Le système digestif

• The digestive system ensures the digestion of food.
• It is composed of different organs including the mouth, salivary glands, esophagus, stomach, liver, pancreas, small intestine, large intestine, rectum, and anus.
• The organs through which food passes form the digestive tract.
• The digestive tract consists solely of the mouth, esophagus, stomach, small intestine, large intestine, and anus, where food passes through.
• The appearance of food changes as it moves through the organs of the digestive tract.
• Transformation begins in the mouth and is referred to as the food bolus.
• This process of transformation continues in the stomach and then in the small intestine, where the food becomes unrecognizable.
• In the large intestine, any remaining undigested material is absorbed by the body for excretion as feces.
• Food enters the mouth where it is chewed and mixed with saliva produced by the salivary glands, forming the food bolus.
• Then, the food bolus passes into the esophagus and reaches the stomach.
• Next, it enters the small intestine where digested food is converted into nutrients.
• Finally, undigested food enters the large intestine, forming excrement that is eliminated through the anus via a voluntary action.

Mechanical Action

• Borelli studied digestion in chickens.
• He gave chickens glass beads to eat.
• A few days later, he collected the excrement and observed crushed beads inside.
• Digestion is mechanical.
• The glass beads are churned in the chicken's stomach with the pebbles it swallowed.
• The beads are reduced into pieces.

Chemical Action

• Spallanzani believed that digestion also involves a chemical action.
• He proposed a scientific hypothesis.
• Food digestion relies on liquids produced by the digestive system's organs.
• He retrieved digestive liquid from his stomach and mixed it with meat in a glass tube.
• He left the mixture to sit for three days and noted a change in appearance.
• The meat in contact with the digestive liquid disintegrates and transforms into a mixture.
• Digestion comprises chemical action due to liquid substances in the digestive system's organs.
• Nutrients travel to the small intestine.
• Undigested food forms into excrement.
• Digestion involves mechanical action from teeth grinding food and chemical action in the stomach via gastric juices.
• Transformed food passes through organs of the digestive system.
• Transformed components consist of salivary glands, esophagus, stomach, small intestine, large intestine, anus.
• Digestion transforms food into nutrients.
• This is aided by digestive juices released by the digestive organs.
• The action of digestive liquids on food is enhanced by chewing in the mouth and churning in the stomach.
• At the end of digestion, key nutrients pass into the blood at the small intestine.
• The undigested food is eliminated as excrement.
• The digestive system uses mechanical digestion as demonstrated by Borelli and chemical action as discovered by Spallanzani.
• Chewing is a form of mechanical action.
• The body digests large particles of food into small nutrients, the components needed to survive.
• The body absorbs necessary nutrients and the rest is discarded.
• The large molecule is different for each living being.
• Humans cannot construct large molecules of other living beings and vice versa.

Blood Circulation

• The body receives oxygen through respiration.
• The body receives nutrients through digestion.
• Blood circulates through the entire body.
• Blood is a red liquid that circulates throughout the body.
• Blood transports oxygen and nutrients to the organs of the body.
• The heart circulates blood.
• Blood circulates throughout the body due to the heart pushing it through blood vessels.
• The heart functions like a pump. It contracts and relaxes.
• During relaxation, the heart fills with blood.
• During contraction, blood full of oxygen is then pushed towards other organs.
• Blood low in oxygen is pushed to the lungs to gain more oxygen.
• The heart is a pump containing two auricles and two ventricles, which facilitates circulation.
• The arteries transport blood.
• The auricles get filled with blood.
• Circulation is split into pulmonary and general.
• The pulmonary circulation is between the heart and lungs.
• General circulation is between the heart and other organs.
• Blood is a liquid that travels around the body inside blood vessels.
• Blood transports nutrients and respiratory gases
• Waste is manufactured by the organs
• The heart is a muscle that pushes blood into the blood vessels.
• The cardiovascular apparatus is a closed and linked system, transporting various substances through the blood.
• There are three kinds of blood vessels the arteries, veins, and capillary vessels.
• Lungs provide oxygen.

Exercise and Heart Rate

• During exercise, the cardiac rhythm accelerates and cardiac output increases.
• The heart pumps blood more rapidly to provide the muscles with oxygen and glucose for their function.
• More intense pumping also eliminates more carbon dioxide.
• During exercise, the body is working harder.
• During exercise, the heart pumping accelerates.
• Vessels are a path of travel throughout the organs.

Muscle Function

• When a muscle is in use, it contains less dioscygene, less glucose, and more carbon dioxide.
• Muscles use dioscygene and glucose to create carbon dioxide.
• The muscle used the dioscygene and discarded CO2.
• The body uses more dioxygene and glucose in activity, discarding more CO2.
• The muscle needs glucose in activity.
• Carbon dioxide is a residue from muscles.
• A resting muscle consumes less dioxygen than an active muscle.
• When exercising, the cardiac rhythm increases.
• If the body's core temperature is increased, the blood vessels may be damaged.
• The heart pumps oxygen rapidly.

Key Concepts

• Glucose: a sugar energy derived from plants.
• Cardiac rhythm: number of beats per minute, as expressed during a particular activity.
• Cardiac output: quantity of blood ejected by the heart in the span of one minute.