Chapter 41 Flashcards by Ibrahim Siddiqui

Two requirements of animals

Chemical energy from ATP
Carbon-containing molecules

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What are the 4 processes of obtaining energy from food

Ingestion
Digestion
Absorption
Elimination

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How many amino acids can be made from the human body

12 of the 20

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Minerals

Important cofactors or structural materials (Ca, Fe, MG, etc)

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What are vitamins

Organic compounds vital for health in minute amounts

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Electrolytes

Inorganic ions that influence osmotic balance; required for normal membrane function

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Digestive tract

Comes in two general designs

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adaptive radiation

Diversification of a single ancestral lineage into many species, each of which lives in a different habitat or emplys distinct feeding method

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Complete digestive tracts

Have two openings - mouth for ingestion and anus for elimination of wastes

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Complete digestive tract advantages

Can feed on larger pieces of food
Chemical & physical processes can be separated
within canal; can occur independently & in sequence
Material can be ingested & digested continuously;
flow of food is in one direction

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Where do chemical digestion of carbohydrates and lipids begin in?

mouth due to salivary amylase and lingual lipase attacking it

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Where do the chemical digestion of proteins occur?

stomach due to pepsin

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Where does digestion mostly occur in humans

Small intestine due to receiving digestive enzymes from pancreas and bile from liver

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What is the primary function of the small intestine

To better absorb nutrients

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Why do many acid reflux drugs contain proton pump inhibitors?

Blocking the pumps reduces the acidity of the stomach by reducing the number of protons pumped from the parietal cells into the lumen.

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What do bile salts do?

Act as emulsifying agents to break down large fat globules that are less digestible into small fat droplets easily digested by lipase. The drug would block this emulsification.

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What enzyme performs majority of chemical digestion of lipids

Pancreatic lipase

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What enzyme begins digestion of proteins in the stomach

Pepsin

What does pancreatic amylase do?

Digests disaccharides into monosaccharides in the small intestine.

What toothlike structures are found in East African Rift Lakes cichlid species

Sharp, hooked protuberances for tearing fish scales
Broad, flat protuberances for grinding and compacting algae
Combination of pointed and flattened protuberances for crushing snail shells

Endemic

Species that live nowhere

Functions of specialized tooth structures in fish

Crush snails, tears fish scales, compacts algae

Incomplete digestive tract (gastrointestinal tract and alimentary canal)

One opening for ingestion and excretion

Common parts
Testicles: Capturing prey
Mouth: Ingests food & eliminates wastes
Pharynx: (throat) Transports food
& wastes
Gastrovascular cavity: Site of digestion and absorption

The digestive tract organs

Mouth: Site mechanical and chemical processing

Esophagus: Transfers food

Stomach: Site of mechanical and chemical processing (digests proteins)

Small intestine: Site of chemical processing and absorption (digests proteins, fats, carbohydrates; absorbs nutrients and water)

Large intestine Absorbs water and forms feces; contains symbiotic bacteria
Appendix: Contains immune tissue; harbors symbiotic bacteria
Anus: Eliminates feces

Accessory organs in digestive tract

Salivary glands: Secretes molecules that aid in fat digestion Secrete enzymes that digest carbohydrates; supply lubricating mucus Liver: Secretes molecules that aid in fat digestion Gallbladder: Stores secretions from liver; empties into small intestine Pancreas: Secretes enzymes & other materials into small intestine

Salivary amylase

Begins breakdown of carbohydrates

Chief cells

Secrete inactive pepsinogen that converted to pepsin in presence of HCI Pepsinogen is important because it prevents destruction of proteins where enzyme is synthesized

Parietal cells

Source of HCI in gastric juice

2 functions of HCI

Activates the pepsin Denatures proteins to aid in their digestion

Mucous cells

secrete mucus; lines gastric epithelium & protects stomach from damage by HCl

Bicarbonate ions

Secreted into small intestine by pancreas and neutralizes acid arriving from the stomach

Villi

Makes up the surface of the small intestine, allows for high surface area of absorption Contains microvilli, and each villus has a blood and lymphatic vessels (lacteal) that absorb nutrients and transports them to the body systems

Proteases

Enzymes in small intestine that complete digestion of polypeptides to monomers- amino acids

Process of protein digestion

Begins in the stomach by pepsin (breaks peptide bonds between proteins) In the small intestine, proteases breaks completes the digestion of them proteases arrives in inactive form from pancreas where it is activated by enterokinase in small intestine. Enterokinase activates an inactive type of proteases called trypsinogen and converts it to trypsin Trypsin activates other enzymes secreted by the pancreas

Enzymes that pancreas produces for lipids and DNA/RNA digestion

Nucleases for digestion of DNA/RNA Pancreatic amylase for continued digestion of carbohydrates

Bile salts

Synthesized in liver and stored in gallbladder Emulsifies hydrophobic fats that arrive in large globules by to small intestine

Pancreatic lipase

Breaks chemical bonds in fats

Cecum

Outpocketing in digestive tract that starts at the large intestine Used to be a fermentation chamber for processing cellulose Presently functions in combating harmful bacteria and viruses and stores symbiotic bacteria into the appendix It is now considered a vestigial organ that lose its ancestral function

How are water and nutrients absorbed by the small intestine

Nutrients brought into epithelium through active transport, water follows passively through osmosis

Functions of large intestine

Compact wastes that remain– Absorb enough water (via aquaporins) to form feces This occurs in colon (largest part of the large intestine

Rectum

Final section of large intestine where feces is held

Main component of gastric juice

Water is the primary component of many secretions, including gastric juice.

When food is plentiful, animals tend to store most of what they eat as fat. Why is it like this?

Fat contains more than twice the energy per gram as protein or carbohydrate, so fat storage minimizes the energetic cost of carrying stored food energy.