Are we what we eat - Week 3

Question 1

List the major parts of the digestive system and describe the function of each part.

Answer 1

Oral cavity –Through mastication food is broken down and chemical digestion begins with the introduction of saliva.
Pharynx (throat) – a bolus of food and drink is brought from the oral cavity to the Esophagus. The Uvula (soft palate) in the pharynx prevents food and drink from entering the nasopharynx.
Esophagus – Brings food and drink from the pharynx to the stomach. Epiglottis prevents food and drink entering trachea.
Stomach – Is a holding and digestion point for food. Muscular contractions, hydrochloric acid and protein digesting enzymes process food and drink received from the oesophagus turning it into chyme (pronounced kyme), ready for the intestines
Small intestine –Further breakdown from enzymes in the duodenum, jejunum and ilium. Mucus in the duodenum neutralises acid. Jejunum major function is nutrient absorption. Overall water absorption
Large intestine – Water and sodium chloride absorption. Synthesis of vitamin B & K also occurs. Faeces is created.
Anal canal – Exit point

Question 2

List the basic histological layers of the digestive tract.

Answer 2

Mucosa: inner most layer
Submucosa: connective tissue layer, contains blood vessels, nerves etc
Muscularis: 2/3 muscle layer
Seerosa/Adventitia: outermost layer, connective tissue, stability

Question 3

List the accessory organs of the digestive system and describe their role.

Answer 3

Liver – Makes bile which enters the duodenum aiding in the break down of lipids into smaller particles. Also filters nutrients in blood coming from the intestines, stores energy and detoxifies harmful substances.
Gallbladder – Stores and concentrates bile from the liver in preparation for release into the duodenum
Pancreas – Has a hormonal (endocrine) function. Produces enzymes (Endocrine (hormonal) function, produces insulin and glucagon. Exocrine function (substance created which then exits via duct system), produces enzymes which are releasted via ducts into duodenum system. Enzymes break down macromolicules in the duodenum

Question 4

State what contribution the liver, gallbladder and pancreas make to digestion

Answer 4

Liver – makes bile which enters via gallbladder to duodenum and works on breaking down larger droplets of lipids to smaller ones so that digestive enzymes can emulsify lipids more effitiently.
Filters nutrient rich blood coming from intestines, stores energy (glucose as glycogen, lipids).
Detoxification of drugs
Gallbladder – Stores and concentrates bile before moving to duodenum, helping to emulsify lipids.
Pancreas –Exocrine function (substance created which then exits via duct system), produces enzymes which are released via ducts into duodenum system. Enzymes break down macromolicules in the duodenum

Question 5

Explain the difference between digestion and absorption

Answer 5

Digestion – Breakdown of food into smaller particles (mechanical process) and breaks down bonds into a usable format(chemical process).
Absorption - is movement of nutrients and water of digestive tract back into body via the liver.

Question 6

Describe carbohydrates, lipids and proteins.

Answer 6

C: Sugars, come from plants (exept Lactose which comes from milk); Carbon, Hydrogen, Oxygen. Saccharides are the building blocks.
L: Carbon, hydrogen, oxygen; Insoluble/fats; for energy.
P: Animal product,; Carbon, hydrogen, oxygen hydrogen, sulfur. Amino acids are the building blocks. Carry oxygen around the body, making up connective tissue, cell membrane transport, hormones enzymes made of this, broken down lower in digestive system

Question 7

Have an understanding of the relative recommended amounts of carbohydrates, lipids and proteins.

Answer 7

45-65% Carbs, 10-35% protein, 20-35% lipids. Percentage of each will vary according to the requirements of the body, ei puberty will require different percentage breakdown for optimal function in comparison to someone who is pregnant

Question 8

List the basic building blocks of carbohydrates, lipids and proteins.

Answer 8

C: Monosacharides, Disacharades, Polysaccharides
L: Glycerol, fatty acids
P: Amino Acids

Question 9

Distinguish between vitamins and minerals and state why they are needed by the body.

Answer 9

V organic (contain carbon) molecules/nutrients. Fat or water soluble only. Cant be self produced and required for normal metabolism function.
Minerals inorganic (no carbon). 2 categories major and trace. Can become components of co-enzymes, heamoglobin. Used to establish membrane potential, sets up potential changes in electrical signaling via neurons over the body. Both plant and animal based

Question 10

Describe the function of enzymes within the body.

Answer 10

Enzymes help bring together molecules, they increase the chemical reaction of molecules

Question 11

What are carbohydrates, lipids and proteins?

Answer 11

C: Sugars, come from plants (exept Lactose which comes from milk); Carbon, Hydrogen, Oxygen. Saccharides are the building blocks
L: Lipids break down into fatty acids which are then absorbed into the lymphatic system. Moved into the heart then into cardiovascular system. Don’t move into the blood directly like carbs and proten. Trigricerides, cholesterol,Phosopholipids, Eicosanoids. Used in plasma membranes, bile, myelin sheath (coating on neurons which increases transfer speed of information), signalling molecules (blood clotting, tissue repair, etc.)
P: Animal product; Carbon, hydrogen, oxygen hydrogen, sulfur. Amino acids are the building blocks

Question 12

What are vitamins and minerals and why are they needed?

Answer 12

Vitamins and minerals come in organic and inorganic form. Vitamins, found in fruit and vegetable, aid in metabolic functioning. They can be either fat or water soluble. Our body does not produce vitamins on its own. Minerals, also found in fruit and vegetable, aid with membrane potential setting up charge for neurons to transfer through the body. Can become a component of enzymes and heamoglobin

Question 13

What does the process of digestion do?

Answer 13

Enzymes are a protein catalyst, They increase the rate chemical reaction of protein molecules. There are different enzymes for different chemical reactions

Question 14

Name the structures of the digestive tract and name what is the major function of each structure?

Answer 14

Oral cavity – where ingestion begins. Through mastication food is broken down and saliva is introduced so that it food may enter the pharynx, where peristalsis and segmentation (bolus creation).
Pharynx (throat) – connection between the mouth and esophagus. The Uvula (soft palate) in the pharynx prevents food and drink from entering the nasopharynx.
Esophagus – Connects the Pharynx to the stomach. Epiglottis prevents food and drink entering trachea.
Stomach – holding point for food. Churns into chyme by introducing hydrochloric acid and protein digesting enzymes. Mucus help protect epitherial cells lining the stomach from the acid
Small intestine – Has 3 devisions, the Duodenum, Jejunum and Ileum. Further breakdown from enzymes. Mucus neutralises acid. Jejunum major function is nutrient absorption. Overall water absorption
Large intestine – Water absorption and sodium chloride absorption. Synthesis of vitamin B & K.
Anus – Exit point

Question 15

What are the accessory organs of the digestive system?

Answer 15

Ingestion - Occurs at the oral cavity moving through the pharynx and eosophagus
Digestion – Occurs from the stomach to the large intestine
Absorption – Occurs in the Intestines, greatest nutrient absorption occurring in the jejunum
Elimination - Occurs through the rectum and anal canal

Question 16

How are the products of digestion absorbed and where do they go?

Answer 16

Products are absorbed through Lacteals and Capillaries within villi and microvilli in the stomach. Nutrients are then transferred to the liver for use and any extra nutrients are further distributed through the blood stream where they are taken up by cells as needed and cells are distributed throughout the body where required

Question 17

How does the body use the products of digestion?

Answer 17

Macromolecules created through the digestive process are processed into cells ready to be distributed throughout the body for use where required. Carbohydrate is primarily used for energy. Proteins are used to regulate body function ie globular protein in haemoglobin, muscle proteins, cell membrane transport, enzyme work, hormone function and antibodies. Lipids are used for energy. Vitamins are essential for normal metabolism. Minerals are components of co-enzymes, some vitamins, haemoglobin and organic molecules. They establish membrane potential & action potential, gives strength in bones and teeth. Water is important for blood volume and pressure and maintaining homeostasis, ions only found in water are distributed throughout the body.