Chapter 41 Flashcards
Two requirements of animals
Chemical energy from ATP
Carbon-containing molecules
What are the 4 processes of obtaining energy from food
Ingestion
Digestion
Absorption
Elimination
How many amino acids can be made from the human body
12 of the 20
Minerals
Important cofactors or structural materials (Ca, Fe, MG, etc)
What are vitamins
Organic compounds vital for health in minute amounts
Electrolytes
Inorganic ions that influence osmotic balance; required for normal membrane function
Digestive tract
Comes in two general designs
adaptive radiation
Diversification of a single ancestral lineage into many species, each of which lives in a different habitat or emplys distinct feeding method
Complete digestive tracts
Have two openings - mouth for ingestion and anus for elimination of wastes
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
Where do chemical digestion of carbohydrates and lipids begin in?
mouth due to salivary amylase and lingual lipase attacking it
Where do the chemical digestion of proteins occur?
stomach due to pepsin
Where does digestion mostly occur in humans
Small intestine due to receiving digestive enzymes from pancreas and bile from liver
What is the primary function of the small intestine
To better absorb nutrients
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.
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.
What enzyme performs majority of chemical digestion of lipids
Pancreatic lipase
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.
