Nutrition in Humans (chap5) Flashcards
Ingestion
Food is taken into the body.
Digestion
Large food molecules are broken down into smaller, soluble molecules that can be absorbed by the body.
Assimilation
Nutrients are used by cells for maintenance of the body.
absorbed food substances are converted into new protoplasm.
For example: to provide energy or for making new protoplasm for growth
Egestion
Undigested matter is removed from the body.
Absorption
Nutrients are moved from the intestines into the bloodstream.
For example, to provide energy or for making new cytoplasm for growth.
nutrition
is the process by which organisms obtain food and energy for growth, repair & maintenance of the body.
human digestive system consists of;
gut or alimentary canal & organs (liver/gall bladder/pancreas) associated with it
alimentary canal
(from? to?)
mouth to anus
teeth
break up large pieces of food into smaller pieces.
chewing increases surface area to volume ratio of food so enzymes can act on it more efficiently.
salivary glands
secrete saliva into the mouth
Tongue
Helps in mixing of food with saliva and moving the food to the back of the mouth during swallowing
break up
physical process
eg: emulsidification/chewing
break down
digestion
chemical process involving enzymes
the Pharnyx
connects the buccal cavity to the oesophagus & the larynx (voice box)
the Pharnyx
connects the buccal cavity to the oesophagus & the larynx (voice box)
the Oesophagus
narrow, muscular tube that joins mouth to stomach.
muscle contact & relax to move food along the tube
the stomach
a distensible muscular bag.
Thick and well-developed muscular walls.
the inner surface if the stomach wall has numerous pits that open to gastric glands.
gastric glands
secrete gastric juice.
contains hydrochloric acid and protease.
pH 2, which gives an acidic environment that is optimal for protease to digest proteins.
the small intestine
absorbs water and nutrients from food.
lining of small intestine contains glands that secrete digestive enzymes such as maltase, lipase & intestinal protease.
constsists of: duodenum, illeum
ileum
inner surface of ileum is folded extensively & has numerous finger-like projections called villi. (singular villus)
this increases rate of absorption of digested food, mineral salts & most of the water into the bloodstream.
the large intestine
absorbs 90% of remaining water & remaining salts.
consists of: colon, rectum & anus
plays a role in the egestion of undigested & unabsorbed nutrients from the body
rectum
a short muscular tube.
temporary stores undigested food material as faeces.
when contracts, faeces are expelled through anus.
the Liver
largest gland in the body.
attached to 3 blood vessels: hepatic portal vein, hepatic vein, hepatic artery.
Liver cells produce & secrete bile.
bile
aids in the physical digestion of fats through emulsidification
alkaline, greenish-yellow liquid contaning bile salts.
does not contain enzymes
hepatic portal vein
carries blood containing absorbed nutrients from walls of small intestine, blood capillaries converge to form the hepatic portal vein, carries blood to liver
hepatic vein
carries deoxygenated blood away from liver (back to the heart)
hepatic artery
carries oxygenated blood from small intestine to liver