Unit 1 - AOS2 - Digestive system Flashcards
3 points that make a mammal
- Give birth to live young
- Have the ability to produce milk to feed to young
- have hair or fur
Autotroph
Create their own energy through photosynthesis or chemosynthesis (plants at the bottom of the ocean)
Heterotroph
Cannot create their own energy,
- Therefore, get their energy through consuming other autotrophs or heterotrophs
Herbivore
Eat plants
- Therefore eat a lot of cellulose (carbohydrate that forms plant cell walls)
- e.g. horse
Carnivore
Eat meat
- gut produces enzymes to break down protein (protease)
- e.g. dog
Omnivore
Eat both plants and animals
- Share features from herbivores and carnivores
- e.g. humans
Carbohydrates
- Is broken down to glucose and stored as polysaccharide and glycogen in liver and muscles of animals
- Glucose breaks down to produce ATP during cellular respiration
Fats
- required for cell membrane, hormones and vitamin
- excess fat is stored under the skin tissue and surrounding organs
Protein
- Required for protein synthesis
- Stored as amino acids
essential amino acids
the 9 amino acids that humans cannot make
- Found in milk, effs and meat and cannot be stored.
Vitamins
- Organic (made from carbon and/or hydrogen and oxygen)
- required to make particular enzymes
Minerals
- inorganic
- Obtained through diet (calcium, potassium, iron, magnesium, sodium)
Chemical digestion
uses enzymes which break down complex compounds into simple compounds
the 3 main kinds of digestive enzymes
Amylase:
- Act on carbohydrates (e.g. starch -> glucose)
Protease:
- Act on proteins
Lipase:
- Act on lipids
4 main roles of the digestive system
- Ingestion - eating or drinking nutrients
- Digestion - food is broken up mechanically or chemically.
- Absorption - taking up digested molecules into the internal environment of the cells in the digestive tract.
- Egestion - the removal of wastes from the body
Chemical digestion
food is broken through the actions of enzymes and is converted into a substance suitable for absorption.
what are secretory epithelial cells & name them
- these cells are distributed through the digestive system depending on their function
- A combination of these cells makes up the tissues found within our digestive system
- Mucous cells
- G cells
- Parietal cells
- Chief cells
- Goblet cells
Mucous cells
secrete and alkaline mucus that protects the epithelium against shear stress and acid.
G cells
secrete gastrin which stimulates acid secretion
Parietal cells
secrete hydrochloric acid
Chief cells
secrete protease’s (enzymes that break down protein)
Goblet cells
secrete a mucous that protects the stomach lining from the acid
Name the layers of the tissues in the intestinal wall
-
Muscular layer - Outer layer (longitudinal layer)
- Inner layer (circular layer) - Submucosa
-
Mucosa - muscularis mucosa
- Lamina propria
- Epithelium - Villi (small intestine)
- Microvilli (small intestine)
Mucosa
Inner most layer of the muscle wall (intestinal wall)
- Epithelium
- Lamina propria (underlying loose connective tissue layer)
- Muscularis mucosa (thin layer of smooth muscle)
Submucosa
Is the thick layer of loose connective tissue that surrounds the mucosa
- Contains blood vessels, lymphatic vessels and nerves.
Muscularis externa
- smooth muscles responsible for movements of the digestive tract.
- Inner and outer layer
Villi
Tiny, finger-like projections that protrude from the epithelial lining of the intestinal wall.
- create a large SA:V ratio
- Contains Micro villi (tiny hair-like structures)
Function of the digestive system
responsible for the digestion of food and the absorption of nutrients.
Length of the digestive system
~30 feet (9m)
the 3 things the mouth contains that help with digestive
1. Salivary glands
- produces water, mucus, and amylase
- 3 major glands (sublingual, submandibular, parotid)
2. Teeth
- Form of mechanical digestion
- Food is broken down into smaller pieces and mixed with saliva
Incisors: used for cutting and cropping
Canines: Used to hold and tear food
Premolars and molars: used for grinding and chewing
3. Tongue
- Pushes the food to the teeth and to the back of the throat
Type of teeth Herbivores have
- Incisors to cur food (these are often only on the lower haw)
- Large ridged molars to grind food
Type of teeth carnivores have
- Small incisors
- Large and sharp canines to tear meat off bones
Type of teeth omnivores have
- Molars that roll and crush a variety of foods
Bolus
lump/ball of food
Esophagus
Muscular tube that connects the pharynx to the stomach
Peristalsis
Muscles contractions that occur in the esophagus, that moves the bolus into the stomach
Stomach
Organ that releases acids and enzymes to digest your food
- Completes both mechanical and chemical digestion
- muscles twist and churn to mix food with acids and enzymes (mechanical digestion)
- Hydrochloric acid (HCI) and pepsin break down the food
coats the lining of the stomach to prevent acids and enzymes from self-digestion
Mucus
Chyme
soupy fluid of partially digested food that exits the stomach into the small intestine
Small intestine
location where nutrients are absorbed into the blood stream
- Duodenum
- Jejunum
- Ileum
Duodenum
- Acid in chyme is neutralized by bicarbonate
- Gall bladder (mixes bile with the chyme to aid breakdown of fats) and pancreas (mixes various enzymes to breakdown lipids, proteins, carbs and nucleic acids.
Jejunum
Location here most nutrients are absorbed into the blood streams
- Villi and Microvilli
Ileum
Absorbs various vitamins and remaining nutrients from the chyme
Large intestine structure and function
Structure
1. Ascending colon
2. Transverse colon
3. Descending colon
4. Rectum
5. Anus
Function
- Extracts moisture from the chyme prior to removal from the body (diarrhea and constipation)
- Home to helpful bacteria
- Rectum: stores feces until elimination
- Anus: ring of muscles
Accessory organs definition
An organ that helps with digestion but is not part of the digestive tract
Pancreas
- Releases bicarbonate to neutralize the acid from the stomach
- Releases enzymes to further brake down peptides into amino acids and carbs into smaller sugars
Liver
- Processes the nutrients absorbed from the small intestine
- Also detoxifies potentially harmful chemicals
- Storage of excess carbs from glycogen
Gall bladder
- releases bile into small intestine
- Bile breaks down large fat droplets into smaller droplets (mechanical digestion –> emulsification)
- Along side this using chemical digestion enzymes break down fat droplets into glycerol and fatty acids
- Aids in neutralising stomach acids
