Digestive system Flashcards
Digestive system functions
- Ingestion and mastication(chewing)
- Propulsion and mixing
- Digestion and secretion
- absorption
- elimination
Digestive track
The path that food takes to be turned into energy or excreted
Associated organs
- salivary glands
- liver
- pancreas
Main organs
- oral cavity
- pharynx
- esophagus
- stomach
- small and large intestine
- Anus
Stratified epithelium
protective layer of the mouth
columnar epithelium
protects the digestive tract from digestive fluids
Tunic
layers of the digestive track
Mucosa
inner layer that is made of mucous epithelium, lamina propria, and the muscularis mucosae
Submuscosa
second layer of thick loose connective tissue that is activated by the plexus
plexus
intertwining blood vessels and nerves
muscularis
third layer that is made of circular smooth muscle and longitudinal smooth muscle and combine the a plexus to make the enteric nervous system.
enteric nervous system
a division of the autonomic nervous system that focuses on movement through the digestive track
serosa
outermost layer of the digestive track that is made of a smooth epithelial layer and connective tissue
adventitia
the outside covering of an organ
Peritoneum
a smooth covering of the serous membrane around the abdominal cavity and abdominal organs
Visceral peritoneum
covering that covers the organs
parietal peritoneum
covers the walls of the abdominal cavity
Peritonitis
inflammation of the peritoneal membranes that results from chemical irritation
mesenteries
connective tissue that holds the organs in place and provides a route for blood vessels and nerves
Omental bursa
pocketlike sac inside the greater omentum
greater omentum
double fold of mesentery that extends from the stomach
retroperitoneal
the organs without mesenteries that are along the abdominal wall like descending colon, rectum, kidneys, adrenal gland and urinary bladder
Lips
formed by the orbicularis oris muscle that helps orient food for chewing
Cheeks
the lateral walls of the oral cavity made by the buccinator muscles that help keep food in place for chewing
mastication
scientific term for mechanical digestion or chewing
Tongue
A muscle that moves the food around and has taste receptors. It is held in place by the frenulum
Teeth
breaks down food and is divided into central, incisors, canine, two molars and wisdom teeth
Tooth regions
- Crown - part of tooth covered by enamel
- neck - connects tooth to gums
- Root - contains nerves
Pulp
a material of connective tissues, blood vessles, and nerves that fill the pulp cavity in the center of the tooth
Gingiva
dense tissue covered by muscular membrane (gums)
Periodontal ligaments
secure the teeth
Palate
Roof of the oral cavity that separates it from the nasal cavity
Hard and soft palate
Hard - anterior part that contains bones
soft- posterior part that only has muscle
Uvula
extension of the soft palate
Tonsils
lymphoid tissue in the lateral posterior walls of the oral cavity
salivary glands
three glands that produce saliva to breakdown macromolecules
parotid glands
located under each ear and their saliva ducts enter the oral cavity next to the second molars
submandibular glands
producing mucous secretions and is found along the inferior border of the mandible
sublingual glands
smallest salivatory gland that is found beneath the mucous membrane on the floor of the oral cavity
Saliva purpose
keep the oral cavity moist, prevent bacterial infections, neutralize pH, prevent ulceration and infection (cavities), begins the process of digestion
Saliva enzymes
salivary amylase - breaks down starch
Lysozyme - antibacterial
mucus - lubricates food
serous saliva - moistens food and neutralizes pH
Pharynx
connects the mouth and esophagus
Esophagus
muscular tube that carries food to the stomach
Process of swallowing
- Voluntary phase - bolus from the mouth leaves by being pushed by the tongue against the hard palate
- Pharyhgeal phase - reflexes react to close off the nasopharynx by raising the oropharynx and muscles contract to force the bolus down the pharynx
- The epiglottis closes the opening to the larynx
- the esophagus muscles contract in peristaltic waves to push food into stomach
Parts of stomach
Cardiac part - at the gastro-esophageal opening
fundus - superior to the opening
body - the main part that causes a turn
pyloric - opens into the pyloric sphincter into the small intestine
Three layers of the stomach purpose
churn the food to mechanically digest it
Gastric pits
openings for gastric glands
types of gastric glands
surface mucous cells - inner surface and produce mucus to protect the stomach lining
mucous neck cells - produce mucus
parietal cells - produce hydrochloric acid
endocrine cells -produce regulatory hormones
Chief cells - produce pepsinogen
Pepsin
a digestive enzyme produced by the stomach and digests protiens
Chyme
food and stomach secretions
Intrinsic factor
binds to vitamin B 12 and makes it easier to be absorbed
What controls stomach secretions
CNS
Cephalic phase
- Taste, smell, or though of food triggers CNS
- Vagus nerves carry action potential to stomach
- Gastrin and histamine are secreted into blood
- Hormones trigger secretions
(start)
Gastric phase
1 Distention of stomach
2. secretions stimulated
3. local reflexes,
4. secretions stimulated
(go for it)
Intestinal phase
- Chyme with <2 pH enters stomach
2.chemoreceptors are stimulated - CNS causes reflexes
- secretions inhibited
(slow down)
Duodenum
the first division of the small intestine that connects to the stomach, the common bile duct and the pancreatic duct
jejunum
second part of the small intestine that is the longest part
ileum
connects to the large intestine
Villi
projections from the mucous membrane in the small intstine that increases surface area for digestion
lacteal
blood capillary network in villi that absorbs the nutrients
types of cells in small intestine
absorptive cells, goblet cells (produce mucus), granular cells, endocrine cells
Small intestine enzymes
Peptidases - digest protiens
Disaccharidases - digest sugars
Hepatic portal vein
carries nutrient-rich blood from the digestive tract to the liver
Haptic veins
Where blood exits the liver into the inferior vena cava
Hepatic lobules
hexagon-shaped regions surrounded by connective tissue that make up the regions of the liver
bile
fluid secreted from the liver that is stored in the gallbladder and contains salts, pigments, cholesterol, lipid-soluble hormones, lecithin, bicarbonate ions, and fats.
Bile movement
- Exists the liver via the common hepatic duct
- The gallbladder on the inferior surface of the liver connects to the cystic duct to take and joins the common hepatic duct to form the common bile duct
- Joins pancreatic duct
- Open into the duodenal papilla what is regulated by a sphincter
- Pancreatic secretions may also enter
Functions of the liver
Digestion, excretion, nutrient storage, nutrient conversion, detoxification, synthesis of new molecules
Bile function
neutralize stomach acid and emulsify lipids. Since the pancreas cannot tolerate the pH of stomach acid
Bile salts
emulsify lipids so lipase can function
Liver storage
Store lipids, vitamins, copper, iron, sugar as glycogen, and use amino acids to make ATP, by-products of metabolism
Liver transformation
Transform fats into phospholipids with extra choline and phosphorus. Convert ammonia to urea
pancreas
extending from the duodenum to the spleen and secreting digestive enzymes to the duodenum and insulin and glucagon
Pancreatic islet
small glands on the pancreas that produce insulin and glucagon
Acini
produce digestive enzymes in the pancreas and empty them via the pancreatic duct
Pancreatic secretions
bicarbonate ions, trypsin(proteins), chymotrypsin (lipids), carboxypeptidase (carbs), nucleases (nucleic acids)
Cecum
Sac that forms the beginning of the large intestine and connects to the appendix
Colon
The long tube of the large intestine forms the feces by absorbing water and salts
Rectum
muscular tube that holds the feces
