Chapter 24 Flashcards
The Digestive system
anabolism - uses raw materials to synthesize essential compounds
catabolism - decomposes substances to provide energy cells need to function
Digestive tract
protein -> amino acids
fats -> fatty acids
carbs -> glucose
What is the digestive tract?
is also called the gastrointestinal (GI) tract or alimentary canal
is a muscular tube (smooth muscle)
Extends from oval cavity to anus - passes through pharynx(digestive & respiratory) esophagus, stomach, and small/large intestines
When does absorption happen?
it happens AFTEAR digestion
what’s digestion?
what 2 ways?
big stuff turning into small (breakdown)
2 ways
- mechanically (teeth)
- chemical(acid and enzymes)
What are the 6 functions of the digestive system?
- Ingestion
- Mechanical processing
- Digestion
- Secretion
- Absorption
- Excretion
When does ingestion occur?
Occurs when materials enter digestive tract via the mouth
what is mechanical processing?
Crushing and shearing
Makes material easier to propel along digestive tractg
What happens in Digestion?
the chemical breakdown of food into small organic fragments for absorption by digestive epithelium
What is secretion?
is the release of water, acids, enzymes, buffers, and salts
by epithelium of digestive tract
by glandular organs
What is absorption?
movement of organic substrates, electrolytes, vitamins, and water
- across the digestive epithelium
- into the interstitial fluid of the digestive tract
What is excretion?
Removal of waste products from body fluids
- Process called defecation removes feces
Histological Organization of the Digestive Tract
what are the four major layers of the digestive tract?
- Mucosa
- Submucosa
- Muscular externa
- Serosa (most superficial)
Histological Organization of the Digestive Tract
Characteristics of the movement of digestive tract
The movement of digestive materials
- by muscular layers of digestive tract
– Consist of visceral smooth muscle tissue
– Has rhythmic cycles of activity
– Controlled by pacesetter cells
Peristalsis, what is it?
- Consists of waves of muscular contractions
- moves a bolus along the length of the digestive tract
What are the functions of the oral cavity?
- Sensory analysis
- of material before swallowing - Mechanical processing
- through actions of teeth, tongue, and palatal surfaces - Lubrication
- Mixing with mucus and salivary gland secretions - Limited digestion
- of carbohydrates and lipids
Salivary Glands, 3 pairs secrete into oral cavity?
- Parotid salivary glands
- Sublingual salivary glands
- Submandibular salivary glands
What are the functions of saliva?
-lubricate mouth
- Moistening and lubricating materials in the mouth
- Dissolving chemicals that stimulate taste buds and provide sensory information
- Initiating digestion of complex carbohydrate by the enzyme salivary amylase (ptyalin or alpha-amylase) (break down big carbohydrates)
Saliva
Glands produce 1.0-1.5 liters of saliva each day
- 70% by submandibular glands
- 25% by parotids
- 5% by sublingual glands
99.4% water
0.6% includes
The Teeth
- Tongue movements pass food across occlusal surfaces of teeth
- Chew (masticate) food
Deciduous Teeth
also called primary teeth, milk teeth, or baby teeth
- 20 temporary teeth of primary dentition
- Five on each side of upper and lower jaws
– 2 incisors
– 1 cuspid
– 2 deciduous molars
Secondary Dentition
Also called permanent dentition
- replaces deciduous teeth
32 permanent teeth
8 on each side.
2 incisors
1 cuspid
5 molars
The pharynx ( throat)
- A common passageway for solid food, liquids, and air
- Regions of pharynx:
- Nasopharynx
- Oropharynx
- Laryngopharynx
Food passes through the oropharynx and laryngopharynx to the esophagus
