Digestive Flashcards
What is the primary function of the digestive system?
To transform food into nutrients needed for metabolic processes.
What are the two main groups of the digestive system?
- Alimentary Canal
- Accessory Digestive Organs
Define ingestion in the context of the digestive system.
The process of taking in food through the mouth.
What are the three characteristics of propulsion in the digestive system?
- Swallowing
- Peristalsis
- Mass movements
What is the process of mixing in the digestive system?
Occurs in the stomach as a result of smooth muscle contraction.
What is mastication?
Mechanically and chemically breaks down food, increasing surface area for enzymes.
What substances does the digestive system secrete to aid in digestion?
- Mucus
- Hydrochloric acid
- Enzymes
- Bile
- Pancreatic juice
What is digestion?
The process that converts nutrients in ingested food into forms that can be absorbed.
What is absorption in the digestive system?
The process of taking digested nutrients into the bloodstream.
What are villi?
Tiny finger-like structures in the small intestine that increase surface area for absorption.
What is egestion?
The process of eliminating waste material from the digestive tract.
Name the five layers of the pharynx.
- Mucous membrane
- Submucosa
- Pharyngobasilar fascia
- Muscular layer
- Buccopharyngeal fascia
What is the role of the mucous membrane in the pharynx?
It protects the pharynx from abrasion and helps filter and clean air.
What is the function of the submucosa in the pharynx?
Provides support and contains glands that secrete mucus.
What is peristalsis?
The involuntary process of swallowing that propels food through the digestive tract.
Fill in the blank: The _______ is responsible for the segmental contractions and peristaltic movements in the gastrointestinal tract.
[muscularis externa]
What is the function of the muscularis externa in the esophagus?
Helps propel food to the stomach through peristalsis.
What is the significance of the pyloric sphincter?
It regulates the passage of chyme from the stomach to the duodenum.
What are the four regions of the stomach?
- Cardiac part
- Fundus
- Body
- Pyloric part
What is the primary function of gastric pits?
Act as entrances to gastric glands that produce gastric juice.
What do chief cells in the stomach produce?
Pepsinogen.
True or False: The mucosa of the small intestine is specialized for nutrient absorption.
True
What is the role of the serosa/adventitia in the digestive system?
It is the outermost layer that reduces friction with surrounding organs.
What are the three phases of swallowing?
- Voluntary phase
- Pharyngeal phase
- Esophageal phase
What is the function of the submucosa in the stomach?
Contains blood vessels and nerve plexuses that aid in controlling secretions and motility.
Fill in the blank: The _______ is responsible for the transport of food from the mouth to the stomach.
[esophagus]
What is the primary function of the large intestine?
Primarily responsible for mass movements that propel fecal matter toward the rectum.
What is the role of the buccinator muscle?
Compresses the cheek inward against the molars during mastication.
What do mucous neck cells produce?
Mucus
What is produced by parietal cells?
Hydrochloric acid and intrinsic factor
What type of chemicals do endocrine cells produce?
Regulatory chemicals
What do chief cells produce?
Pepsinogen
What is the function of propulsion and mixing in the stomach?
Mixing waves churn ingested materials and stomach secretions into chyme
How does the stomach secrete hydrochloric acid?
It creates an acidic stomach environment and activates pepsinogen
What occurs during mechanical digestion in the stomach?
Food is churned by mixing waves
What is absorbed in the stomach?
Only a few substances
What is the primary site for nutrient absorption?
Small intestine
How long is the small intestine?
6 meters
What are the three subdivisions of the small intestine?
- Duodenum
- Jejunum
- Ileum
What is the length of the duodenum?
About 25 cm (12 in)
What role does the duodenum play in digestion?
Helps to further digest food coming from the stomach
What digestive juices empty into the duodenum?
- Juices from the liver
- Gallbladder
- Pancreas
What is the jejunum primarily responsible for?
Absorption of important nutrients like sugars, fatty acids, and amino acids
What connects the ileum to the large intestine?
Cecum
What are the three modifications of the small intestine that increase surface area?
- Circular folds (plicae circulares)
- Villi
- Microvilli
What is the function of absorptive cells in the small intestine?
Produce digestive enzymes and absorb digested food
What do goblet cells produce?
Protective mucus
What is the role of granular cells in the intestine?
Protect the intestinal epithelium from bacteria
What is the function of endocrine cells in the small intestine?
Produce regulatory hormones
What are intestinal glands also known as?
Crypts of Lieberkuhn
What is the primary function of the large intestine?
Dry out indigestible food residue by absorbing water
How long is the large intestine?
About 2.5 meters
What are the four subdivisions of the large intestine?
- Cecum
- Colon
- Rectum
- Anal canal
What is the length of the colon?
1.5 - 1.8 meters
What is appendicitis?
Inflammation in the appendix
What are haustra?
Small, pocketlike sacs in the large intestine
What is the function of the rectum?
Holds feces until eliminated
What are the two types of anal sphincters?
- Internal anal sphincter
- External anal sphincter
What do accessory organs of the digestive system do?
Contribute to breakdown and absorption of food
What is the role of teeth in digestion?
Mechanical breakdown of food
What are the two sets of teeth humans develop?
- Deciduous teeth
- Permanent teeth
What are the four types of teeth based on shape and function?
- Incisors
- Canines
- Premolars
- Molars
What are the three main regions of a tooth?
- Crown
- Neck
- Root
What is the function of dental pulp?
Contains blood vessels, nerves, and connective tissue
What supports teeth in the jawbone?
- Periodontal ligament
- Alveolar bone
- Gingiva
What are the two parts of the palate?
- Hard palate
- Soft palate
What are the three types of tonsils?
- Palatine tonsils
- Lingual tonsils
- Pharyngeal tonsils
What role does the tongue play in digestion?
- Mechanical digestion
- Taste perception
- Swallowing
What do salivary glands secrete?
Saliva
What are the three major salivary glands?
- Parotid glands
- Submandibular glands
- Sublingual glands
What is the function of bile?
Emulsifies fats
What is bilirubin?
A yellow pigment produced when red blood cells are broken down
What are gallstones primarily composed of?
- Cholesterol
- Bilirubin
What is the role of the gallbladder?
Stores and concentrates bile
What is the pancreas responsible for secreting?
Digestive enzymes
What are the two main functions of the pancreas?
- Digestive function
- Endocrine function
What are the four main parts of the pancreas?
- Head
- Neck
- Body
- Tail
What is the function of insulin?
Lowers blood sugar levels
What is the role of glucagon?
Raises blood sugar levels
What is the primary function of somatostatin?
Inhibits the release of insulin and glucagon
What is the function of somatostatin in the pancreas?
Inhibits the release of both insulin and glucagon
Secreted by delta cells within the islets of the pancreas.
What regulates digestive processes and may play a role in appetite regulation in the pancreas?
Pancreatic polypeptide
Secreted by PP cells within the islets.
What is the main pancreatic duct’s role?
Collects digestive enzymes from acini and merges with the common bile duct
It forms the hepatopancreatic ampulla, opening into the duodenum.
What is chyme?
A thick, semi-liquid mixture formed when food combines with stomach secretions
Some digestion occurs in the stomach, but this is not its main role.
Name the four key substances produced by gastric glands in the stomach.
- Hydrochloric acid
- Pepsin
- Mucus
- Intrinsic factor
What is the pH level of hydrochloric acid in the stomach?
About 2.0
This acid kills microorganisms and activates pepsin.
What is the function of pepsin?
Breaks covalent bonds of proteins to form smaller peptide chains
Exhibits optimum activity at a pH of about 2.0.
What does intrinsic factor bind with to enhance absorption?
Vitamin B12
Important for DNA synthesis and red blood cell production.
What are the three phases of gastric secretion regulation?
- Cephalic phase
- Gastric phase
- Intestinal phase
What triggers the cephalic phase of gastric secretion?
The CNS in response to the anticipation of food
Begins even before food enters the stomach.
What hormone is released during the gastric phase to stimulate secretory activity?
Gastrin
It is carried back to the stomach via the bloodstream.
True or False: The intestinal phase of gastric secretion inhibits gastric secretions.
True
What are the two types of stomach movements that assist in digestion?
- Mixing waves
- Peristaltic waves
What do mixing waves do in the stomach?
Thoroughly mix ingested food with stomach secretions
The more fluid part is pushed toward the pyloric sphincter.
What triggers hunger pangs?
Low blood glucose levels
These pangs can occur 12 to 24 hours after the last meal.
What do intestinal secretions primarily contain?
Mucus, ions, and water
They lubricate and protect the intestinal wall.
What are the two major enzyme groups found in the small intestine?
- Peptidases
- Disaccharidases
What is the primary mechanical event that occurs in the small intestine?
Mixing and propulsion of chyme
What is the main secretion produced by the large intestine?
Mucus
Aids in lubricating intestinal contents and facilitating transport.
What are haustral contractions?
Slow, segmental movements occurring approximately every 30 minutes in the large intestine
They help mix and move contents slowly.
What is the gastrocolic reflex?
A response that stimulates rhythmic contractions in the large intestine soon after eating
It propels material toward the anus.
Define metabolism.
All of the reactions that take place within each cell of the body and provide energy.
What are the two metabolic pathways?
- Catabolism
- Anabolism
What is glycogenesis?
The process of storing excess glucose when blood glucose levels are high.
What occurs during gluconeogenesis?
Creation of glucose from non-carbohydrate sources
Such as fats, proteins, or their breakdown products.
What is the basal metabolic rate?
The rate at which your body expends energy while at rest.
What role do lymphatic vessels play in the body?
Transport lymph throughout the body and back to the bloodstream.
What is lymph?
A specific type of fluid collected by the lymphatic system from interstitial fluid.
What is the function of lacteals?
Specialized lymphatic vessels that absorb dietary fats in the small intestine.
What is chyle?
The milky lymph passing through lacteals due to high lipid content.
What are the main functions of the lymphatic system?
- Fluid balance
- Lipid absorption
- Defense
What is the role of lymph nodes?
Act as filters for lymph, trapping foreign invaders and presenting them to lymphocytes.
What are the two types of lymphatic vessels?
- Afferent vessels
- Efferent vessels
Where does the thoracic duct empty lymph into the bloodstream?
At the junction of the left subclavian and internal jugular veins near the left side of the neck.
What is the largest lymphatic vessel called?
Thoracic Duct
It collects lymph from the lower body, left arm, left side of the chest, and left side of the neck and head.
What lymphatic duct drains lymph from the right arm and right side of the chest?
Right Lymphatic Duct
It empties into the bloodstream at the junction of the right subclavian and internal jugular veins.
List the three factors that cause compression of lymphatic vessels.
- Contraction of surrounding skeletal muscle during activity
- Periodic contraction of smooth muscle in the lymphatic vessel wall
- Pressure changes in the thorax during breathing
What are lymphatic capillaries?
Tiny, closed-ended vessels consisting of simple squamous epithelium
They are more permeable than blood capillaries because they lack a basement membrane.
What is the primary function of lymph nodes?
To filter lymph and provide a site for immune cells to mount responses
They remove pathogens, foreign particles, and debris.
Approximately how many lymph nodes are there in the human body?
800
Concentrated in the neck, groin, armpits, chest, and abdomen.
What are the primary lymphatic organs?
- Bone Marrow
- Thymus
What is the primary site of lymphocyte production?
Bone Marrow
It generates both B-lymphocytes and T-lymphocytes.
What is the role of the thymus?
Maturation and selection of T-lymphocytes
It conducts positive and negative selection of thymocytes.
What occurs in the cortex of the thymus?
Initial stages of T cell maturation and positive selection
Thymocytes are tested for their ability to recognize self-MHC molecules.
What happens in the medulla of the thymus?
Negative selection of T-lymphocytes
T cells that bind strongly to self-antigens are eliminated.
What are secondary lymphatic organs?
Sites where lymphocytes encounter antigens and become activated
They house mature lymphocytes but do not produce them.
What is the function of the spleen?
Filters blood, removes old red blood cells, and stores lymphocytes
It plays a role in immune responses by activating lymphocytes.
What are the components of the internal structure of the spleen?
- Capsule
- Trabeculae
- White Pulp
- Red Pulp
What is splenectomy?
Surgical removal of the spleen
Performed for various reasons including trauma, blood disorders, cancer, and infection.
What are the three main types of tonsils?
- Palatine Tonsils
- Pharyngeal Tonsil (Adenoid)
- Lingual Tonsil
What is the primary role of mucosa-associated lymphoid tissue (MALT)?
Acts as a first line of defense against pathogens
Found in the linings of the digestive, respiratory, and genitourinary tracts.
What is immunity?
The ability to resist damage from pathogens, harmful chemicals, and internal threats.
What are the two types of immune systems?
- Innate (Non-specific Defense System)
- Adaptive (Specific Defense System)
What are the most important innate defenses?
- Physical Barriers
- Chemical Mediators
What are some examples of physical barriers in the innate immune system?
- Skin
- Mucous membranes
What is chemotaxis?
The movement of an organism or cell in response to a chemical stimulus.
What are the most important phagocytic cells?
- Neutrophils
- Macrophages
What is the function of neutrophils?
First white blood cells to enter infected tissues and increase the inflammatory response.
What are basophils and mast cells?
Motile and non-motile white blood cells involved in inflammation.
True or False: The spleen is involved in both blood filtration and immune responses.
True
What is agocytic activity in the late stages of an infection?
Cleaning up dead neutrophils and other cellular debris
Agocytic activity is crucial for resolving inflammation and restoring tissue homeostasis.
What are basophils?
Motile white blood cells derived from red bone marrow that can leave the blood to enter infected tissues
Basophils play a role in inflammatory responses and allergic reactions.
What are mast cells?
Nonmotile cells derived from red bone marrow located in connective tissue, especially near capillaries
Mast cells are key players in allergic responses and inflammation.
What are eosinophils?
A type of white blood cell that protects the body from parasites, allergens, and foreign bacteria; makes up less than 5% of white blood cells
Eosinophils are larger than most white blood cells.
What are natural killer (NK) cells?
A type of lymphocyte produced in red bone marrow that accounts for up to 15% of lymphocytes
NK cells destroy tumor cells or virus-infected cells using various methods.
What are the symptoms of local inflammation?
Redness, heat, swelling, and pain
These symptoms result from increased blood flow and vascular permeability.
What is systemic inflammation?
An exaggerated defense response of the body to a noxious stressor to localize and eliminate a source of insult
Examples of stressors include infection, trauma, and malignancy.
What is adaptive immunity?
Also known as the acquired immune system, develops when the immune system responds to a foreign substance or microorganism
This type of immunity is characterized by specificity and memory.
What are the two defining characteristics of adaptive immunity?
- Specificity
- Memory
What is humoral immunity?
Antibody-mediated immunity involving B cells that produce antibodies against specific antigens
It targets antigens from pathogens that are circulating outside of infected cells.
What are antibodies?
Soluble proteins secreted by activated B cells in response to an antigen
Antibodies specifically bind to their corresponding antigens.
What is the basic structure of an antibody?
A Y-shaped structure consisting of four amino acid chains linked by disulfide bonds
Each antibody has two heavy chains and two light chains.
What are direct effects of antibodies?
Occur when a single antibody binds to an antigen and inactivates it
This can also happen when many antigens are bound together by antibodies.
What are indirect effects of antibodies?
Activate other mechanisms to destroy the antigen after binding
This involves the constant region of the antibodies.
What is the complement mechanism in antibody action?
The chief antibody ammunition against cellular antigens, activated by binding to antibodies attached to targets
It plays a crucial role in innate defenses.
What is neutralization in antibody action?
Occurs when antibodies bind to specific sites on bacterial exotoxins or viruses
This prevents cell injury caused by these harmful agents.
What is agglutination?
An antigen-antibody reaction that occurs when mismatched blood is transfused, causing clumping
This reaction forms the basis of blood typing tests.
What is precipitation in antibody action?
Occurs when two soluble reactants form an insoluble product, the precipitate
This depends on the formation of lattices when antigen and antibody are in optimal proportions.
What is cellular immunity?
A function of cytotoxic T cells that is most effective against microorganisms living inside body cells
This type of immunity is essential for combating intracellular pathogens.
What is an antigen?
Any substance capable of mobilizing the immune system and provoking an immune response
Most antigens are large, complex molecules not normally present in the body.
What are foreign antigens?
Antigens introduced from outside the body, such as microorganisms and their chemicals
These are recognized as foreign by the immune system.
What are self-antigens?
Molecules produced by body cells to identify them as ‘self’
They help the immune system distinguish between healthy and infected cells.
What is active natural humoral immunity?
Results from natural exposure to an antigen, stimulating an immune response
This occurs, for example, when a person gets an infection.
What is active artificial humoral immunity?
Occurs when an antigen is deliberately introduced to stimulate an immune response, such as through vaccination
Vaccines are examples of this immunity.
What is passive natural humoral immunity?
Results when antibodies are transferred from a mother to her child across the placenta
This provides temporary immunity to the newborn.
What is passive artificial humoral immunity?
Involves collecting antibodies from one source and introducing them to an infected individual via injection
This provides immediate but temporary immunity.
What is immunotherapy?
A treatment that uses substances to stimulate or suppress the immune system to help fight disease
It can be used for conditions like cancer and autoimmune diseases.
