Science

• carbohydrates - Body main source of energy. Together with proteins, carbohydrates also function as a structural component of living cells
• proteins - used in the synthesis of enzymes, hormones, and antibodies that combat diseases. they can also used as an energy source.
• amino acids - The building block of proteins. are essential in the formation of new protoplasm for growth and repair of worn-out body cells.
• 10 Essential Amino acid

  • Acids are arginine
  • Histidine
  • Metionine
  • tryptophan
  • Leucine
  • Phenlalanine
  • Threonine
  • Valine
  • Lysine
  • Isoleucine
• Fats - Also energy-providing foods. in fact, fats provide twice as much energy per gram as carbohydrates.
• Vitamins - are complex organic molecules needed in small amounts and cannot be manufactured by the human body.
• Fat-soluble vitamins - can be stored in the fats of the body
• water soluble vitamins - cannot be stored in the body and must be obtained by eating vitamin-rich foods.
• Minerals - Inorganic substances that do not provide energy but are important for different body functions. Some minerals are needed by the body in large amounts, while some are needed in small quantities.
• Trace element - minerals needed by the body in small amounts.
• Water - Humans can survive longer without food. humans and most mammals are made up of about 70 percent water.
• Nutrition - the consumption of food these sources and the processes that convert food substances into living matter.
• holozioc nutrition - mode of feeding found in animals.
• Ingestion - Intake of food through the mouth.
• Digestion - Process of mechanical and chemical breakdown, in which large food molecules are broken down into simpler molecules that can be absorbed by the body cells.
• Absorption - Digested food materials are absorbed by the body cells.
• Assimilation - transport and use of absorbed nutrients, such as the food's conversion into new protoplasm to provide energy.
• Elimination - removal of undigested material out of the digestive tract.
• Digestion - Food is broken down into nutrients through a process.
• Physical digestion - mechanical breakdown of food into smaller pieces. This occurs in the mouth when you chew food, and in the stomach where continual contractions and relaxation of the muscles in the stomach wall cause a churning action, which mixes and breaks down the food particles.
• Chemical digestion - breakdown of complex, such as proteins, starch, and fats, into simple soluble molecules through hydrolytic reactions catalyzed by digestive enzymes.
• Mouth - food intake starts in the ____, which leads to the mouth cavity.
• The jaws bear four types of teeth:

  • incisors
  • canines
  • premolars
  • molars
• taste buds - the tongue has special cells
• saliva - which opens into the mouth cavity via ducts, that release a secretation.
• mucin - in saliva helps to soften food, while chewing helps to break down food into smaller pieces.
• Pharynx - Common passage for food and air. it is the part of the gut that leads from the mouth to the esophagus and also to the trachea(windpipe) by way of the larynx (voice box).
• glottis - The larynx has a slit-like opening.
• epiglottis - a piece of flap-like cartilage.
• esophagus/gullet - after you swallow, smooth muscles force food into a narrow, muscular tube.
• peristalsis - these two layers of muscles cause rhythmic, wavelike contractions of the wall of the gut.
• stomach - the partially digested food now enters a j-shaped organ, which lies beneath the diaphragm and is partly covered by the liver. it has thick muscles in its wall.
• gastric juice - dilute solution of hydrochloric acid and pepsin
• pepsin - an active enzyme secreted by the cells of the gastric glands.
• chyme - the partially digested food becomes liquefied to form.
• pyloric sphincter - the stomach is connected to the small intestine by a muscular valve.
• food absorption - the process which digested food materials are absorbed by the cells.
• the small intestine consists of three parts:

  • duodenum
  • jejunum
  • ileum
• small intestine - about six meters long when stretched. like the stomach lining, the small intestine's wall lining also contains glands that secrete several digestive enzymes.
• villi - its inner lining is covered with millions of tiny fingerlike structures.