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Nutrition: The digestive and respiratory systems
NUTRITION: THE DIGESTIVE AND
RESPIRATORY SYSTEMS
Biology
Nutrition: The digestive and respiratory systems
© Oxford University Press España, S. A. Biology 2
• Human nutrition • The digestive system • The digestive process in the mouth • The digestive process in the stomach • The digestive process in the small intestine • Liver and pancreas • From food to nutrients • Food absorption • The digestive process in the large intestine • The respiratory system • Gas exchange • Pulmonary ventilation • Health and illnesses of the digestive system • Health and illnesses of the respiratory system
Nutrition: The digestive and respiratory systems
HUMAN NUTRITION
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Nutrition: The digestive and respiratory systems
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Digestive, respiratory, excretory and circulatory system all play a role in nutrition.
Digestive system
Respiratory system
Excretory system
Circulatory system
Nutrition: The digestive and respiratory systems
THE DIGESTIVE SYSTEM
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Nutrition: The digestive and respiratory systems
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salivary glands
pharynx
gall bladder
appendix
rectum
anus
mouth
esophagus
salivary glands
diaphragm
liver
stomach
pancreas
large intestine
small intestine
An inner cell layer called a mucous membrane makes up the gastrointestinal tract. It’s internally protected by a lubricant substance called mucus and it’s surrounded by muscular layers. When these layers contract they push food down the digestive tract. The mucosa in the stomach and intestine contain glands that secrete a protective mucous and others that secrete digestive juices.
Nutrition: The digestive and respiratory systems
THE DIGESTIVE PROCESS IN THE MOUTH
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Nutrition: The digestive and respiratory systems
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Salivation
parotid
submandibular
sublingual
premolars
incisors
Chewing
canines
molars
tongue
bolus
nasal pasages soft palate
epiglottis
larynx
pharynx
esophagus
Swallowing
Nutrition: The digestive and respiratory systems
THE DIGESTIVE PROCESS IN THE STOMACH
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Nutrition: The digestive and respiratory systems
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esophagus
cardia
layers of muscle
pylorus
Gastric juices contain pepsin, an enzyme that starts protein digestion, and hydrochloric acid, which has two functions. It activates pepsin enzymes and supports them by helping the disintegration of food fibres, and destroys bacteria that may be present in food.
The inner layer is covered in mucus that protects it from the effects of hydrochloric acid and enzymes.
The stomach is formed by three muscular layers, which perform massaging motions to mix the chyme.
Nutrition: The digestive and respiratory systems
THE DIGESTIVE SYSTEM IN THE SMALL INTESTINE
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Nutrition: The digestive and respiratory systems
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The small intestine releases digestive secretions with enzymes that break down different molecules. Stomach
Pylorus
Large intestine
Ileocecal valve
Duodenum Short section (25 cm) shaped like a horseshoe
Jejunum The longest part of the small intestine
Ileum The final section that ends in the large intestine
Nutrition: The digestive and respiratory systems
LIVER AND PANCREAS
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Nutrition: The digestive and respiratory systems
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The liver produces bile, which is stored in the gall bladder. Bile intervenes in the emulsification of fats: fats are transformed into very small drops, helping enzymes found in digestive juices break down fats.
The pancreas secretes pancreatic juice through the ampulla of Vater, which contains enzymes capable of digesting the different types of molecules present in foods.
stomach
pancreas
duodenum
ampulla of Vater
gall bladder
liver esophagus
Nutrition: The digestive and respiratory systems
FROM FOOD TO NUTRIENTS
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Nutrition: The digestive and respiratory systems
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Digested by
Digested by
Digested by
Digested by
Result in
Result in
Result in
Result in
Starch
Sucrose
Fats
Proteins
Amylase (s, i, p) Maltase (i)
Maltose
Glucose molecules
Sacarasa (i)
Lipase (i, p)
Pepsin (g) Tripsin (p) Erepsin (i)
Peptide Short peptide
Amino acids
Glycerine molecules and fatty acids
Fructose and glucose molecules
Foods Enzymes Nutrients
Nutrition: The digestive and respiratory systems
FOOD ABSORPTION
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Nutrition: The digestive and respiratory systems
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Food absorption refers to the passage of nutrients to our blood. This allows those nutrients to be distributed across the whole organism. It takes place mainly in the small intestine.
In order to increase the surface area for the absorption of nutrients, the inner layer is full of villi and intestinal folds, and the plasma membrane that forms villi has extra creases known as microvilli.
small intestine
intestinal folds
lymph capillary
intestinal gland
capillaries
intestinal vili
microvili
intestinal mucous cells
Nutrition: The digestive and respiratory systems
THE DIGESTIVE PROCESS IN THE LARGE INTESTINE
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Nutrition: The digestive and respiratory systems
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Absorption of most water and minerals takes place in the large intestine; faeces compact to form stools.
ileocecal valve
appendix
Rectum. This is the final section that ends in the anus.
anus
Colon. This part of the large intestine is where symbiotic bacteria of the intestinal flora develop and certain vitamins, such as B12 and K, are produced.
ascending colon
descending colon
Cecum. This is the first section, it’s shaped like a bag and has a narrow extension, the appendix.
Nutrition: The digestive and respiratory systems
THE RESPIRATORY SYSTEM
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Nutrition: The digestive and respiratory systems
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The respiratory system obtains oxygen from the air and provides it to the blood in the circulatory system. Blood carries the oxygen into the cells and takes away carbon dioxide so it can be released.
diaphragm
bronchiole
bronchi
left lung
epiglottis
pharynx
nasal cavity
larynx
trachea
right lung
heart
Nutrition: The digestive and respiratory systems
GAS EXCHANGE
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Nutrition: The digestive and respiratory systems
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Oxygen is exchanged between air and blood by the process of diffusion: oxygen travels from the area where its concentration is greater to the area where it is lower.
Oxygen concentration is higher in our alveoli than in our blood. Carbon dioxide concentration is lower in our alveoli than in our blood.
The oxygen found in air goes into the blood, after passing through the alveolar wall and the wall of the capillary, to be transported to the body's cells.
El dióxido de carbono de la sangre pasa a los alvéolos, donde se mezcla con el aire que contienen y es expulsado en la espiración.
O2
CO2
CO2
CO2
CO2
O2
O2
O2
air
pulmonary alveoli
pulmonary capillary
Nutrition: The digestive and respiratory systems
PULMONARY VENTILATION
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Nutrition: The digestive and respiratory systems
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Inspiration Expiration
Air enters Air exits
Ribcage increases its volume
The diaphragm contracts, flattens and lowers itself
Ribcage decreases its volume
The diaphragm relaxes, curves and rises
Nutrition: The digestive and respiratory systems
HEALTH AND ILLNESSES OF THE DIGESTIVE SYSTEM
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Nutrition: The digestive and respiratory systems
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Recommendations to look after the organs of the digestive system: • Chew food slowly, making sure that all food is crushed properly. • Brush your teeth after each meal in order to eliminate any small pieces of food. • Visit the dentist at least once a year. • Do not eat or drink foods that are very hot. • Wash your hands before eating or preparing food. • Do not eat out of meal times so that the digestive system doesn’t function non-stop. • Ensure foods you eat are in perfect condition in order to prevent food poisoning. • Eat foods that have fibre as they help intestinal movements. • Do not consume alcohol.
The illnesses of the digestive system can affect the mouth, like cavities or gingivitis; the stomach, like gastritis or ulcers; the liver, like hepatitis or cirrhosis, and the intestine, like gastroenteritis, appendicitis, constipation or colon cancer. ulcers
Nutrition: The digestive and respiratory systems
HEALTH AND ILLNESSES OF THE RESPIRATORY SYSTEM
© Oxford University Press España, S. A. Biology 29
Nutrition: The digestive and respiratory systems
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Recommendations to look after the respiratory organs: • Do not smoke. • Try to avoid sudden changes of temperature as such changes increase the risk of
contracting respiratory illnesses. • Do physical exercise regularly. • Try to avoid being in contact with dust and atmospheric contaminants. • Try to breathe through your nose.
Illnesses related to the respiratory system are caused by infections (infectious), like nasal catarrh, bronchitis or flu, or by an inflammation of the mucosa (non-infectious), like aphonia, asthma, emphysema or lung cancer.