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Biology > TEST - Nutrition, Digestion, Absorption & Homeostasis > Flashcards

TEST - Nutrition, Digestion, Absorption & Homeostasis Flashcards

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1
Q

Distinguish between essential and non-essential nutrients.

A

Essential - CANNOT be synthesized by the body(must be consumed through the diet).
Non-Essential - CAN be synthesized by the body.

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2
Q

Outline the causes and treatments of PKU.

A

Cause - genetic, lack of enzyme that breaks phenylalanine into tyrosine, causes buildup of phenylalanine
Treatment for PKU - low protein diet, limit intake of protein sources that contain phenylalanine; supplemented with formula containing essential aa’s/ tyrosine

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3
Q

Outline WHY food needs to be digested.

A

Food macromolecules need to be hydrolyzed into smaller molecules in order to be absorbed.

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4
Q

Pepsin / endopeptidase

A
  • Hydrolyzes protein into amino acids
  • Pepsin secreted by the gastric glands in the stomach (acidic pH)
  • Endopeptidase secreted by pancreas into the lumen of the small intestine (neutral pH)
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5
Q

Amylase

A
  • Hydrolyzes carbs (starch) into maltose
  • Salivary produced in salivary glands and acts in mouth (neutral pH)
  • Pancreatic produced in pancreas and acts in lumen of small intestine (neutral pH)
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6
Q

Lipase

A
  • Hydrolyzes lipids into di- / mono-glycerides / fatty acids / glycerol
  • Produced by pancreas and acts in the lumen of the small intestine (neutral pH)
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7
Q

Nuclease

A
  • Hydrolyzes nucleotides (nucleic acids) into nucleosides
  • Produced by pancreas and acts in the lumen of the small intestine (neutral pH)
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8
Q

If IB simply states “digestion” in a question without stating which type they mean, what do they mean?

A

“Chemical Digestion”

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9
Q

Outline the roles of hydrochloric acid in the stomach.

A
  • Lowers the pH, which initially denatures proteins
  • Activates pepsinogen into pepsin
  • Kill pathogenic bacteria and fungi in ingested foods
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10
Q

Outline the roles of proton pumps in the stomach.

A
  • Maintain acidic conditions (low pH) by actively pumping protons into the stomach
  • Cl combines to form HCL
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11
Q

Outline the roles of PPI’s in the reduction of stomach acid/ ulcers.

A
  • Proton pumps maintain acidity
  • PPI’s bind irreversibly to proton pumps
  • Lowers the amount of acid produced
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12
Q

Outline the hormonal and nervous mechanisms that control the secretion, content, and volume of gastric juice.

A
  • Sight/smell of food triggers medulla to send signal to stomach to secrete gastric juice via vagus nerve
  • Impulses from stretch receptors send signals to medulla via vagus nerve which sends signals to stomach to trigger production of gastrin
  • Gastrin causes sustained release of gastric juices (HCL)
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13
Q

Which cells in the gastric pits secrete which components of gastric juice?

A
  • HCl secreted by parietal cells
  • Pepsinogen secreted by chief cells
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14
Q

Where does chemical digestion and most absorption happen?

A

Small intestine

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15
Q

Where does protein digestion begin?

A

Stomach

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16
Q

What enzymes does the pancreas secrete?

A

Amylase, Lipase, Endopeptidase(Protease), Nuclease

17
Q

Function of the villi.

A

Maximum absorption of nutrients by increasing surface area.

18
Q

Explain how the structure of a villus is adapted to its function.

A

Epithelial cells - surround each villus (decreases diffusion distance of nutrients into bloodstream)
Rich Capillary Network - large concentration gradient (between blood and fluid in small intestine) allows for rapid absorption of nutrients
Lacteals - Absorb lipids (into lymphatic system – transports fats, drains tissues of excess fluids)
Intestinal crypts - release juices that act as ‘carrier fluids’ for nutrients

19
Q

List and explain the different forms of transport used by the small intestine to absorb different nutrients.

A

Diffusion - fatty acids absorbed through conc. gradient
Facilitated Diffusion - fructose pumped through protein channels in the epithelial cell membrane
Active transport (uses ATP) - glucose/amino acids pumped through protein channels against conc. gradient
Endocytosis - cholesterol in lipoprotein particles transported by means of vesicles.

20
Q

Outline the role of the large intestine.

A
  • Absorbs water / minerals / vitamins / ions
  • Peristalsis (contraction of muscles) to move food undigested food
  • Secretes mucous (lubrication)
21
Q

Explain why cellulose and lignin are not digested in humans.

A

Humans do not possess the enzymes needed to break them down.

22
Q

Outline the roles of fiber in the diet.

A
  • More fiber = faster rate of material movement through the intestine
  • Decreases hunger (prevents obesity)
  • Absorbs water to keep faces soft to pass (reduces constipation)
  • “Works out” microflora
23
Q

State the other substances that are egested (excreted) by the body.

A

BELCH
- Bile pigments
- Epithelial Cells
- Lignin
- Cellulose
- Human Microflora / bacteria

24
Q

Outline how the cholera toxin can cause dehydration.

A
  • Vibrio cholerae produces toxin
  • Toxin causes ions to be pumped into small intestine
  • Water follows gradient by osmosis, diluting faces (diarrhea) causing dehydration because water is being constantly removed from body
25
Q

Outline the cause, consequences, and treatments for stomach ulcers.

A

Cause - Helicobacter pylori infection, increases pH to neutralize stomach acid that kills it (urease), degrades mucous lining (mucinase)
Consequences - Inflammation, digestion of stomach lining by pepsin & HCL, pain
Treatments - Proton pump inhibitors reduce stomach acid production (bind irreversibly to proton pumps), lower acidity (high pH) helps ulcers to heal, antibiotics

26
Q

Outline the dual supply of blood to the liver and reasons why it is necessary.

A
  • Dual blood supply is blood entering liver form Haptic Artery and Hepatic Portal Vein.
  • Hepatic Portal Vein delivers nutrient-rich blood from the gut to liver
  • Hepatic Artery delivers oxygen-rich blood from the heart to liver
27
Q

Outline the circulation of blood through the sinusoids of the liver.

A
  • Blood enters thru the hepatic artery and hepatic portal vein and flows into sinusoids
  • Sinusoids surrounded by single layer of hepatocytes
  • Sinusoids remove excess nutrients to be stored in the liver, toxins, and add stored nutrients to the blood when needed (filter, detoxify, balance)
  • Prevents osmotic imbalance in blood
  • Clean & balanced blood exits liver thru HPV back into the heart
28
Q

Outline the structure and function of liver sinusoids.

A
  • Sinusoids remove excess nutrients to be stored in the liver, toxins, and add nutrients (stored in the liver) to the blood when needed.
  • Each sinusoid is lined with a single layer of hepatocytes, which detoxify, & store vitamins, minerals and molecules so they are available at ALL times. (carb and protein metabolism)
  • Contains Kupffer cells which engulf bacteria and break down old / damaged red blood cells (erythrocytes)
29
Q

Outline the role of the liver in the regulation of nutrient levels in the blood.

A
  • Liver stores glucose as glycogen (under influence of insulin/ glucagon (depending on blood glucose lvls): carbohydrate metabolism)
  • Kupffer cells in liver break down hemoglobin into heme and globin
  • Iron (from heme) is carried to bone marrow to produce new hemoglobin for new red blood cells
  • Some excess nutrients (Vitamins A/D, Iron) stored in liver
  • Liver detoxifies blood
  • Excess cholesterol covered into bile salts for bile which is secreted by liver (lipid metabolism)
30
Q

Explain how erythrocytes (red blood cells) are broken down and the recycling of their components by the liver.

A
  • Erythrocytes rupture after 120 days
  • Kupffer cells ingest erythrocytes in sinusoids of liver
  • Hemoglobin split into heme and globin groups
  • Heme broken down into iron group
  • Globin provides amino acids
  • Iron stored and transferred to bone marrow
  • Bilirubin becomes part of bile
31
Q

Outline the roles/ functions of hepatocytes in the sinusoids of the liver.

A
  • Excess glucose is stored as glycogen in hepatocytes
  • Hepatocytes break down globin into amino acids
  • Hepatocytes stores essential vitamins, minerals and molecules so they are available to the body at ALL times (to maintain homeostasis)
  • Hepatocytes synthesize and regulate cholesterol (for bile salt production)
32
Q

Outline the production of bile by the liver.

A
  • Bile is made of bile salts and bilirubin(bile pigment)
  • Hepatocytes convert heme into bilirubin
  • Bilirubin transferred to bile and normally excreted
33
Q

Outline the causes and consequences of jaundice.

A

Cause - blockage of bile ducts / disease in liver
Consequence - Bilirubin accumulates in blood, yellowing skin,

34
Q

Explain how the pancreas is able to act as an endocrine gland to regulate blood glucose levels.

A
  • Pancreas produces hormones that control levels of glucose
  • Beta cells produce insulin when blood-glucose is high
  • Alpha cells produce glucagon when blood-glucose is low
  • Insulin causes calls to take up glucose (increases muscle mass)
  • Glucagon causes liver to break down glycogen into glucose (increases glucose lvls in blood / decrease muscle mass)
  • ## Negative feedback control
35
Q

Explain the causes, symptoms, and treatments of type I diabetes.

A
  • Early onset
    Cause: Beta cells damaged/ destroyed by body’s own immune system: autoimmune disease (not enough insulin produced)
    Symptoms: High blood glucose levels, glucose in urine, increased thirst, fatigue.
    Treatments: Insulin injections which regulate blood-glucose levels
36
Q

Explain the causes, symptoms, and treatments of type II diabetes.

A

Adult onset
Cause: Insulin receptors on cells less sensitive to insulin, poor diet, obesity, genetics
Symptoms: High blood glucose levels, glucose in urine, thirst, fatigue
Treatments: High fiber foods satisfy appetite but aren’t broken down /
small meals to avoid rapid rise in glucose /
complex carbs w low glycemic index digested & absorbed slower

37
Q

Outline the role of leptin in the body.

A
  • Leptin secreted by adipose tissue
  • Acts on cells in the hypothalamus (appetite control center) to inhibit appetite
  • More adipose tissue = more leptin (means reduced appetite/eating)
  • Obese people can develop resistance to leptin

Biology (16 decks)

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