The Digestive System Flashcards
The human digestive system consists of
The alimentary canal and accessory organs
The alimentary canal
Long, tubular structure that extends throughout the body
The alimentary canal consists of
Mouth and mouth cavity
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine and anus
The accessory organs include the following
Tongue
Salivary glands
Pancreas
Liver
Fall bladder
Five main processes in nutrition
Ingestion, digestion, absorption, assimilation and egestion
Ingestion
The food is taken in and enters the alimentary canal
Digestion
Food is exposed to mechanical and chemical processes that change solid, insoluble food to simpler, soluble substances.
Absorption
The end products of digestion are absorbed into the blood stream
Assimilation
The cells absorb the nutrients from the blood and use It to build new cell structures and compounds
Egestion
The process through which undigested remains are removed from the body in the form of faeces.
Necessity of food
It provides energy through the egestion of carbohydrates and fats.
It provides growth and repair of damaged tissues through the egestion of proteins.
It regulates body processes such as cellular respiration and excretion which requires ingestion of vitamins vitamins, water and mineral salts
Herbivores-animals that feed on plant material
Consume large amounts of cellulose (found in cell walls). Some herbivores have microorganisms in their small intestine that digest cellulose which is hard to digest. Large amount of plant material is consumed as it has a very low energy value with the incisors of herbivores and large premolar and molars to grind the food.
Herbivores produce large amounts of faeces
Because they eat so much indigestible plant material
Herbivores have very long, specialized alimentary canals while carnivores
Have a shorter alimentary canal because the protein is easier to digest along with the stomach which has acidic medium that easily digests protein.
Carnivores have sharp pointed incisors to
Bite food, long string canines to pierce the prey and to kill and tear it apart.
Carnivores eat less than herbivores
Because fats and proteins have a much higher energy value than plant material therefore less faeces are produced.
Mouth and mouth cavity
The mouth is the upper opening of the alimentary canal.
The opening of the mouth is surrounded by 2 fleshy lips.
The cavity on the inside is known as the mouth cavity which is lined with a mucous membrane.
The roof of the mouth cavity consists of a hard, ridged palate at the front and a soft palate at the back which ends in the uvula, which closes the opening to the nasal cavity when swallowing.
The mouth cavity also contain the tongue and the teeth toward the front as well as the openings of the 3 pairs of Salivary glands (tongue, teeth and Salivary glands)
Functions of the mouth and mouth cavity
The mouth cavity receives the food and begins the process of mechanical digestion by breaking down larger particles of food into smaller particles and mixing it with saliva
Pharynx
The back of the moth cavity opens to the Pharynx which leads to 2 openings : the Oesophagus and trachea(windpipe)
During swallowing, the opening of the trachea
Is closed by a leaf-shaped cartilage structure called the epiglottis which prevents food from entering the trachea and choking a person.
Function of the Pharynx
The Pharynx is the common passage for food and air from the mouth to the Oesophagus and the trachea.
Passageway that connects nasal and oral cavity to Oesophagus.
Respiratory and digestive function occur and food triggers involuntary reflexes
Oesophagus
A hollow, muscular tube that connects the Pharynx to the stomach which is located behind the trachea.
Function of the Oesophagus
The muscles in the wall of the Oesophagus are responsible for peristaltic movements which push the food bolus forward.
Food bolus
A round ball of chewed food that is mixed with saliva in the mouth cavity and pushed in the direction of the Oesophagus during swallowing