Nutrition And Digestion Flashcards
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What must an adequate diet satisfy?
- Chemical energy for cellular processes.
- Organic building blocks for macromolecules.
- Essential nutrients.
Definition of NUTRITION.
The process by which an organism takes in and makes use of food substances.
Essential nutrient definition.
A substance that an organism cannot synthesize from any other material and therefore must absorb in preassembled form.
What are the roles of essential nutrients? Vitamins Minerals mino acids Fatty acid
Vitamin-source of coenzyme NADH- Vitamin B3 Mineral-cofactor-Iron Prostaglandins--used in cell signaling Phospholipids--cell membrane components Linoleic acid--substrate of enzymes
What is an essential amino acid?
°°°°°°°°°✓An amino acid that an animal cannot synthesize itself and must be obtained from food in prefabricated form.
Adult humans require 8 amino acids in their diet.
What are these 8 amino acids?
Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine
Animals require fatty acids to synthesise of variety of cellular components including membrane phospholipids signalling molecules and storage facts. Animals can synthesize many fatty acids they lack the enzymes to form the double bonds found in certain required fatty acids instead these molecules must now be obtained from the diet and are considered essential fatty acids
What are essential fatty acids?
Essential fatty acid is an unsaturated fatty acid that an animal needs but cannot make.
Highlight unsaturated.
Define VITAMIN
A vitamin is an organic molecule required in the diet in very small amounts many vitamins serve as coenzymes over parts of coenzymes.
There are fat-soluble vitamins
There are water-soluble vitamins
What are the 4 stages of food processing?
Ingestion
Digestion
Absorption
Elimination
What is Ingestion?
The stage of food processing in animals: the act of eating
There 4 main feeding mechanism of animals
Describe all 4
Filter feeding– food particles are filters from the surrounding medium.
Substrate feeding– substrate feeders are animals that live in or on their own food. Eh. Catapillar
Fluid feeding—suck nutrient-rich fluid from a living host.
Bulk feeders– humans are bulk feeders– they eat relative large pieces of food.
What is digestion?
The second stage of food processing in animals, the breaking down of food molecules into molecules small enough for the body to absorb.
During digestion, both the mechanical and chemical processes are required.
Explain these processes.
Mechanical processes include chewing the food into smaller pieces, increasing the surface area of the food.
Chemical Digestion cleaves large molecules into smaller components. Chemical Digestion is necessary because animals cannot directly use the proteins, carbohydrates, nucleic acids, days and phospholipids in food. These molecules are too large to pass through cell membranes and hence are broken down even further.
What is absorption?
The third stage of food processing in animals: the uptake of small nutrient molecules by an organism’s body
What is elimination?
The 4th and final stage of food processing in animals, the passing out of undigested material out of the body.
Define and explain Intracellular Digestion.
The hydrolysis(breakdown) of food inside vacuoles, after a cell🌕 engulfs solid food through phagocytosis or liquid food through pinocytosis.
Define a Gastrovascular Cavity?
A central cavity with a single opening in the body of certain animals, including cnidarians and flatworms, that functions in both the digestion and distribution of nutrients.
E.g. Cnidarians
Explain digestion in a hydra
The hydra uses its tentacles to stop captured prey through its mouth into its gastrovascular cavity. Specialised plant cells of hydras gastrodermis the tissue layer that lines the committee that secrete digestive enzymes that break the soft tissues after prayer into tiny pieces.
- Digestive enzymes are released from gland cells
- Enzymes break food down into small particles
- Food particles are engulfed and digested in food vacuoles.
What is the definition of An ALIMENTARY CANAL?
An alimentary canal is a complete digestive tract consisting of a tube running between a mouth and an anus
What are salivary glands?
It’s a gland that is associated with the oral cavity that secrete substances that lubricate food and begin the process of chemical digestion..
Saliva contains a large amount of the enzyme amylase
Define amylase..
Amylase is an enzyme that hydrolyzes starch and glycogen into smaller polysaccharide and the disaccharide maltose
Within the oesophagus food is pushed along by peristalsis
Define peristalsis.
Alternating waves of contraction and relaxation in the smooth muscles lining the alimentary canal that push food along the canal.
What is the function of mucous cells?
To secrete mucus, which lubricates and protects the cells lining the stomach(because the stomach has a very low pH=2)
What is the function of chief cells?
Secretes pepsinogen, an inactive form of the digestive enzyme pepsin.
What is the function of parietal cells?
To produce the components of hydrochloric acid.
Explain the production of gastric juice in the 3 steps.
- Pepsinogen and HCl are introduced into the lumen of the stomach.
- HCl converts pepsinogen to pepsin.
- Pepsin then activates more pepsinogen, starting a chain reaction. Pepsin begins chemical digestion of proteins.
Define chyme
°°°°The mixture of partially digested food and digestive juices formed in the stomach.°°°°
What are the 2 major roles that the stomach holds?
- Storage of food–can hold up to 2L of food and liquid.
2. To process food into a liquid suspension.
Define a PROTEASE
An enzyme that digests proteins by hydrolysis.
Unlike most enzymes pepsin is adapted to work in a very acidic environment
Define pepsin
An enzyme present in gastric juice that begins the hydrolysis of proteins.
By breaking peptide bonds in cleves proteins into smaller polypeptides and further exposes the contents of ingested tissues
Most enzymatic hydrolysis of macromolecules from food occurs in the small intestine
What is the small intestine?
Long section view elementary canal, the principal site of enzymatic hydrolysis of food macromolecules and the absorption of nutrients.
The first 25 cm of the small intestine forms the duodenum
What Is the duodenum?
The first section of the small intestine where came from the stomach mixes with digestive juices from the pancreas liver and gallbladder as well as from plant cells of the intestinal wall.
The arrival of chyme in the duodenum triggers the release of hormones secretin which stimulates the pancreas to secrete bicarbonate.
What is the pancreas?
A gland with exocrine and endocrine tissues the endocrine portion functions and digestion secreting enzymes and an alkaline solution into the intestine via duct, the dark less endocrine portion functions in homeostasis secreting the hormones insulin and glucagon into the blood