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
In humans and other vertebrates fat digestion is facilitated by bile salts which act as detergents that break apart fat and lipids globules. Bile salts are a major component of bile
What is bile?
Bile is a mixture of substances that is produced in the liver and stored in the gallbladder. It enables formation of fat droplets in water as an aid in digestion and absorption of fats.
What is a liver?
This is a large internal organ in vertebrates that performs diverse functions such as producing by maintaining blood glucose level and detoxifying poisonous chemicals in the blood.
What is the list of water 💧 soluble vitamins?
B1( Thiamine) B2(Riboflavin) B3(Niacin) B5(Pantothenic acid) B6(Pyridoxine) B7(Biotin) B9(Folic acid) B12(Cobalamin) C(Ascorbic acid)
What is the list of fat soluble vitamins?
K(Phylloquinone)
A(Retinol)
D
E(Tocopherol)
What is the major dietary source, major functions in the body and symptoms of deficiency of vitamin B1 (Thiamine)?
Pork, legumes, peanuts, whole grains
Coenzymes used in removing CO2 in organic compounds.
Beriberi(tingling, poor coordination, reduced heart function)
What is the major dietary source major functions in the body and symptoms of deficiency of vitamin B2(riboflavin)?
Dairy products meats and grains and vegetables
Component of coenzyme fad and fmn
Skin lesions such as cracks at corners of mouth skin
What is the major dietary source major functions in the body and symptoms of deficiency of vitamin B3 (niacin)?
Nuts meats and grains
Component of coenzyme NAD+ and NADP+
Skin and gastro intestinal lesions delusions confusion
What is the major dietary source major function in the body and symptoms of deficiency of vitamin B5 pentothetic acid?
Which dairy products whole grains fruits and vegetables
This is a component of coenzyme A
Fatigue numbness tingling of hands and feet
What is the major source the major function and the symptoms of deficiency of vitamin B6 pyridoxine ?
Meats vegetables whole grains
Coenzyme used in amino acid metabolism
Irritability convulsions muscular twitching anaemia
What is a major dietary source major function and symptoms of deficiency of vitamin B7 biotin
Legumes other vegetables meats
Coenzyme in synthesis of fat ,glycogen and amino acids
Scaly skin inflammation neuromuscular disorders
For vitamin B9 folic acids
what are the major dietary sources major functions in the body and symptoms of deficiency?
Green vegetables are rangers nuts legumes whole grains
Coenzyme a nucleic acid and amino acid metabolism
Anemia neural tube malformation in foetus
4 vitamin B12 cobalamin
What is Earth’s major dietary source it’s functions in the body and the symptoms of deficiency?
Meat eggs and dairy products
Production of nucleic acid and red blood cells
Anaemia numbness and loss of balance
Call vitamin c ascorbic acid
What are the major dietary sources major functions in the body and symptoms of deficiency?
Citrus fruits broccoli and tomatoes
It is used and collagen synthesis it is also an antioxidant
Degeneration of skin and teeth delayed wound healing
For vitamin A retinol
What is the major dietary source the major function in the body and symptoms of deficiency of the vitamin
Dark green and orange vegetables and fruits and also dairy products
component of visual pigments and maintenance of epithelial tissue
Blindness skin disorders impaired immunity
Vitamin D
The usual
Daily products egg yolk
Aids in absorption and use of calcium and phosphorus
We are talking of rickets in children and Bones softening in adults
Vitamin e
The usual
Vegetable oils nuts and seeds
Antioxidant and helps prevent damage to cell membranes
Nervous system degeneration
Vitamin K
Green vegetables tea
Important in blood clotting
Defective blood clotting
The stomach has three muscle layers namely longitudinal circular and the inner oblique muscles.
What role do these muscle layers play in the stomach?
They are for mechanical digestion
Ingested food plus gastric juices is called chyme.
Rugae (gastric folds) role in the stomach
Allow stretch
Explain why the stomach does not digest itself is it has a very low pH.
The stomach lining consists of surface mucous cells which secrete a thick coat of mucus. The layer of epithelial tissue that is in contact with the hydrochloric acid is covered in a thick coat of mucus with epithelial tight junctions and I frequently replaced. There is also a mucus bicarbonate barrier between the hydrochloric acid and the epithelial lining of the stomach which neutralizes the acid.
The small intestine is the site of the greatest amount of digestion and absorption. It is the longest compartment which is 6 m in length.
What does the small intestine consist of?
Duodenum
Jejunum
Ileum
What is the duodenum?
This is a part of the small intestine after the stomach what is 25 cm. This is where I’m from stomach mixes with digestive juices from accessory glands
What are the three accessory glands?
Pancreas
Liver
Gallbladder
Bile does not contain enzymes
What is the function of the bile in the digestive system?
Neutralize and a pH of 8 and dilute content from the stomach. Bile creates optimal pH for pancreatic enzymes
BILE consists of water bile salt and fats and hence it emulsifies fats increasing the surface area for lipase action.
What does pancreatic juices consist of and what is its function in the human digestive system?
Pancreatic juices contain water, bicarbonate ions, and digestive enzymes.
Bicarbonate ions neutralize acidic chyme and provide optimal environment for pancreatic enzymes. This happened
The pancreas secretes digestive enzymes into the duodenum.
Proteases are released in an inactive form called zymogens
Trypsinogen is released from the duct and is activated. What activates the trypsinogen?
The trypsinogen is activated by the enterokinase( an enzyme found in the enterocytes) to trypsin.
Explain how other zymogens are changed into their activated forms from the enterokinase.
The enterokinase activates the trypsinogen to trypsin.
Trypsin then triggers the chymotrypsinogen to be in it’s activated for Chymotrypsin.
Trypsin also triggers the Procarboxypeptidase to be in it’s activated form that is Carboxypeptidase.
Absorption in the small intestine
Large folds in intestine finger-like projections, villi. T
….
The arrival of chyme in the duodenum triggers the release of secretin, which stimulates the pancreas to secrete bicarbonate
What is the function of the bicarbonate?
Bicarbonate neutralizes to e acidity of chyme and acts as a buffer for chemical digestion in the small intestine.
What advantage does the folds villi, and microvilli provide of the stomach?
They increase the surface area of the stomach up to 300 meters squared, hence increasing the rate of nutrient absorption.
How is fructose moved/ absorbed compared to other nutrients suh as amino acids, glucose molecules etc?
Fructose moves by facilitated DIFFUSION ( PASSIVE TRANSPORT) down it’s concentration gradient from the lumen of the intestines to epithelial cells.
Other nutrients are being pumped against their concentration gradient(ACTIVE TRANSPORT)
What is the hepatic portal vein?
This is a large blood vessel that conveys nutrient laden blood from the small intestine to the liver…this regulates the blood and nutrient content
Although many nutrients leave the small intestine to the bloodstream and pass through the liver for processing some products of fat digestion take a different path.
Explain this different path.
Hydrolysis of fats by lipase in the small intestine generates fatty acids and a monoglyceride(glycerol joined to a fatty acid). These products are absorbed by epithelial cells and then combined into triglycerides. They are then coated with phospholipids cholesterol, hence forming globules called CHYLOMICRONS.
Define CHYLOMICRON
A lipid transport globule composed of fats mixed with cholesterol and coated with proteins.
Maltase is a disaccharidase.
What does it break down?
It breaks down maltose into monosaccharides glucose.
Lactase is a disaccharidase
What does it break down
It breaks down lactose into galactose and glucose.
Sucrase is a dissacharidase
What does it break down
It breaks down sucrose into glucose and fructose.
What breaks down polypeptides into amino acids?
Peptidases(dipeptidase, Carboxypeptidase and aminopeptidase) which are membrane bound
Explain the process of nucleic acid(DNA) digestion
DNA is brokendown by NUCLEASE to form nucleotides
Nucleotides are further brokendown by nucleotidase into nucleosides
Nucleotidase breaks down nucleosides into… (a pentose sugar)
Explain how the hepatic portal vein works in 4 steps
- Products of digestion( sugars and amino acids) are absorbed within capillaries within the villi of the small intestine.
- Digested food molecules then travel through the hepatic portal vein s to the liver.
- The liver monitors and detoxifies blood content and maintains metabolic homeostasis.
- Hepatic veins deliver blood to the circulatory system…
Explain the abso3”3 rption of fats.
- Bile salts in duodenum emulsify lipids
- Digestion of fat by pancreatic lipase Yields free fatty acids and monoglycerides.
- Fatty acids and monoglycerides are absorbed through really wire missiles and reform into triglycerides.
- Triglycerides combined with cholesterol protein and phospholipids to form chylomicrons (lipoproteins)
- Chylomicrons leave epithelial cells by exocytosis and enter lacteals, where there carried away by the lymph.
Describe how the hormonal control of digestion occurs.
- As food enters the stomach, it stretches the walls of the stomach which triggers the release of the hormone gastrin. Gastrin stimulates the production of more Gastrin.
- As the food moves from the stomach to the duodenum, the duodenum responds by releasing digestive hormones CHOLECYSTOKININ(CKK) and SECRETIN. CKK stimulates the release of digestive enzymes from the pancreas and of bile from the gallbladder. Secretin stimulates the pancreas to release bicarbonate, which 🙂neutralizes😉chyme.
If the chyme is rich in fats, the secritin and CKK inhibit peristalsis. This slows down the movement of chyme and allows the small intestine to digest the fats(which is a time consuming process)
Blood glucose level relies on 2 hormones, insulin and glucagon.
What role does insulin play?
Secreted by The pancreatic beta cells, insulin promotes the uptake of glucose by most of the body cells.
What does Glucagon do in the glucose homeostasis?
Secreted by the pancreas, it promotes the release of Glucose into the blood from energy stores, such as Liver glycogen, increasing the blood concentration concentration.
What do alpha cells secrete?
Glucagon
What do beta cells produce?
Make insulin
What is diabetes mellitus
An endocrine disorder marked by the inability to maintain to glucose homeostasis.
Treatment requires daily insulin injections. Hey
Whats the function of Ghrelin?
Triggers the feeling gif hunger before meals
What’s the function of PYY?
Together with insulin, PYY suppresses appetite.
What is the function of Leptin?
A hormone produced by Adipose(Fat) tissue, also suppresses appetite.
