Digestive system (7) Flashcards
How is homeostasis involved in the digestive system?
> Digestive system is vital for homeostasis because it helps to ensure that cells are provided with nutritional requirements needed to maintain cellular functions
Balanced diet includes all of these: carbohydrates, lipids and proteins
DS reduces complexity of food molecules so we can absorb them into the bloodstream
Then transported to their site of action and used by cells to produce energy- this energy used for growth, repair, etc.
What is the role of the gastrointestinal tract?
> Digests and absorbs food
> Nutrients become more available in each step
What is the alimentary canal?
> Mouth > Pharynx > Oesophagus > Stomach > Small intestine > Large intestine
What are the accessory digestive organs?
> Teeth > Tongue > Gallbladder > Salivary glands > Liver > Pancreas
What are the 6 essential activities in the digestive process?
1) Ingestion (taking food into digestive tract)
2) Propulsion (swallowing and peristalsis- waves of contraction and relaxation of muscles in the organ walls)
3) Mechanical digestion (chewing)
4) Chemical digestion (catabolic breakdown of food e.g. by enzymes)
5) Absorption (movement of nutrients from GI tract to blood or lymph)
6) Defaecation (elimination of indigestible solid waste)
What is the peritoneum?
> The serous membrane of the abdominal cavity (largest in the body)
Has 2 parts which are in close contact- visceral and parietal
What is the visceral peritoneum?
> Covers the external surface of most digestive organs
What is the parietal peritoneum?
Lines the abdominal wall
What is the peritoneal cavity?
> Allows the digestive organs to glide across each other and along the body wall
Lubricates digestive organs
What is the oral/buccal cavity?
> The mouth
Bounded by lips, cheeks, palate and tongue
The oral orifice is its anterior opening
Continuous with the oropharynx posteriorly
How is the oral/buccal cavity made to withstand abrasions?
> Lined with thick stratified squamous epithelium which can withstand considerable friction
Gums, hard palate and dorsum of the tongue are slightly keratinised for extra protection against abrasion when eating
What is the tongue?
> Occupies the floor of the mouth
> Fills the oral cavity when mouth is closed
What are the functions of the tongue?
1) Gripping and repositioning food during chewing
2) Mixing food with saliva and forming the bolus (bolus is food mixed with saliva)
3) Begins process of deglutition (swallowing)
4) Initiation of speech
What are the salivary glands?
> Extrinsic glands are parotid, submandibular and sublingual
Intrinsic glands are scattered throughout the oral mucosa (the moist membrane covering in the mouth)
They produce and secrete saliva
What are the functions of saliva?
1) Cleanses the mouth
2) Moistens and dissolves food chemicals so they can be tasted
3) Aids in bolus formation
4) Contains amylase (an enzyme) which breaks down starch