DIGESTIVE SYSTEM Flashcards
Breakdown of ingested food; absorption of nutrients into the blood
Digestion
Production of cellular energy (ATP); Constructive and degradative cellular activities
Metabolism
Two main groups of organs of the digestive system:
Alimentary canal
Accessory digestive organs
Continuous coiled hollow tube
Alimentary canal
Organs of the alimentary canal:
Mouth, Pharynx, Esophagus, Stomach, Small intestine, Large intestine, Anus
Part of the mouth which protects the anterior opening
Lips (libia)
Parts of the mouth:
Lips, Cheeks, Hard palate, Soft palate, Uvula, Vestibule, Oral cavity, Tongue, Tonsils
Form the lateral walls
Cheeks
Form the anterior roof
Hard palate
Forms the posterior roof
Soft palate
Fleshy projection of the soft palate
Uvula
Space between lips externally and teeth and gums internally
Vestibule
Area contained by the teeth
Oral cavity
Attached at hyoid and styloid processes of the skull, and by the lingual frenulum
Tongue
Processes of the mouth:
- Mastication (chewing) of food
- Mixing masticated food with saliva
- Initiation of swallowing by the tongue
- Allowing for the sense of taste
Pharynx anatomy:
- Nasopharynx
- Oropharynx
- Laryngopharynx
It is not part of the digestive system
Nasopharynx
Posterior to oral cavity
Oropharynx
Below the oropharynx and connected to esophagus
Laryngopharynx
Serves as a passageway for air and food
Pharynx
Food is propelled to the esophagus by two muscle layers:
- Longitudinal inner layer
- Circular outer layer
Food movement is by alternating contractions of the muscle layers
Peristalsis
Runs from pharynx to stomach through diaphragm; Conducts food by peristalsis; Passageway for food only
Esophagus
Innermost layer; Moist membrane; Surface epithelium; Small amount of connective tissue; Small smooth muscle layer
Mucosa
Just beneath the mucosa; Sofr connective tissue with blood vessels, nerve endings, and lymphatics
Submucosa
Smooth muscle; Inner circular layer; Outer longitudinal layer
Muscularis externa
Layers pf serous fluid-producing cell
Serosa
Visceral peritoneum
Serosa
Three separate networks of nerve fibres
- Submucosal nerve plexus
- Myenteric nerve plexus
- Subserous plexus
Located on the left side of the abdominal cavity
Stomach
Where does the food enter to the stomach?
Cardioesophageal sphincter
Regions of the stomach
Cardiac region, Fundus, Body, Phylorus
Food in the stomach empties into the small intestine at the _____________
Pyloric sphincter
Internal folds of the mucosa in the stomach
Rugae
External regions of the stomach
Lesser curvature, Greater curvature
Layers of the peritoneum attached to the stomach
Lesser omentum
Greater omentum
Attaches the liver to the lesser curvature
Lesser omentum
Attaches the greater curvature to the posterior body wall
Greater omentum
Acts as storage tank for food; Site of food breakdown; Chemical breakdown of protein begins; Delivers chyme to the small intestine
Stomach
Processed food
Chyme
Specialized mucosa of the stomach
Mucous neck cells, Gastric glands, Chief cells, Parietal cells, Endocrine cells
Produce a sticky alkaline mucus
Mucous neck cells
Secrete gastric juice
Gastric glands
Produce protein-digesting enzymes
Chief cells
Protein-digesting enzymes
Pepsinogens
Produce hydrochloric acid
Parietal cells
Produce gastrin
Endocrine cells
The body’s major digestive organ
Small intestine
Site of nutrient absorption into the blood; Muscular tube extending form the pyloric sphincter to the ileocecal valve
Small intestine
Subdivisions of the small intestine:
Duodenum, Jejunum, Ileum
Attached to the stomach; Curves around the head of the pancreas
Duodenum
Attaches anteriorly to the duodenum
Jejunum
Extends from jejunum to large intestine
Ileum
Fingerlike structures formed by the mucosa; Give the small intestine more surface area
Villi of the Small intestine
Small projections of the plasma membrane; found on absorptive cells
Microvilli of the Small intestine
Structures involved in absorption of nutrients
Absorptive cells
Blood capillaries
Lacteals
Called circular folds or _______ __________
Plicae circulares
Larger in diameter, but shorter than the small intestine; frames the internal abdomen
Large intestine
Absorption of water; eliminates indigestible food form the body as feces
Large intestine
Does the large intestine participate in digestion of food?
No
What produces mucus to act as lubricant in the large intestine?
Goblet cells
Structures of the large intestine:
Cecum
Appendix
Colon
Rectum
Anus
Saclike first part of the intestine
Cecum
Accumulation of lymphatic tissue that sometimes becomes inflamed (appendicitis); hangs from the cecum
Appendix
S-shaped sigmoidal, ascending, transverse, descending
Colon
External body opening
Anus
Accessory digestive organs
Salivary glands
Teeth
Pancreas
Liver
Gall bladder
Saliva-producing glands
Salivary glands
Mixture of mucus and serous fluids; helps to form a food bolus
Saliva
Saliva contains ______________ to begin starch digestion
Salivary amylase
The role is to masticate (chew) food
Teeth
Produces a wide spectrum of digestive enzymes that brealdown all categories of food
Pancreas
Endocrine products of pancreas
Insulin, Glucagon
Largest gland in the body; located on the right side of the body under the diaphragm
Liver
Liver is connected to the gall bladder via the common __________ _____
Hepatic duct
Produced by cells on the liver
Bile
Composition of bile
Bile salts, Bile pigment, Cholesterol, Phospholipids, Electrolytes
Sac found in the hollow fossa of liver; Stores bile from the liver by way of the cystic duct
Gall bladder
Processes of the digestive system
Ingestion
Propulsion
Peristalsis
Segmentation
Mechanical digestion
Chemical digestion
Absorption
Defacation
Getting food into the mouth
Ingestion
Moving foods from one region of the digestive system to another
Propulsion
Alternating waves of contraction
Peristalsis
Moving materials back and forth to aid in mixing
Segmentation
Mixing of food in the mouth by the tongue; churning of food in the stomach
Mechanical digestion
Enzymes break down food molecules into their building blocks
Chemical digestion
End products of digestion are absorbed in the blood or lymph
Absorption
Food must enter _____________ and then into blood or lymph capillaries to be absorbed
Mucosal cells
Elimination of indigestible substances as feces
Defecation
Digestive activities are controlled by reflexes via the ________________
parasympathetic division
Digestive activities of the mouth
Mechanical breakdown, Chemical digestions
Breaking of starch into maltose by __________________
Salivary amylase
Also known as swallowing
Deglutition
Two phases of deglutition
Buccal phase
Pharyngeal-esophageal phase
Occurs in the mouth; food is formed into bolus; and the bolus is forced into the pharynx by the tongue and is voluntary
Buccal phase
Involuntary transport of the bolus
Pharyngeal-esophageal phase
__________, __________, _________ block mouth, nasopharynx, and larynx respectively.
Tongue, soft palate, epiglottis
What moves the bolus toward the stomach?
Peristalsis
When the food is pressed against the cardioesophageal sphincter, what happens to it?
It is opened
Presence of food or falling pH causes the release of
Gastrin
It causes the stomach to release protein-digesting enzymes
Gastrin
This makes the stomach contents very acidic
Hydrochloric acid
Why should stomach be extremely acidic?
To activate pepsinogen to pepsin for protein digestion
Inhibits growth of microorganisms
An active protein digesting enzyme
Pepsin
Works on digesting milk protein
Rennin
The only absorption that occurs in the stomach is of _________ and ___________
Alcohol, aspirin
The pylorus meters out chyme into the small intestine, which is ________ at a time
30 mL
The stomach empties in _________ to ________ hours
four, six
Carry out about half of all protein digestion
Trypsin
Responsible for fat digestion
Lipase
Digest nucleic acid
Nucleases
What nuetralizes acidic chyme?
Alkaline content
This nerve causes the release of pancreatic juice
Vagus nerve
Chyme entering duodenum causes the duodenal mucosal cells to release __________ and _____________
Secretin, Cholecystokinin
Upon reaching the pancreas, ___________________ induces secretion of enzyme-rich pancreatic juice; secretin causes secretion of _____________________________
Bicarbonate-rich pancreatic juice
Most substances are absorbed by _____________ through cell membrane
Active transport
Lipids are absorbed by _____________
Diffusion
The major means of moving food
Peristalsis
Mix chyme with digestive juices; aid in propelling food
Segmental movements
Are there digestive enzymes produced in large intestine?
None
In large intestine, what digests remaining nutrients?
Resident bacteria
Water and Vitamins K and B are absorbed
Large intestine
Slow, powerful movements; occur three to four times per day
Mass movements
Presence of feces in the rectum causes a ________________
Defecation reflex
Defecation occurs with relaxation of the _______________________________
Voluntary (external) anal sphincter
Mechanisms that may regulate food intake
Levels of nutrients in the blood
Hormones
Body temperature
Psychological factores
Amount of heat produced by the body per unit of time at rest
Basic metabolic rate (BMR)
Factors that influence BMR
Surface area
Gender
Age
Amount of thyroxine
Does having small body means having higher BMR?
Yes
Is it male or female that has the higher BMR?
Male
Children and adolescents have a (higher or lower) BMR
higher
More thyroxine means (higher or lower) metabolic rate
higher
Total amount of kilocalories the body must consume to fuel ongoing activities
Total metabolic rate (TMR)
The alimentary canal is continuous tube by the _____________ of development
fifth
The developing fetus receives all nutrients through the _______________
Placenta
Teething begins around age _______________
Six months
Middle age digestive problems
Ulcers, Gall bladder problems
Activity of digestive tract in old age:
Fewer digestive juices
Peristalsis slows
Diverticulosis and cancer are more common
