renal objectives 1-5 (kidney function and hormone stuff) Flashcards

1
Q

What is the glomerulus?

A

A group of capillaries that loop into a circle, serving as a filtration membrane.

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2
Q

How does blood enter and exit the glomerulus?

A

Blood enters via the afferent arteriole and exits via the efferent arteriole.

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3
Q

What is the function of the glomerular capillary walls?

A

They serve as a filtration membrane, pulling water and small solutes out of the blood.

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4
Q

What happens to water and small solutes filtered by the glomerulus?

A

They enter Bowman’s capsule.

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5
Q

Name some of the small solutes that pass through Bowman’s capsule.

A

Glucose, sodium, chloride, amino acids, and urea (similar to blood plasma).

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6
Q

What large solutes do not pass through Bowman’s capsule?

A

Red blood cells (RBCs), platelets, and proteins.

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7
Q

After leaving Bowman’s capsule, where does the fluid go?

A

It moves to the proximal convoluted tubule (PCT).

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8
Q

What does the proximal convoluted tubule reabsorb?

A

Sodium, water, glucose, amino acids, phosphate, and 80% of filtered bicarbonate (HCO3-).

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9
Q

What is secreted from the bloodstream into the tubules for excretion?

A

Potassium (K+), hydrogen ions (H+ or acid), and medications.

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10
Q

How do the kidneys regulate blood pH?

A

By adjusting the reabsorption of bicarbonate (HCO3-) and the excretion of hydrogen ions (H+).

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11
Q

Which part of the nephron is important for acid-base balance?

A

Both the proximal convoluted tubule (PCT) and the distal convoluted tubule (DCT) are involved.

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12
Q

What is the proximal convoluted tubule (PCT) responsible for?

A

It reabsorbs sodium, water, glucose, amino acids, phosphate, and 80% of filtered bicarbonate (HCO3-), helping to maintain acid-base balance.

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13
Q

After the Loop of Henle, where does the fluid go?

A

It moves to the distal convoluted tubule (DCT).

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14
Q

What substances are reabsorbed in the distal convoluted tubule (DCT)?

A

Some sodium (Na+) and calcium (Ca2+).

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15
Q

How is calcium reabsorbed in the DCT?

A

By the effects of parathyroid hormone (PTH), which enhances the synthesis of calcium transport proteins.

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16
Q

How does the DCT adjust pH depending on blood acidity?

A

The DCT may either: - Excrete H+ (acid) and reabsorb bicarbonate to raise blood pH. - Excrete bicarbonate and reabsorb H+ to lower blood pH.

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17
Q

How much of the cardiac output do the kidneys receive?

A

20-25% of the cardiac output.

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18
Q

What is the glomerular filtration rate (GFR)?

A

The amount of plasma filtered by the glomerulus per minute. Normal GFR is 125 mL/min.

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19
Q

What percentage of plasma is filtered by the glomerulus each minute?

A

20% of the plasma that flows through is filtered per minute.

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20
Q

What is the relationship between GFR and capillary perfusion pressure?

A

GFR is directly related to the perfusion pressure in the glomerular capillaries.

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21
Q

What happens to GFR if mean arterial pressure decreases or vascular resistance increases?

A

There is a drop in glomerular filtration.

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22
Q

What role does renal blood flow play in GFR?

A

Renal blood flow supplies the capillaries with plasma for filtration, which is essential for maintaining GFR.

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23
Q

What are the three mechanisms that regulate renal blood flow?

A
  1. Autoregulation 2. Neural regulation 3. Hormonal regulation (Renin-Angiotensin-Aldosterone System - RAAS)
24
Q

What is the goal of autoregulation in the kidneys?

A

To maintain a consistent GFR by preventing large fluctuations in BP from affecting the glomerular capillaries.

25
What happens to afferent arterioles when systemic BP increases?
Afferent arterioles constrict to prevent an increase in GFR and filtration pressure.
26
What happens to afferent arterioles when systemic BP decreases?
Afferent arterioles dilate, allowing GFR and filtration pressure to increase.
27
What system innervates the blood vessels of the kidneys in neural regulation?
The sympathetic nervous system.
28
What happens when systemic arterial pressure drops (e.g., in shock)?
Baroreceptors send messages to the brain, triggering increased sympathetic activity, which constricts the arterioles, decreasing renal blood flow and GFR.
29
Why does GFR decrease during neural regulation?
To retain salt and water in the bloodstream, helping to maintain systolic blood pressure.
30
What is an example of neural regulation during exercise or dehydration?
Mild arteriole constriction decreases GFR to retain salt and water, preventing dehydration.
31
How does the body respond to hypoxia?
Chemoreceptors in the carotid and aorta trigger sympathetic stimulation in the kidneys, decreasing renal blood flow and GFR to conserve water and improve perfusion.
32
What does the renin-angiotensin-aldosterone system (RAAS) regulate?
Blood volume, electrolyte balance, and systemic vascular resistance.
33
How does angiotensin II affect blood vessels?
It constricts blood vessels, increasing systemic vascular resistance.
34
What is the role of aldosterone in the kidneys?
Aldosterone triggers the retention of salt and water, increasing systemic vascular resistance and capillary hydrostatic pressure.
35
Which hormones act on the kidneys?
1. Antidiuretic hormone (ADH) 2. Aldosterone 3. Natriuretic peptides
36
Which hormones are activated or synthesized in the kidneys?
1. Vitamin D (activated) 2. Erythropoietin (synthesized)
37
What hormone increases water reabsorption in the distal tubule and collecting ducts?
Antidiuretic hormone (ADH), secreted by the posterior pituitary gland.
38
What is the function of ADH?
Increases blood pressure by promoting water reabsorption in the distal tubule and collecting ducts.
39
Where does aldosterone act on the kidneys?
Distal tubule and collecting ducts.
40
What is the main function of aldosterone?
Increases blood pressure by promoting sodium and water reabsorption, prevents hyperkalemia, and regulates pH by excreting potassium (K+) and hydrogen (H+).
41
Which hormone prevents hyperkalemia and promotes pH regulation in the kidneys?
Aldosterone, secreted by the adrenal gland.
42
What is the role of natriuretic peptides?
Inhibit sodium and water reabsorption, inhibit renin and aldosterone secretion, and promote vasodilation of afferent arterioles.
43
Where are natriuretic peptides secreted from?
Atria and ventricles of the heart in response to wall dilation.
44
How do natriuretic peptides affect urination?
They promote increased urination by dilating efferent arterioles,
45
How is vitamin D activated in the kidneys?
After being initially processed in the liver, it is activated in the kidneys by the action of parathyroid hormone (PTH).
46
What is the role of vitamin D in the body?
Promotes absorption of calcium and phosphorus in the small intestine.
47
What hormone stimulates the bone marrow to produce red blood cells (RBCs)?
Erythropoietin, which is synthesized in the kidneys.
48
What triggers the release of erythropoietin?
Decreased oxygen delivery to the kidneys, leading to secretion by peritubular cells to stimulate RBC production.
49
What is the main function of erythropoietin?
To prevent or correct hypoxia by stimulating the bone marrow to produce more red blood cells for oxygen transport.
50
Where does fluid go after the distal convoluted tubule?
It goes to the collecting duct.
51
What do several nephrons merge into after the collecting ducts?
They form cortical collecting ducts.
52
Which hormones influence the cortical collecting ducts?
Antidiuretic hormone (ADH) and aldosterone.
53
What is the effect of ADH and aldosterone on the cortical collecting ducts?
They stimulate water and salt reabsorption and promote potassium excretion.
54
What substances can be excreted or reabsorbed in the collecting ducts?
Sodium (Na+), potassium (K+), hydrogen (H+), and bicarbonate (HCO3-).
55
What happens to sodium, potassium, hydrogen, and bicarbonate in the collecting ducts?
They may either be excreted from the bloodstream into the duct or reabsorbed into the bloodstream.