Nutrition Flashcards
Herbivores
Animals that only eat plant materials
e.g. Sheep, cattle and rabbits
Different groups of animal according to what they feed on
- Herbivores
- Carnivores
- Omnivores
Carnivores
- Animals that only eat other animals
- e.g. Cats, hyenas and lions
Omnivores
- Feed on both plant and animal matter
- e.g. Humans, pigs and baboons
Specific arrangement of teeth for a specific food source
Dentition
Four main types of teeth
- Incisors
- Canines
- Premolars
- Molars
Structure and function of incisors in humans
Chisel shaped for biting off pieces of food
Structure and function of canines in humans
Slightly longer than incisors with a point for biting and tearing off pieces of food
Structure and function of premolars in humans
- Have one or two blunt points (cusps)
- Used to chew or crush food into small pieces
Structure and function of molars in humans
- Larger than premolars, they have four or more blunt points (cusps)
- used to chew or crush food into small pieces
Herbivore lifestyle
- Spends most of the time grazing low energy foods
- No active chasing of prey
- Smaller herbivores need to escape predators
Carnivore lifestyle
- Very active when hunting and chasing prey
- Very inactive between hunts
Omnivores
- Relatively more active than herbivores
- Often opportunistic feeders
Dentition of a herbivore
- Sharp incisors for chopping vegetation
- Often canines absent and a large gap between incisors and molars
- Large flat premolars and molars for grinding food
Dentition of a carnivore
- Pointed incisors for tearing meat
- Long elongated canines for gripping and puncturing prey
- Sharp strong premolars and molars for crunching small bones
Dentition of an omnivore
- Chisel shaped incisors for biting
- Canines for tearing
- Flatter premolars and molars for grinding and crushing
Ingestion
The intake of food through the mouth
Digestion
The mechanical and chemical breakdown of food
Absorption
The diffusion of simple food molecules through the intestinal wall into the blood
Assimilation
Incorporation of nutrients shuch as amino acids and glucose into the cells
defecation / egestion
The removal of undigested and unabsorbed waste from the body through the anus in the form of faeces
Structure and function of the parts of the mouth
- Teeth (mechanically break up food)
- Tongue (tasting, helps push food under teeth and to form food bolus)
- Hard and soft palate (roof of mouth)
- Stratified epithelium (lines mouth)
- Salivary glands (provides saliva)
- Uvula (closes off the nasal passage during swallowing)
Structure and function of pharynx
Pharynx (throat) leads to the oesophagus (gullet) and trachea (windpipe)
intersection of nasal passages and alimentary canal
Epiglottis (closes over the opening to the trachea)
Structure and function of the oesophagus
Muscular tube (joining pharynx to the stomach) Lined with stratified epithelium (thick and layered) Muscles (peristaltic action to move food quickly to stomach)
Structure and function of the stomach
-Bag-like structure (holds undigested food) -Walls very thick and muscular (muscles contract to mechanically mix and churn food) -cardiac sphincter closes opening to oesophagus (prevents reflux) -pyloric sphincter closes opening to duodenum (regulates chyme movement into duodenum)
Structure and functions of small intestine
-Duodenum, jejunum and ileum -Multilayered walls: mucosa, submucosa, circular muscles, longitudinal muscles and serosa -Mucosa lined with columnar epithelium arranged in villi (increase surface area) -Bile and pancreatic duct enter into duodenum (enzymes in an alkaline medium to neutralise acid) -Ileum enters large intestine through ileo-caecal valve (one way movement)
Structure and function of large intestine
Caecum, (appendix), colon and rectum Secretes mucous to help with defaecation Water and mineral salts absorbed Undigested faeces temporarily stored before defaecation
Accessory organs of the alimentary system
Salivary glands Liver Pancreas Gall bladder
General tissue structure of the wall of the alimentary canal
Serosa (outermost, connective tissue) Muscle layer (longitudinal then circular muscles) Submucosa (vascular layer) Mucosa (inner layer, epithelial)
Functions of liver
Produce bile -Makes and store glycogen from glucose -Releases glucose when body needs it -Deanimation of excess amino acids -Detoxification organ- processes many toxins like alcohol -Regulates lipids in the body - excess glucose converted to fat and transported to storage
Functions of gall bladder
-when stimulated, it contracts and releases stored bile -bile duct connects with pancreatic duct and enters duodenum
Exocrine gland
Secretions secreted into a duct to be carried where needed
Endocrine gland
No duct used, secretions directly into the blood and thereby carried to target areas of the body
Functions of the pancreas
Endocrine gland: secretes insulin and glucagon Exocrine gland: secretes pancreatic juice when food enters duodenum
Two types of digestion
Mechanical digestion Chemical digestion
Adult human dental formula
2.1.2.3 ——– 2.1.2.3 (On both top and bottom on one side of the jaw there are 2 incisors, 1 canine, 2 premolars and 3 molars)
Swallowing
Bolus formed by tongue as food is chewed and moistened Bolus pushed into pharynx by tongue Food stimulates nerves in walls of pharynx Swallowing reflex initiated, an involuntary action Food carried down oesophagus by peristalsis
Enzymes
-Protein molecules that act as biological catalysts -because they speed up biochemical reactions -they are specific to a particular substrate -they are affected by conditions like pH and temperature
Chemical digestion by hydrochloric acid
-Produced in stomach by glands in the wall -Softens food -Denatures proteins -Breaks down protein molecules -Kills potentially harmful bacteria
Main types of enzymes
Carbohydrases e.g. Amylase Proteases e.g. Pepsin Lipases e.g. Lipase
Carbohydrases e.g. amylase
Found in mouth and small intestine Acts on carbohydrates to eventually form glucose Prefers an alkaline pH
Proteases e.g. pepsin
Found in stomach and small intestine Acts on proteins to eventually form amino acids Prefers an acidic pH
Lipases e.g. lipase
Found in small intestine Acts on lipids to form fatty acids and glycerol Prefers a neutral pH
Deck incomplete
To come: absorption, assimilation, homeostatic control, and health
