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PED 215 > Unit 5: Kidneys > Flashcards

Unit 5: Kidneys Flashcards

1
Q

What are the 6 main functions of the kidneys?

A

1) regulation of ECF volume and blood pressure
2) regulation of osmolarity
3) maintenance of ion balance
4) Homeostatic regulation of pH
5) excretion of wastes
6) production of hormones

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2
Q

Where are the kidneys located?

A
  • in the back of the abdominal cavity, between the peritoneum and the bones/muscles of the back
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3
Q

What is the outer portion of the kidney called? The inside portion?

A

outer portion = renal cortex

inner portion = renal medulla

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4
Q

What is the hollow tube leading from the kidney to the bladder?

A

ureter

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5
Q

What is the nephron

A
  • functional unit of the kidney
  • smaller unit that can perform all of the functions of the kidney
  • between 800,000 and 1.5 million nephrons per kidney
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6
Q

What are the two types of nephrons are how are they classified?

A
  • classified by their location and their length

- juxtamedullary nephrons and cortical nephrons (80% of nephrons)

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7
Q

What are the two components of the nephron? And what do each of them do?

A

Vascular Component:
- afferent arteriole: carries blood into the glomerulus
- glomerulus: a tuft of capillaries that filters aa protein-free plasma into the tubular component
- efferent arteriole: carries blood from the glomerulus
- peritubular capillaries: supply the renal tissue; involved in the exchanges with the fluid in the tubular lumen
Tubular Component:
- Bowman’s Capsule: collects the glomerular filtrate
- Proximal tubule: uncontrolled reabsorption and secretion of selected substances
- loop of Henle: establishes an osmotic gradient in the renal medulla that is important in the kidney’s ability to produce urine of varying concentration
- distal tubule and collecting duct: variable, controlled reabsorption of Na+ and H20 and secretion of K+ and H+ occur here; fluid leaving the collecting duct is urine, which enters the renal pelvis

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8
Q

What are the steps in renal blood flow?

A

renal artery–> afferent arterioles–> glomerular capillaries–> efferent arterioles–>proximal peritubular capillaries–> vasa recta–> distal peritubular capillaries–> collecting duct (capillaries and veins) –> renal venules

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9
Q

What are the 3 basic renal processes?

A

1) glomerular filtration: movement of the fluid from the blood into the lumen of the nephron
2) tubular reabsorption: substances from filtrate moved back into the blood (peritubular capillaries)
3) tubular secretion: removes molecules from blood and adds them in filtrate in the lumen

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10
Q

What are the three filtration barriers in the first step in urine formation?

A

1) glomerular wall capillary wall
2) basal lamina (basement membrane)
3) epithelium of Bowman’s Capsule

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11
Q

What are the 3 forces involved in glomerular filtration?

A

1) glomerular capillary blood (hydrostatic) pressure (55mmHg out of glomerulus)
2) plasma-colloid osmotic pressure (30mmHg back into glomerulus)
3) Bowman’s capsule hydrostatic pressure (15 mmHg back into glomerular
- -> net 10mmHg outward pressure

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12
Q

What is glomerular filtration rate (GFR)?

A
  • the volume of fluid that filters into Bowman’s capsule per unit time
  • influenced by: surface area of glomerular capillaries available for filtration and permeability of interface between the capillary and Bowman’s capsule
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13
Q

What kind of adjustments occur when GFR is too high? Too low?

A
  • if it is too high: excess water and solutes is lost due to high urine output
    if it is too low: waste builds up
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14
Q

List and describe the two control mechanisms of control adjustments made to the GFR?

A
  • auto regulation: prevents spontaneous changes to GFR
  • extrinsic sympathetic control: overrides auto regulatory responses, aimed at long-term regulation of arterial blood pressure
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15
Q

Where does most of tubular reabsorption occur?

A

Mostly in the proximal tubule but some occurs in the distal segments.

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16
Q

Where does tubular reabsorption occur?

A
  • from the tubular lumen into the peritubular capillaries
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17
Q

What are the 5 barriers in tubular reabsorption?

A

1) luminal membrane of tubular cell
2) pass through cytosol of tubular cell
3) basolateral membrane of the tubular cell
4) diffuse through interstitial fluid
5) pass through capillary wall to enter blood plasma

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18
Q

Where is the Na+-K+-ATPase pump located?

A

in the basolateral membrane of tubular cells

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19
Q

Where does tubular secretion occur?

A

-substances transfer from peritubular capillaries into the tubular lumen

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20
Q

What are the most important secretory system for and where are they secreted?

A

1) H+ (regulating acid-base balance)
- proximal, distal and collecting ducts
2) K+ (maintained membrane excitability in muscles and nerves)
- distal and collecting tubules controlled by aldosterone
3) Organic ions (waste removal)
- proximal tubule

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21
Q

What does excretion rate of a substance rely on?

A

1) filtration rate of the substance

2) whether the substance is reabsorbed and/or secreted

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22
Q

If less solute appears in the urine than the blood then _________________

A

reabsorption must have occurred

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23
Q

If more solute appears in the urine than the blood then __________________

A

secretion must have occurred.

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24
Q

What is the internal sphincter made of? The external sphincter?

A

internal sphincter: is the continuation of the bladder wall

external sphincter: ring of skeletal muscle controlled by somatic motor neurons

25
Q

What is the micturition reflex?

A

relaxation of the external urinary sphincter muscle allowing urine to pass through urethra and out of the body

26
Q

what is osmolarity?

A

a measure of the concentration of solute molecules in a solution

27
Q

What is diffusion?

A

passive movement of solutes from an area of high concentration to an area of low concentration

28
Q

What is osmosis?

A

movement of solvent molecules through a partially permeable membrane into a region of higher solute concentration

29
Q

What do diffusion and osmosis have in common?

A

they both equalize the concentration of two solutions

30
Q

What are the three systems that control fluid and electrolyte balance?

A

lungs (respriatory system), cardiovascular system, and the kidneys

31
Q

True or False: Water is approx. 50-60% of total body weight?

A

true

32
Q

Where is vasopressin released and what causes it to be released?

A

Released from the posterior pituitary when there are changes in blood osmolarity, blood volume and blood volume

33
Q

What are the 3 mechanisms of vasopressin release stimulation?

A

1) hypothalamic osmoreceptors
- increase osmolarity = increase thirst and increase VP secretion
- vice versa
2) left atrial volume receptors; carotid/aortic baroreceptors (senses BP)
- stimulate VP secretion and thirst when pressure decreases
- inhibit VP secretion and thirst when pressure increases
3) Angiotensin 2
- increase VP secretion and thirst when renin-angiotensin-aldonsteron system is activated to conserve Na+

34
Q

What happens to vasopressin release when there is an increase in osmolarity?

A
  • there is an increased release to increase water (conserve water)
35
Q

What happens to vasopressin release when there is a decrease in blood volume?

A

increased release to conserve water

36
Q

What happens to vasopressin release when there is a decrease in osmolarity?

A

decreased release (inhibited) because there is no need to conserve water

37
Q

What happens to vasopressin release when there is an increase in blood volume?

A

decreased release (inhibited) because there is no need to conserve water

38
Q

Explain the steps in the renin-angiotensin-aldosterone system (RAAS)

A

1) juxtaglomerular granular cells in afferent arteriole secrete renin when BP decreases or Na+ decreases
2) renin converts angiotensionogen (inactive) to angiotensin 1
3) Angiotension converting enzyme (ACE) converts angiotensin 1 to angiotensin 2
4) angiotensin 2 stimulates release of aldosterone from adrenal cortex
5) aldosterone promotes Na+ reabsorption in the kidney

39
Q

What does aldosterone promote the reabsorption in the kidneys of?

A

Na+

40
Q

Where is aldosterone secreted from and what is stimulated by?

A

-secreted from renal cortex and is stimulated by low BP, large drops in plasma Na+ and high plasma K+ concentration

41
Q

What are the 5 affects of angiotensin 2?

A

1) increases vasopressin secretion (conserve water, maintain BP)
2) Stimulates thirst (fluid ingestion with increase blood volume and blood pressure)
3) potent vasoconstriction (increase in BP without changes in blood volume)
4) activates receptors in the cardiovascular control centre to increase cardiac output and vasoconstriction
5) increases Na+ and water reabsorption in the kidney

42
Q

What does atrial natriuretic peptide (ANP) inhibit? Where is it secreted from and in what response is it secreted?

A
  • inhibits Na+ reabsorption in the distal tubule, renin and aldosterone secretion (increase Na+ and H20 excretion)
  • secreted by atria in response to being stretched
43
Q

What is hypokalema? Hyperkalemia?

A

Hypokalema: lower than normal K+ in blood, results in muscle weakness
Hyperkalema: higher than normal K+ in blood, can produce cardiac arrhythmias

44
Q

Name some causes to K+ imbalance.

A

kidney disease, eating disorders, diarrhea, use of certain diuretics, inappropriate rehydration, pH disturbance in the body

45
Q

What happens when there is a deficit of free water in the ECF? What is this called?

A

hypertonic solution: associated with dehydration, can lead to cell shrinking

46
Q

What happens when there is a excess free water in the ECF? What is this called?

A

hypotonic solution: associated with over hydration, kidneys can’t react fast enough, can lead to cell swelling

47
Q

What happens when ECF hypotonicity occurs?

A

swelling of brain cells, weakness, circulatory disturbances, water intoxication

48
Q

What happens when ECF hypertonicity occurs?

A

shrinking of brain neurons, circulatory disturbances, dry skin, sunken eyeballs, dry tongue

49
Q

How does the body respond to dehydration?

A

1) conserving fluid to prevent additional losses
2) Trigger CV reflexes in increase BP
3) stimulate thirst so that normal fluid volume can osmolarity can be restored

50
Q

What does pH express the concentration of?

A

H+ ions

51
Q

what pH range is classified as acidosis?

A

pH < 7.35

52
Q

What pH range is classified as alkalosis?

A

pH > 7.45

53
Q

What is the pH range that is compatible with life?

A

pH > 6.8 or < 8.0

54
Q

What are some sources of H+ in the body?

A
  • carbonic acid formation (H2CO3)
  • inorganic acids produced during breakdown of nutrients
  • organic acids resulting from intermediary metabolism
55
Q

T or F: there are a lot of sources of bases in the body

A

false: few and far between, excess acid is a much more common problem

56
Q

What are the 3 lines of defence against changes in [H+]? Explain each one.

A

1) Chemical buffer systems ( bind with free H+ or produce it when necessary+
- H2CO3, HCO3- buffer system: primary ECF buffer for non carbonic acids
- protein buffer system: primary ICF buffer, also buffers ECF
- hemoglobin buffer system: primary buffer against carbonic acid changes
- phosphate buffer system: important urinary buffer, also buffers ICF
2) Respiratory mechanism (CO2 removal)
- 2nd defence mechanism
- acts at a moderate speed
- regulates pH by controlling rate of CO2 removal (when H+ increases, rate of ventilation increases)
3) Kidneys (control retention/excretion)
- 3rd line in defence
- requires hours to days for full compensation
- control pH of body fluids by adjusting: H+ excretion, HCO3- excretion, ammonia secretion

57
Q

How does the body react to acidosis?

A
  • kidney secretes H+ into the tubule lumen using direct and indirect active transport
  • ammonia and phosphate ions in kidney act as buffers so that more H+ can be excreted
  • results in acidic urine
  • tubular cells can make new HCO3- form CO2 and H2O which is reabsorbed into the blood
58
Q

How does the body react to alkalosis?

A
  • kidney excretes HCO3- and conserves H+

- combination of active and passive transport through tubular epithelial cells

59
Q

What are the four different types of acid-base imbalances? Explain each

A

Respiratory acidosis: hypoventilation decreases CO2 loss through lungs, caused by lung conditions
Respiratory alkalosis: hyperventilations causes excessive loss of CO2, decrease H+, caused by fear, anxiety, physiological mechanisms at high altitude
Metabolic acidosis: any acidosis not respiratory in nature, caused by severe diarrhea, diabetes mellitus, strenuous exercise, kidney dysfunction
metabolic alkalosis: relative deficiency of non carbonic acids, caused by vomiting, indigestion of alkaline drugs

PED 215 (7 decks)

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