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MCAT Biochem > Renal and Digestive System > Flashcards

Renal and Digestive System Flashcards

(61 cards)

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1
Q

Colon Function

A

Eliminates solid waste, material that was eaten but not absorbed

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2
Q

Liver function

A

Eliminates hydrophobic waste
Material that was eaten and absorbed in the blood, but too hydrophobic to dissolve in the plasma
- Alcohol, acetaminophen

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3
Q

Kidney Functions

A

Eliminates hydrophilic waste
Material that was eaten, absorbed in the blood, and dissolved in the plasma

  1. Regulates blood pressure
  2. Regulates ion balance
  3. Regulates water balance
  4. Regulates pH
  5. Secretes EPO (Erythropoietin), EPO stimulates red blood cell formation
  6. Activates vitamin D
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4
Q

What are the kidneys sensitive to and what is their response?

A

The functions of the kidney require active transport. Active transport required ATP, which requires oxygen.
Thus, the kidneys are sensitive to drops in oxygen. If oxygen levels drop, the kidneys secrete EPO to stimulate RBC formation to supply oxygen to the system.

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5
Q

Internal Urinary sphincter

A

Made of smooth muscle
Under involuntary control
If relaxed, urine will flow to the external urinary sphincter
- This is where we feel the urge to urinate

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6
Q

External urinary sphincter

A

Skeletal muscle

Under voluntary control

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7
Q

Bladder function

A

Urine storage

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8
Q

Ureter function

A

Tube that drains from the kidney to the bladder

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9
Q

Flow from the kidney

A

Kidney -> ureter -> bladder -> internal sphincter -> external sphincter -> out through the urethra

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10
Q

Nephron

A

Functional unit of the kidney

All modifications to urine happen at the nephron

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11
Q

3 processes the of the nephron to produce urine

A
  1. Filtration - moves a substance across a membrane using pressure
    (Moves blood plasma across capillary walls utilizing blood pressure)
  2. Reabsorption - move a substance from the filtrate into the blood.
  3. Secretion - moves a substance from the blood to the filtrate
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12
Q

What is always secreted?

A

Drugs, toxins, and creatinine

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13
Q

What is always reabsorbed?

A

Glucose, amino acids, and water

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14
Q

Ions

A

Can be secreted or absorbed
Typically reabsorb sodium and bicarbonate
Typically secrete potassium and H+

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15
Q

Creatinine Function

A

Creatinine is a metabolic product of muscle function, which is constantly occurring in the body
Is a measure of kidney function.

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16
Q

Glomulerus Function

A

Filtration

Can’t filter proteins

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17
Q

Afferent vs Efferent arteriole

A

Afferent approaches the glomerulus
Efferent exits the glomerulus (Is very high in protein because they can’t be filtered)
We can dilate the afferent while constricting the efferent, increasing blood flow in and increasing volume and pressure in the capillary bed.

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18
Q

Proximal tubule function

A

Most reabsorption and secretion occurs here
Most water, glucose, and amino acids are reabsorbed here
Roughly isotonic to plasma at this point

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19
Q

Loop of Henle function

A

Sets up the concentration gradient in the medulla

Osmolarity increases the deeper in the medulla you go (Increased salt concentration)

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20
Q

Descending Loop of Henle

A

Permeable to water, but impermeable to salt (Loses water)

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21
Q

Ascending Loop of Henle

A

Permeable to salt, but impermeable to water
Sodium is actively transported at the top of the loop into the surrounding tissue, drawing water out of the descending loop
Sodium is passively transported out at the bottom of the loop

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22
Q

Distal Tubule Function

A

Specialized reabsorption and secretion

Sodium reabsorption here is regulated by aldosterone

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23
Q

Calcium reabsorption is regulated by what two hormones

A

Calcitonin and Parathyroid hormone

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24
Q

Collecting Duct Function

A

Regulates water reabsorption

Do we want to retain or pee it out

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25
ADH Function
Anti-diuretic hormone If ADH is present, the walls of the collecting duct are permeable to water and water will be reabsorbed If ADH isn't present, the walls of the collecting duct aren't permeable and water will be subsequently urinated
26
Dehydration/Hydration and ADH
If dehydrated, increase ADH to promote water reabsorption Alcohol and caffeine are diuretics - they inhibit ADH, forcing you to urinate even if you're dehydrated
27
Renin-Angiotensin system
How BP is regulated by the kidney If blood pressure falls, the kidney secretes renin Renin is an enzyme that converts inactive angiotensinogen into angiotensin 1 (active) Angiotensin 1 is converted to angiotensin 2 by ACE (angiotensin converting enzyme) Angiotensin 2 causes systemic vasoconstriction and increased aldosterone release
28
Angiotensin 2 Functions
When active, it causes systemic vasoconstriction (which increases blood pressure) and releases aldosterone Aldosterone increases sodium reabsorption by the distal tubule More sodium = increased osmolarity, triggering the release of ADH ADH causes increased water reabsorption, which increases blood volume, and increases blood pressure
29
Juxtaglomerular Apparatus
The contact point between the afferent arteriole and the distal tubule
30
The afferent arteriole is what kind of receptor, and what does it do
Baroreceptors, which monitor blood pressure | If blood pressure falls, the baroreceptors release renin
31
The distule tubule contains what kind of receptors and what is their function
Chemoreceptors, detecting changes in osmolarity Decreased osmolarity: 1. Stimulates afferent arteriole to release renin 2. Directly dilates the afferent arteriole (Increasing volume and BP in the capillaries)
32
What happens when blood pressure is high?
The atria detect the heart stretch The right atrium releases ANP (Atrial Natriuretic Peptide) ANP is a vasodilator and inhibits the release of renin and aldosterone
33
How is pH regulated by the kidney?
Renal regulation of blood pH is slow | Carbonic anhydrase is an enzyme that increases the rate of carbonic acid formation, which dissociates into bicarbonate
34
Bicarbonate buffer system
CO2 + H2O H2CO3 H+ + HCO3-
35
What happens when blood pH is too acidic/basic?
Acidic: Increase bicarbonate reabsorption and increase H+ secretion Basic - Decrease bicarbonate reabsorption and decrease H+ secretion
36
What is the Alimentary Canal?
Muscular tube, mouth to anus
37
What are the accessory organs?
Organs with a digestive role, but are not part of the Alimentary Canal Liver, Gallbladder, Pancreas, and the Salivary glands
38
Liver digestive function
Produces bile, which breaks down fats for easier digestion
39
Bile function
Bile is an amphipathic molecule that breaks down fats for easier digestion
40
Gallblader Function
Stores and concentrates the bile produced by the liver | No gallbladder = can't eat a lot of fat because it won't be broken down as effectively
41
Pancreas Functions
Secretes insulin and glucagon Major source of digestive enzymes (Proteases, lipases, amylases, and nucleases) Releases bicarbonate to optimize the function of its enzymes
42
Amylase function
Breaks down starch
43
Nuclease function
Breaks down nucleic acids
44
Alimentary Canal wall components
Mucosa - epithelial tissue attached to the lumen Submucosa - connective tissue that contains the blood vessels and nerves that supply the digestive tract Circular muscle - runs around the circumference of the tube (composes sphincters) Longitudinal muscle - runs along the length of the tube Serosa - connective tissue that forms the perineal membrane
45
Peristalsis
Involuntary contraction and relaxation of circular and longitudinal muscles that work together to move food down the digestive tract
46
Mouth (Function, structure, exocrine and endocrine functions)
Functions - grind food, moisten food, and begin starch digestion Structure - teeth, tongue, and salivary glands Exocrine - secretes saliva (mostly water, mucus, and enzymes), lysozymes that kill bacteria, and amylase No endocrine function
47
Esophagus (Function, structure, exocrine and endocrine functions)
Function - tube that brings food down to the stomach Structure - starts as skeletal muscle and transitions to smooth muscle Cardiac sphincter is at the bottom of the esophagus to prevent stomach contents from refluxing back up No exocrine or endocrine function
48
Stomach (Function, structure, exocrine and endocrine functions)
Very limited digestion and absorption - main job is to serve as a storage tank for food Composed of gastric glands and the pyloric sphincter Exocrine - mucous cells, parietal cells, and chief cells Endocrine - secretes Gastrin, which is produced by G cells
49
Gastric glands
In the stomach Mucous cells - secrete mucous Parietal cells - secrete HCl Chief cells - secrete pepsinogen (innate immunity)
50
Pepsinogen
Produced by the chief cells within the stomach. Initially inactive, as it moves up the pit the parietal cells dump HCl on them which activate them. Are proteases that provide innate immunity by reducing infection
51
Pyloric sphincter
Sphincter of the stomach that regulates entry into the small intestine
52
Gastrin
Produced by G-cells in the stomach Gastrin increases the productivity of the gastric glands Operate under negative feedback by pH Eat a meal, increasing gastrin secretion, stimulating the gastric glands, lowering the pH, inhibiting further gastrin release
53
Small Intestine (Function, structure, exocrine and endocrine functions)
Where most digestion/absorption is performed Duodenum (5%) Jejunum (40%) Ileum (55%) See a huge increase in surface area to increase digestion via mucosa, plicae, villus, microvilli (brush border) Produces enterokinase (Enteropeptidase) and brush border enzymes (Disaccharides, dipeptidases) Endocrine - Produces enterogastrone, CCK, and Secretin
54
Enterokinase Function
An enzyme of the small intestine | Activates trypsinogen, a pancreatic protease that sets off a chain of enzyme activation
55
Brush Border enzymes
Enzymes of the small intestine The last step in digestion Disaccharidases and dipeptidases that break molecules into monomers
56
Trypsinogen
Activated by enterokinase | A pancreatic protease that cleaves enzymes, setting off a chain of enzyme activation
57
Enterogastrone
Produced by the small intestine | Released when food is in the intestine, reduces stomach motility
58
Secretin
Produced by the small intestin | Stimulates the pancreas to release bicarbonate and is triggered by low pH
59
CCK (Cholecystokinin)
Produced by the small intestine Increases bile release from the liver and gallbladder Triggered by fats and proteins
60
Large Intestine (function, structures, endocrine and exocrine function)
Function - reabsorbs water and stores feces (No digestion) Contain colonic bacteria that secrete vitamin K and reduce the growth of pathogens Ileocecal valve and internal/external anal sphincters No exocrine or endocrine function
61
Ileocecal valve
Found between the small and large intestine | Is usually closed, relaxes when we eat a big meal to clear room in the small intestine. Initiates defecation reflex

MCAT Biochem (2 decks)

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