Human Digestive System Flashcards
heterotrophic
organisms that are not capable of making their own food
autotrophic
organisms capable of making their own food using energy
herbivore
eats plants only
carnivore
eats animals only
omnivore
eats both animals and plants
photosynthesis
plants use light energy to make food
chemosynthesis
use of chemical energy to make food
saprophytic (decomposers)
organisms that obtain their food from dead organisms
parasitic
two organisms of different species live together where one benefits and causes harm to the other
symbiotic
organisms that live in close contact with a second species and at least one organism benefits
egestion
removal of unabsorbed waste
excretion
removal of waste products of metabolism
peristalysis
rhythmic muscular contraction and relaxation in the wall of the alimentary canal causing the movement of food
deamination
breaking down excess amino acids to form urea in the liver
balanced diet
contains the correct amounts of each food type for good health
stages of nutrition
ingestion: taking in food
digestion: physical and chemical break down of food into smaller molecules
absorption: food diffuses into the bloodstream
egestion: removal of unabsorbed waste
types of digestion
mechanical: physical break down
chemical: addition of digestive enzymes
why is digestion necessary
to make food soluble
easier to absorb/transport
mouth
chemical: salivary glands produce saliva, amylase breaks down starch
physical: teeth, tongue
type and function of teeth
incisors: cutting
canines: gripping and tearing
molars: crushing and grinding
premolars: crushing and grinding
oesophagus
mechanical: peristalsis to move food from mouth to stomach
stomach
location: abdominal cavity
mechanical: food churned to chyme
chemical:
digestive function - digestive enzymes break down food
defence function - hydrochloric acid and lysozyme produced to kill bacteria
gastric juice
site of production: stomach functions: mucous: lines and protects stomach wall HCI: kills bacteria, converts pepsinogen to pepsin pepsin: breaks down proteins
pancreas
location: abdominal cavity, below the stomach
functions:
digestive function: produces lipase,amylase
defence function: produces insulin
digestive function can be called
exocrine function
defence function can be called
endocrine function
liver
location: above the stomach, upper abdomen
functions:
-makes bile
-helps detoxify the body
- deamination
-converts glucose to glycogen for storage
-stores vit and minerals
bile
composition: water, bile salts, bile pigments
functions:
-emulsify fats
-neutralise chyme from stomach to provide optimum pH for enzymes
gall bladder
location: liver
functions:
-stores bile
-releases bile into the duodenum through the bile duct
small intestine
parts: duodenum, jejenum, ileum
functions: digestion and absorption
duodenum function
chemical digestion using lipase and amylase
ileum functions
absorb nutrients into bloodstream by diffusion
ileum adaptations for absorption
- long tube - allows time for reabsorption
- villi - infoldings which increase the surface area available for reabsorption
- walls are one cell thick - allows substances to diffuse easily into bloodstream
how fat is absorbed from the small intestine
- fatty acids and glycerol are absorbed into the lacteal
- re form into fats
- diffuse into bloodstream through blood vessels
- peristalsis occurs at muscular wall
hepatic portal vein
only vein not connected directly with the heart
connects ileum with liver
transports amino acids, glucose to the liver
amino acid broken down to urea
urea leaves the liver through hepatic vein
large intestine/colon parts
caecum
appendix
rectum
functions of large intestine
- reabsorbs water
- symbiosis:
- bacteria feed on waste to produce vit B & K
- break down cellulose, return nutrients to small intestine
benefits of fibre
prevents constipation by stimulating peristalsis in colon
constipation
too much water reabsorbed when undigested food moves too slowly
amylase
produced in: salivary glands/pancreas
secreted to & active in: mouth/duodenum
pH: 7-9
role: digest starch -> maltose
pepsin
produced in: stomach
secreted to & active in: stomach
pH: 2
role: digest protein -> peptides
lipase
produced in: pancreas
secreted to & active in: duodenum
pH: 7-9
role: digest fats -> fatty acids and glycerol
seven components of a healthy diet
carbs proteins fats vitamins minerals water fibre
food requirements depend on
age
gender
health and activity levels
