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237 Cards in this Set

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Where does gas exchange occur in the lungs?
Air sacs, called aveoli.
Simple diffusion of gases is directly proportional to ____ and inversely proportional to ____.
Directly proportional to the surface area available for diffusion, the driving force, and the diffusion coefficient.

Inversely proportional to the thickness of the membrane barrier.
Define lung diffusing capacity (DL).
A measurement of the lung's ability to transfer gases.
How does emphysema affect DL?
DL decreases because destruction of alveoli results in decreased surface area for gas exchange.
How does fibrosis or pulmonary edema affect DL?
DL decreases because the membrane thickness increases.
How does anemia affect DL?
DL decreases because the amount of hemoglobin in red blood cells is reduced.
How does exercise affect DL?
DL increases because additional capillaries are perfused with blood, which increases the surface area for gas exchange.
How many oxygen molecules are found per hemoglobin?
4.
What do diffusion rates of oxygen and carbon dioxide depend on?
Partial pressure differences across the membrane and the area available for diffusion.
How can diffusion of gas be increased for perfusion-limited exchange?
Blood flow must increase.
Why is oxygen diffusion restricted in fibrosis?
The thickening of the alveolar membrane increases diffusion distance.
Why is oxygen diffusion decreased in emphysema?
The surface area for diffusion of gases is decreased.
Define tidal volume (TV).
The volume inspired or expired with each normal breath.
Define inspiratory reserve volume (IRV).
The volume that can be inspired over and above the tidal volume, especially during exercise.
Define expiratory reserve volume (ERV).
The volume that can be expired after the expiration of a tidal volume.
Define anatomical dead space.
Parts of the respiratory system that don't participate in gas exchange such as the nasal passage, trachea, and bronchi.
Define physiologic dead space.
The volume of the lungs that doesn't participate in gas exchange, or alveoli that do not inflate.
Define inspiratory capacity.
The sum of tidal volume and inspiratory reserve volume (IRV).
Define functional residual capacity (FRC).
The sum expiratory reserve volume (ERV) and residual volume (RV). The volume remaining in the lungs after a tidal volume is expired. Cannot be measured by spirometry.
Define vital capacity (VC) or forced vital capacity (FVC).
The sum of tidal volume, inspiratory reserve volume (IRV), and expiratory reserve volume (ERV). The volume of air that can be forcibly expired after a maximal inspiration.
Define total lung capacity (TLC).
The sum of all four lung volumes (TV, IRV, ERV, and RV). The volume in the lungs after a maximal inspiration. Cannot be measured by spirometry.
Define forced expiratory volume (FEV1).
The volume of air that can be expired in the first second of a maximal expiration, and it is normally 80% of the forced vital capacity (FVC).
What innervates the diaphragm?
The phrenic nerve.
What is the purpose of surfactant in the lungs?
Surfactant reduces surface tension by disrupting the intermolecular forces between molecules of liquid. It prevents alveolar collapse, especially in small alveoli.
Define atelectasis.
When alveoli collapse; part or all of the lung collapses.
What cells synthesize surfactant?
Type II alveolar cells.
Describe neonatal respiratory distress syndrome.
A premature infant lacks surfactant. The infant exhibits atelectasis, or lung collapse, difficulty reinflating the lungs, and hypoxemia.
What drug is given to stimulate surfactant production?
Cortisol, or glucocorticoid.
What drives airflow?
Airflow is driven by the pressure difference between the mouth or nose and the alveoli.
Airflow is directly proportional to _____ and inversely proportional to _____.
Airflow is is directly proportional to the pressure difference between the mouth or nose and the alveoli.

Airflow is inversely proportional to airway resistance.
What is the major site of airway resistance?
The medium-sized bronchi.
How does contraction or relaxation of the bronchial smooth muscle change airway resistance?
By altering the radius of the airways.
Sympathetic stimulation _____ the airways, while parasympathetic stimulation _____ the airways.
Constricts; dilates.
What are two other factors that alter resistance to airflow?
Lung volume and viscosity or density of inspired gas.
Describe asthma.
A chronic illness involving the respiratory system in which the airway occasionally constricts, becomes inflamed, and is lined with excessive amounts of mucus. These episodes may be triggered by exposure to an environmental stimulant.
What characterized asthma?
Decreased forced vital capacity (FVC), decreased forced expiration volume (FEV1), and decreased FEV1/FVC.

It is an obstructive disease in which expiration is impaired. Air that should have been expired is not, leading to air trapping and increased functional residual capacity (FRC).
Describe chronic obstructive pulmonary disease (COPD).
A combination of chronic bronchitis and emphysema. It is an obstructive disease with increased lung compliance in which expiration is impaired.
What characterizes COPD?
It is characterized by decreased forced vital capacity (FVC), decreased forced expiratory volume (FEV1), and decreased FEV1/FVC.

Air that should have been expired is not, leading to air trapping, increased functional residual capacity (FRC), and a barrel-shaped chest.
Describe primary emphysema.
Pink puffers have mild hypoxia and normocapnia (normal carbon dioxide pressure).
Describe primary bronchitis.
Blue bloaters have sever hyoxemia with cyanosis (bluish discolaration of the skin and mucous membranes) and hypercapnia (increased carbon dioxide pressure). They have ventricular failure and systemic edema.
Describe fibrosis.
Fibrosis is a restrictive disease with decreased lung compliance in which lung inspiration is impaired
What is fibrosis characterized by?
It is characterized by a decrease in lung volume. Forced expiratory volume (FEV1) is decreased less than forced vital capacity (FVC), so FEV1/FEV is increased.
What is the only gas found in inspired air that is carried in dissolved form?
Nitrogen is the only gas that is never bound or chemically modified.
What gases are bound to proteins in the blood?
Oxygen, carbon dioxide, and carbon monoxide.
What is the most significant example of chemically modified gas in the blood?
Carbon dioxide to bicarbonate by the action of carbonic anhydrase.
Why is normal adult hemoglobin called alpha2 beta2?
Each subunits contains a hem moiety and a polypeptide chain. Two of the subunits have alpha chains and two of the subunits have beta chains.
Define oxygen capacity.
The maximum amount of oxygen that can be bound to hemoglobin. Is dependent on the hemoglobin concentration in the blood.
Define oxygen content.
The total amount of oxygen carried in the blood, including bound and dissolved oxygen. Depends of the hemoglobin concentration.
What is another name for fetal hemoglobin?
Alpha2 gama2.
Define the hemoglobin-oxygen dissociation curve.
A plot of percent saturation of hemoglobin as a function of oxygen pressure.
What are the three forms in which carbon dioxide is carried in venous blood?
Dissolved, carbaminohemoglobin, and bicarbonate (90%).
Pulmonary circulation pressure is much _____ in comparison to the systemic circulation pressure.
Lower; 15 mmHg.
Pulmonary circulation resistance is much _____ in comparison to the systemic circulation resistance.
Lower.
What happens to the distribution of pulmonary blood floor when a person is supine?
Blood flow is nearly uniform throughout the lung.
What happens to the distribution of pulmonary blood floor when a person is standing?
Blood flow is unevenly distributed because of gravity. Blood flow is lowest at the apex (zone 1) and highest at the base of the lung (zone 3).
In zone 1 of the lungs, what has the highest, medium, and lowest pressure?
Alveolar pressure > arterial pressure > venous pressure
In zone 2 of the lungs, what has the highest, medium, and lowest pressure?
Arterial pressure > alveolar pressure > venous pressure
In zone 3 of the lungs, what has the highest, medium, and lowest pressure?
Arterial pressure > venous pressure > alveolar pressure
In the lungs, hypoxia (inadequate oxygen supply) causes vaso_____.
Vasoconstriction. This redirects blood from poorly ventilated regions of the lungs to the more well ventilated regions.
What are the two main chemoreceptors for carbon dioxide, hydrogen, and oxygen?
Central chemoreceptors in the medulla and peripheral chemoreceptors in the carotid and aortic bodies.
Besides chemoreceptors, what other receptors control breathing? (4)
Lung stretch receptors
Irritant receptors
Juxtacapillary receptors
Joint and muscle receptors
What part of the brain coordinates sensory information to control breathing?
The brain stem controls the respiratory muscles and the breathing cycle.
What is the ventral respiratory group?
A column of neurons located in the ventrolateral region of the medulla that are primarily responsible for expiration. These neurons are activated during exercise, when expiration becomes an active process.
What is the apneustic center?
A portion of the lower pons which stimulates inspiration, producing a deep and prolonged inspiratory gasp (apneusis).
What is the pneumotaxic center?
A portion of the upper pons which inhibits inspiration and regulates inspiratory volume and respiratory rate.
Describe the mucus membrane of the GI tract.
The mucus membrane is composed of specialized epithelial cells for secretion or absorption.
Describe the muscularis mucosa of the GI tract.
The muscularis mucosa is the wide spread muscle fiber layer; its contraction causes a change in the surface area for secretion and absorption.
Describe the muscle layer of the GI tract.
The muscle layer is composed of inner circular and outer longitudinal muscle layers.

Circular muscle contraction decreases the diameter of the lumen of the GI tract.

Longitudinal muscle contraction causes shortening of a segment of the GI tract.
Describe the serosa or adventitia of the GI tract.
The serosa is the external peritoneal covering layer.
What are the two parasympathetic plexuses that innervate the digestive system?
Submucosal plexus of Meissner
Myenteric plexus of Auerbach
What is the function of the two digestive system plexuses?
They integrate and coordinate the motility and secretory and endocrine functions of the GI tract.
What is the purpose of efferent fibers in the GI tract?
They carry information from the brain steam and spinal cord to the GI tract.
What is the purpose of afferent fibers in the GI tract?
They carry sensory information from the GI tract back to the brain stem and spinal cord.
What parts of the GI tract does the vagus nerve (CN X) innervate?
The esophagus, stomach, pancreas, and upper parts of the intestine.
What parts of the GI tract does the pelvic splanchnic nerve (S2-S4) innervate?
The lower parts of the large intestine and pelvic organs.
Which spinal nerves are the origin of sympathetic innervation of the GI tract?
Abdominal splanchnic nerves (T5-L2)
Where do preganglionic cholinergic fibers synapse?
In the prevertebral ganglia.
Where do postganglionic adrenergic fibers synapse?
They leave the prevertebral ganglia and synapse in the myenteric and submucosal plexuses.
What are the only three parts of the GI tract that contain striated muscle?
The pharynx, upper portion of esophagus, and anal sphincter.
What happens when circular muscle contracts?
It leads to a decrease in the diameter of the segment of the GI tract.
What happens when longitudinal muscle contracts?
It leads to a decrease in the length of the segment of the GI tract.
Where does phasic contraction occur? (3)
The esophagus, gastric antrum, and small intestine. All contract and relax periodically.
Where does tonic contraction occur? (4)
The lower esophageal sphincter, the orad stomach, the ileocecal sphincter, and internal anal sphincter.
Define slow waves.
They are oscillating membrane potentials inherent to the smooth muscle cells of some parts of the GI tract. They occur spontaneously. They originate in the interstitial cells of Cajal.
Describe the mechanism of slow wave production.
Depolarization with an inward calcium current occurs during each slow wave. This brings increases the probability that action potentials will occur. These action potentials initiate contraction of the smooth muscle cells. Repolarizing phase is an outward potassium current.
Which parts of the GI tract have the highest and lowest frequency of slow waves?
The highest frequency is in the duodenum, while the lowest frequency is in the stomach.
Define spike potentials.
They are action potentials caused by the calcium-sodium channels. Spike potentials are triggered at -40mV. Resting membrane potential is about -55mV.
What might cause depolarization in the GI tract? (4)
Stretching, acetylcholine, parasympathetic stimulation, or specific gastrointestinal hormones.
What might cause hyperpolarization in the GI tract? (2)
Norepinephrine / epinephrine or sympathetic stimulation.
Define tonic contraction.
Sustained contraction of a muscle.
What ifs the function of cholecystokinin?
It increases the contractility of the gallbladder to release bile and decreases stomach contractility, to hold fats still for digestion.
Where is cholecystokin released?
The mucosa of the jejunum, in response to fats.
What is the function of secretin?
A mild inhibitory effect on GI motility to moderate acid load of the small intestine.
Where is secretin released?
The mucosa of the duodenum, in response to acid.
What is the function of gastric inhibitory peptide?
It decreases motor function (peristalsis) when the upper small intestine is already full.
Where is gastric inhibitory peptide released?
The mucosa of the upper small intestine, in response to fats.
What two types of muscles are involved in peristalsis?
Circular and longitudinal muscles.
Defects in which plexus lead to malabsorption?
Meissner's plexus.
What are the two main functions of chewing?
To lubricate and decrease the size of food particles to facilitate swallowing.
Which portion of the brain coordinates swallowing? Which specific cranial nerves are involved?
The swallowing reflex is coordinated in the medulla, specifically by the glossopharengyl nerve (CN IX) and vagus nerve (CN X).
What are the three main events involved in swallowing?
1. Nasopharynx closes and inhibits breathing
2. Laryngeal muscles contract to elevate the larynx and close the glottis
3. Peristalsis begins in the pharynx; the upper esophageal sphincter relaxes
Define gastric reflux.
The tone of the lower esophageal sphincter is decreased and gastric contents reflux into the esophagus, causing heart burn.
Define achalasia (cardiospasm).
An esophageal motility disorder where the smooth muscle loses normal peristalsis and the lower esophageal sphincter fails to relax. Causes dysphagia and decreased cell numbers in the myentric plexus (Hirschsprung's disease).
Define esophageal atresia.
The distal end of the esophagus is closed.
Define tracheoesophageal fistula.
A connection between the esophagus and trachea allows milk to enter the respiratory tract and cause severe respiratory infection.
Why is esophageal cancer more common in Iran and China?
Increased irritation of the mucosa by hot tea, opium, etc.
Define hiatal hernia.
Protrusion of part of the stomach into the mediastinum through the esophageal hiatus of the diaphragm.
Define sliding hiatus hernia.
When the abdominal part of the esophagus, cardia, and fundus slide up through the esophagial hiatus. Causes regurgitation and heart burn.
Define paraesophageal hiatus hernia.
When part of the fundus and peritonium passes through the esophageal hiatus.
What is the most common surgery used to reinforce the lower esophageal sphincter?
Funduplication, where the upper portion of the stomach is wraped around the lower portion of the esophagus and anchored below the diaphragm.
How is radiofrequency treatment used to reinforce the lower esophageal sphincter?
An endoscope with electrodes causes tiny burns at the gastroesophageal junction that heal and form scar tissue, which tightens the valve.
Define tunica muscularis.
The motor of the stomach which consists of bundles of smooth muscle fibers.
List the muscle layers of the stomach. (3)
Inner circular, outer longitudinal, and oblique.
Describe the gastric mucosa.
Gastric glands open into pits. The mucosa and pits are covered by columnar epithelium. Epithelial cells produce mucus to protect from auto-digestion.
Which cells produce gastrin?
G cells, mainly in the pyloric antrum. Gastrin stimulates acid secretion and growth of parietal cells.
Describe Zollinger-Ellison syndrome.
Gastrin is secreted by non-beta cells of the pancreas, causing multiple ulcers in the stomach.
What is the function of secretin?
Secretin inhibits HCl secretion in the duodenum.
What is the function of pepsinogen?
It is a protein splitting enzyme activated by HCl. The active form is pepsin.
Where are endocrine cells located? What four endocrine substances do they produce?
Endocrine cells of the mucus membrane are mainly in the antrum. They produce histamine, somatostatin, gastrin, and serotonin.
What do goblet cells secrete?
Mucus.
What do parietal cells secrete?
Hydrochloric acid.
What do chief / zymogenic cells secrete?
Pepsinogen.
What do enterochromaffin-like cells (ELC) secrete? Where are they found?
Histamine and seratonin (5-hydrooxytryptamine), paracrine regulators of the GI tract. ELC can be found in the stomach and intestine.
What do D cells secrete?
Somatostatin and intrinsic factor. Somatostatin can act as a paracrine regulator or a neurotransmitter.
Define the paracrine effect.
A hormone regulates other hormone production.
Define receptive relaxation.
A vagovagal reflex that is initiated by distention of the stomach; the orad region of the stomach relaxes to accommodate the ingested meal.
What hormone mediates receptive relaxation?
Cholecystokin (CCK).
Define retropulsion.
A wave of contractions closes the distal antrum; creates a back and forth motion.
Define the migrating myoelectric complex.
Contractions that occur at 90 minute intervals to clear the stomach of residual food, even during fasting. Mediated by motilin.
When food enters the stomach the _____ region relaxes and the _____ region contracts.
Orad; caudad.
When is the rate of gastric emptying fastest?
When the stomach contents are isotonic.
What might increase the rate of gastric emptying?
Fats and H+
Describe the peristaltic pump.
Intense waves force chyme through the pylorus in waves or jets.
What is vagotomy a treatment for?
Gastric ulcers that do not respond to drug therapy.
Define gastritis.
Inflammation of the gastric mucosa. Acute gastritis could be due to a direct infection, direct toxicity, steroids, non-steroid drugs, or uremia.
Define hypertrophic gastritis or Menetrier's disease.
Giant rugal folds which stimulate cancer. Mucosa is atrophic, which is associated with protein loss.
What causes gastric ulcers?
Defective mucosal barrier, commonly in the lesser curvature of the stomach.
What might happen if a gastric ulcer perforated the posterior of wall of the stomach?
Erosion of the splenic artery, leading to hemorrhage into the peritoneal cavity.
What do I cells secrete?
Cholecystokinin (CCK).
What is the function of gastric inhibitory peptide (GIP)?
It stimulates insulin release and inhibits H+ secretion by parietal cells.
What stimulates GIP secretion?
Fatty acids, amino acids, and orally administered glucose.
What inhibits somatostatin secretion?
Vagal stimulation.
What do mast cells secrete?
Histamine.
Define mumps.
Inflammation of the parotid gland caused by mumps virus (myxovirus).
What are the characteristics of saliva? (solute concentrations, tonicity, and enzymes)
High K+ and HCO3- concentration
Low Na+ and Cl- concentration
Hypotonicity
Amylase, lingual lipase, and kallikrein
What is the function of the acinus?
Acinar cells secrete initial saliva with a composition similar to plasma and isotonic.
Where is the acinus located?
The blind end of each duct. (parotid, submandibular, and sublingual)
What modifies initial saliva?
The branching duct system, lined with columnar epithelial cells.
How is saliva ejected into the mouth?
Contraction of myoepithelial cells lining the acinus and branching system.
How does parasympathetic stimulation of the facial nerve (CN VII) and glossopharengyl nerve (CN IX) affect saliva production?
It increases saliva production by increasing the transport processes in the acinar and ductal cells by causing vasodilations.
What kind of cholinergic receptors do acinar and ductal cells have?
Muscarinic. Anticholinergic drugs cause dry mouth.
How does sympathetic stimulation affect saliva production?
It increases saliva production and the growth of salivary glands.
What kind of adrenergic receptors do acinar and ductal cells have?
B2.
Intrinsic factor is co-secreted with _____.
HCl; destruction of parietal cells leads to achlorhydira (low or absent gastric acid production) and pernicious anemia.
Describe the direct pathway for H+ secretion.
The vagus nerve innervates parietal cells and stimulates H+ secretion
Describe the indirect pathway for H+ secretion.
The vagus nerve innervates the G cells and stimulates gastrin secretion, which in turn increases H+ secretion.
Why can't atropine completely block H+ secretion?
Atropine inhibits the direct pathway because it is a cholinergic muscarinic antagonist and the direct pathway uses Ach, but it cannot block the indirect pathway because it uses GRP.
How does histamine stimulate H+ secretion?
By activating H2 receptors on the parietal cell membrane.
How does cimetidine inhibit H+ secretion?
It blocks H2 receptors and inhibits histamine stimulation of H+ secretion.
Describe the cephalic phase of gastric secretion.
Triggered by sight, smell, thought, taste, and appetite. Neurological signals from the cerebrum and appetite centers travel via the parasympathetic nerves. Accounts for 20% of acid secretion.
Describe the gastric phase of gastric secretion.
Distention in the stomach causes vagovagal and enteric reflexes and activate gastrin. Accounts for 65% of acid secretion.
Describe the intestinal phase of gastric secretion.
Distension in the duodenum causes the stomach to enhance gastric fluid secretion as well as duodenum gastrin secretion.
What two negative feedback mechanisms inhibit secretion of H+ by parietal cells?
Low pH in the stomach and chyme in the duodenum.
What are four major causes of gastric ulcers?
Damage to protective barrier of the stomach
Helicobacter pylori infection, since the bacteria converts urea to ammonia and damages the gastric mucosa
Decreased H+ secretion
Increased gastrin levels (caused by low H+ secretion)
What are two major causes of duodenal ulcers?
High H+ secretion
High gastrin secretion levels
What are three substances secreted by the duodenum?
Secretin: inhibits gastric acid secretion due to high acid and fatty acids
Cholecystokin: induces gallbladder contraction in response to fatty chyme
Enterogastrone: inhibits stomach peristalsis
What sets the basic electrical rhythm (BER) of the intestine?
Slow waves, which lead to action potentials and contraction.
Why are segmental contractions important?
The back and forth movement is important for mixing and absorption without any net forward movement of the chyme.
What is the length of the small intestine involved in each segmental contraction?
1 cm.
How often do segmental contractions occur?
Every 8-12 minutes.
Propulsive contractions, or peristalsis, occur after _____ have taken place.
Digestion and absorption / segmental contractions.
What is the purpose of propulsive contractions?
Forward flow to propel the chyme though the small intestine towards the large intestine.
What is the transit time from the pylorus to the ileocecal valve?
3-5 hours.
What two systems mediate the gastroileal reflex?
The autonomic nervous system and gastrin.
Describe the gastroileal reflex.
Presence of food in the stomach triggers increased peristalsis in the ileum and relaxation of the ileocecal sphincter.
What causes the appearance of haustra?
Segmentation contractions.
How often do mass movements in the large intestine occur?
1-3 times per day.
What is the function of the ileocecal valve?
It prevents backward flow of fecal contents, especially when the proximal colon is distended with fecal matter.
Where does most water absorption occur in the large intestine?
In the proximal colon.
What percentage of water is absorbed from chyme in the large intestine?
90%.
The pancreas contains a high concentration of _____.
HCO3-, or bicarbonate.
What are the five characteristics of pancreatic secretion? (ionic concentrations, tonicity, and enzymes)
Na+ and K+ concentrations similar to plasma
High HCO3- concentration
Low Cl- concentration
Isotonic
Pancreatic amylase, lipase, and protease
What effect does secretin have on pancreatic ductal cells?
It increases HCO3- secretion to neutralize H+ in the duodenum.
What effect does cholecystokinin (CCK) have on pancreatic acinar cells?
It increases enzyme secretion in response to small peptides, amino acids, and fatty acids in the duodenum.
What is the effect of Ach (by vagovagal reflex) on pancreatic acinar cells?
It stimulates enzyme secretion in response to H+, small peptides, amino acids, and fatty acids in the duodenum.
What are the four contents of bile?
Bile salts
Phospholipids
Cholesterol
Bile pigments (bilirubin)
What type of cells produce bile?
Hepatocytes.
Define bilirubin.
Red pigments, composed from the breakdown of heme in dead red blood cells.
_____ and _____ cause contraction of the gallbladder and relaxation of the sphincter of Oddi.
CCK and Ach.
How are gallstones formed?
An imbalance in the concentration of cholesterol and bile salts leads to precipitation of the salts or cholesterol. Also called cholelithiasis.
What causes acute cholecystitis?
Cystic duct obstruction leads to bile accumulation in the gallbladder and inflammation of the gallbladder wall.
What is Murphy's sign?
Painful splinting of respiration during deep inspiration in the palpitation of the right upper quadrant, present in acute cholecystitis.
Define cholecystectomy.
Removal of the gallbladder due to severe cystic duct obstruction or cholecystitis.
What is the functional unit of the liver?
A liver lobule. The liver contains 50 to 100 thousand lobules.
_____ cells are specialized macrophage cells that ingest bacteria in portal blood.
Kupffer.
Define gluconeogenesis.
Formation of glucose from certain amino acids, lactate, or glycerol.
Define glycogenolysis.
Formation of glucose from glycogen.
Define glycogenesis.
Formation of glycogen from glucose.
List the three substances stored in the liver.
Glycogen, vitamins, and iron.
List the three substances that are detoxified or excreted by the liver.
Hormones, excess plasma calcium, and drugs.
The liver makes most plasma _____.
Proteins.
What is a common sign of liver damage?
Jaundice, a yellowing of the eyes and skin.
Define hepatitis.
Inflammation of the liver, which may be caused by viruses, poisons, autoimmunity, or hereditary conditions.
Define cirrhosis.
Formation of fibrous tissue in the liver to replace dead liver cells.
Why does cirrhosis cause the patient to present with a large belly?
Ascites is a fluid buildup in the peritonium. Cirrhosis of the liver causes retrograde, where blood flows backward though the portal vein. Plasma is absorbed by the peritonium and must be aspirated.
Cancer in the _____ often metastasizes to the liver.
Colon.
Define Wilson's disease.
A hereditary disease which causes the body to retain copper. The excess copper damages the liver and nervous system.
Define innate immunity.
Internal and external defenses that are always present in the body and represent the first line of defense against invasion by potential pathogens.
List the three major groups of phagocytic cells.
Neurotrophils
Monocytes and macrophages derived from monocytes
Organ specific phagocytes
Define chemotaxis.
Movement toward chemical attractants known as chemokines.
_____ are first to arrive at the site of an infection; _____ arrive later and can be transformed into macrophages.
Neutrophils; monocytes.
Temperature is regulated in the _____ in response to prostaglandin E2 (PGE2). PEG2 release is triggered by a _____.
Anterior hypothalamus; pyrogen
Define pyrogen.
A substance that induces fever. They can be internal (endogenous) or external (exogenous).
Activation of what pathway causes PGE2 release?
Arachidonic acid pathway.
What three enzymes mediate the arachidonic pathway?
Phospholipase A2 (PLA2), cyclooxygenase-2 (COX-2), and prostaglandin E2 (PEG2) synthase.
What type of drug is used to treat fever?
A non-steroid anti-inflammatory drug such as aspirin.
Define antigen or immunogen.
A molecule that stimulates an immune response. Usually proteins or polysaccharides, including parts of bacteria, viruses, etc. Antigens stimulate the production of specific antibodies.
Define hapten.
A small molecule which can elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one which also does not elicit an immune response by itself.
What are the three major types of lymphocytes?
T cells
B cells
Natural killer (NK) cells
How do NK cells defend the host from tumors and virally infected cells?
NK cells are activated in response to a family of cytokines called interferons. Activated NK cells release cytotoxic (cell killing) granules, which destroy altered cells.
What is the function of a T cell?
It recognizes specific antigens and activates or deactivates other immune cells.
What is the function of a B cell?
It secretes antibodies.
Most antibodies in serum are in the _____ subclass. Most of the antibodies in external secretions such as saliva and milk are in the _____ subclass. Antibodies in the _____ subclass are involved in certain allergic reactions.
IgG; IgA; IgE.
What is the purpose of antibodies?
To identify the targets for immunological attack ajd to activate immune processes that destroy the invader.
Define opsonization.
The ability of antibodies to stimulate phagocytosis.
Which complement proteins are used for recognition?
C1.
Which complement proteins are used for activation of other proteins?
C4,C2, and C3.
Which complement proteins are used to attack?
C5 through C9.
Describe the complement protein classic pathway.
IgG + IgM --> C1 --> C4 --> C4b --> C2 + C3--> C3b --> C5 --> C5a + c5b --> stimulate mast cells to release histamine + chemokine to attract neutrophils and monocytes. C5 though C9 are inserted into the bacterial cell membrane to form a membrane attack complex.
Describe the membrane attack complex.
A large pore that kills a bacterial cell through the osmotic influx of water.
Define helper T cell.
Once activated, Th cells they divide rapidly and secrete cytokines that regulate the immune response.
Define cytotoxic T cell.
Tc cells destroy virally infected cells and tumor cells.
Define memory T cell.
Persist after an infection has been revolved to provide the immune system with "memory" against past infections.
Define regulatory T cell.
Treg cells, or suppressor T cells, maintain immunologoical tolerance. They act to suppress activation of the immune system and thereby maintain immune system homeostasis and tolerance to self-antigens.
Define autoimmunity.
The failure of an organism to recognize its own constituent parts, which results in an immune response against its own cells and tissues. Ex. diabetes type 1 and dermatitis.
Define immediate hypersensitivity.
Results when an allergen provokes the production of antibodies in the IgE class. These antibodies attach to tissue mast cells and stimulate the release of histamine.
Define delayed hypersensitivity.
Cell-mediated response of T lymphocytes.