Integrated sci

What organelle produces digestive enzymes?

Rough endoplasmic reticulum and ribosomes.

What are the fluid components in the body?

Intracellular fluid and extracellular fluid; ECF includes plasma, interstitial fluid, and lymph.

Define total body water (TBW).

All water in the body; about 60% of body weight in an average adult.

What is the difference between cations and anions?

Cations are positive ions; anions are negative ions.

What is pH and how is it calculated?

pH measures hydrogen-ion concentration: pH = -log[H+].

What does each 1-unit pH change represent?

A 10-fold change in [H+].

What is the difference between acidic, neutral, and alkaline solutions?

Acidic: pH below 7; neutral: pH 7; alkaline: pH above 7.

What is the difference between strong and weak acids?

Strong acids ionize almost completely; weak acids ionize only partly.

What does Ka measure?

Acid dissociation: Ka = [H+][A-]/[HA].

What is the relationship between Ka and pKa?

pKa = -log Ka; larger Ka/lower pKa means a stronger acid.

What is the Henderson-Hasselbalch equation?

pH = pKa + log([A-]/[HA]); it relates pH to acid and conjugate-base amounts.

What is the difference between hypertonic, isotonic, and hypotonic solutions?

Hypertonic shrinks cells; isotonic causes no net size change; hypotonic swells cells.

Define metabolism.

The total of all chemical reactions in cells.

What are the two phases of metabolism?

Anabolism builds molecules and uses energy; catabolism breaks molecules down and releases energy.

Give an example of an anabolic process.

Amino acids -> protein.

What is anabolism?

The process of building up larger molecules from smaller ones, such as amino acids into proteins.

What is catabolism?

The process of breaking down larger molecules into smaller ones, such as glucose into CO2, water, and energy.

Define nutrient.

A food substance needed for energy, growth, or body regulation.

What is the difference between macronutrients and micronutrients?

Macronutrients are needed in large amounts; micronutrients are needed in small amounts.

What is the function of digestion?

To break food into small molecules that can be absorbed.

What is the difference between metabolism and digestion?

Digestion breaks down food in the GI tract; metabolism includes chemical reactions inside cells.

What are the phases of complete digestion of macromolecules?

Ingest -> mechanically and chemically digest -> absorb nutrients -> eliminate waste.

What are the components of the digestive system?

Mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus, and accessory organs.

What is the difference between mechanical and chemical digestion?

Mechanical digestion physically breaks food; chemical digestion uses enzymes to split molecules.

What types of cells secrete substances in the stomach?

Goblet/mucous cells, parietal cells, chief cells, G cells, and ECL cells.

What do stomach cells secrete?

Mucous: mucus; parietal: HCl and intrinsic factor; chief: pepsinogen; G: gastrin; ECL: histamine.

Where does carbohydrate digestion begin?

In the mouth.

Where does protein digestion begin?

In the stomach.

Which organ completes digestion?

The small intestine.

What are brush-border enzymes and where are they found?

Digestive enzymes on the microvilli of small-intestinal cells.

Define bolus, mastication, and deglutition.

Bolus: swallowed mass of food; mastication: chewing; deglutition: swallowing.

What are the functions of gastrin, secretin, and CCK?

Gastrin increases stomach acid; secretin increases bicarbonate-rich pancreatic juice; CCK releases pancreatic enzymes and contracts the gallbladder.

What is chyme and where is it first produced?

A creamy mixture of food and gastric juice first produced in the stomach.

What are the ionizable groups in amino acids?

The alpha-carboxyl, alpha-amino, and certain side-chain groups.

What is the difference between D- and L-amino acids?

They are mirror-image forms; human proteins mainly contain L-amino acids.

What is the difference between standard and nonstandard amino acids?

Standard amino acids are directly encoded for proteins; nonstandard ones are modified or not directly encoded.

How is pI calculated for a neutral amino acid?

pI = (pKa of COOH + pKa of NH3+)/2.

What is the difference between essential and nonessential amino acids?

Essential amino acids must come from food; nonessential amino acids can be made by the body.

What is the difference between glucogenic and ketogenic amino acids?

Glucogenic amino acids form glucose precursors; ketogenic amino acids form ketone-body or fat precursors.

How are amino acids converted to specialized products?

Enzymes modify amino acids; examples include histidine -> histamine and tryptophan -> serotonin.

What is protein turnover?

The continuous breakdown and replacement of body proteins.

What is the amino acid pool?

All free amino acids available in blood and cells for protein synthesis and other uses.

What are the unionized and ionized forms of amino acids?

Unionized: NH2-CH(R)-COOH. Zwitterion: +NH3-CH(R)-COO-.

Define zwitterion.

A molecule carrying both positive and negative charges but no net charge.

How are amino acids classified?

Grouped by side-chain polarity, charge, structure, nutritional need, or metabolic fate.