16
Q

Describe hormonal extrinsic regulation of GFR

A
  • RAAS system in response to low BP/low GFR to restore homeostasis
  • Constricts efferent arterioles, decreases blood flow out of glomerulus, increases GFR
17
Q

What is the process of the RAAS system

A
Homeostasis normal (normal GFR)
Homeostasis disturbed (decrease GFR)
Renin
Angiotensin activation
Elevation of BP and BV
Homeostasis restored (increased GFR)
18
Q

Describe at reabsorption at PCT

A

Substances for reabsorption diffuses out of tubular into blood capillaries

  • Reabsorption of nutrients
  • Active transport of ions
  • Reabsorption of water
  • Passive reabsorption of ions
  • Secretion
19
Q

Describe at reabsorption at nephron loop

A

Reabsorption of water and sodium/chloride ions, sets up concentration gradient

20
Q

Describe at reabsorption in DCT

A
  • Hormonally regulated

- Selective reabsorption alters solute composition and volume of tubular fluid

21
Q

Describe tubular secretion in PCT

A
  • Remove selected substances from blood back into tube

- Eliminates undesirable substances controls PH by altering H+ and HCO3- in urine

22
Q

What is aldosterone?

A
  • Promotes sodium reabsorption in collecting ducts

- Increase BV & BP, decrease potassium levels

23
Q

What is atrial natriuretic peptide?

A
  • Increases renal Na+ salt excretion in collecting ducts

- Reduces blood Na+, decrease blood volume and pressure

24
Q

What is parathyroid hormone?

A

Acts on PCT to increase calcium ion reabsorption

25
Q

What is antidiuretic hormone?

A
  • Cells of collecting ducts to reabsorb water

- Increased water absorption

26
Q

What happens when PH drops?

A

Becomes acidic

27
Q

What happens when PH rises?

A

Become basic

28
Q

What is filtrate?

A

Blood plasma minus blood proteins and blood cells

29
Q

What is urine?

A
  • Filtrate minus water, nutrients

- No glucose or amino acid, proteins

30
Q

What is the ureters?

A
  • Pair of muscular tubes

- Transport urine from kidneys to bladder by contraction

31
Q

What is the urethra?

A
  • Conveys urine from body

- External urethral sphincter

32
Q

What is the process for filtrate to urine?

A

1) Bladder stretches when >200mL
2) Activates stretch receptors in bladder wall
3) Parasympathetic impulses to spinal cord and back to bladder
4) Bladder contracts, internal sphincter relaxes and urine forced past sphincter into urethra
5) Urged to void
6) When not convenient: consciously contract external sphincter contractions stop
7) When >400mL urine collected, micturition occurs involuntary

33
Q

What are the component of the juxtaglomerular complex?

A

1) Macula densa
2) Juxtaglomerular cells
3) Extraglomerular mesangial cells

34
Q

Describe autoregulation of GFR

A
  • Intrinsic: local blood flow, low blood flow to glomerulus
  • Signals extraglomerular mesangial cell in afferent arteriole vasodilate
  • Increases blood flow into glomerulus: increase GFR
  • High blood flow to glomerulus: increase GFR, vasodilation of afferent arteriole
35
Q

Describe the RAAS system

A
  • Long term regulation of GFR
  • Decreases arterial blood pressure, releases renin
  • Angiotensin converting enzyme converts angiotensin I into angiotensin II
  • Angiotensin II causes vasoconstriction of efferent arteriole in nephron
  • Increase production of ADH
  • GFR returns to homeostasis