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PSIO 202 Unit 2
Terms in this set (354)
3 functions of lymphatic system
1. Drain excess interstitial fluid
2. Transport dietary lipids
3. Carry out immune responses
2 Primary Lymphatic Organs
1. Red Bone Marrow
3 Secondary lymphatic organs/tissues
1. Lymph nodes
3. Lymphatic nodules/follicles
What is the purpose of lymphatic vessels?
Drain excess ISF
Close-ended lymph capillaries
Where lymphatic vessels originate, adjacent to blood capillaries
Where are lymph nodes found?
At irregular intervals along lymph vessels
What is non-specific resistance?
Lines of defense against invasion by pathogens (bacteria, viruses, fungi, environment)
4 non-specific defenses?
1. Physical barriers
What is the body's very first line of defense?
What are 5 physical barriers to pathogenic invasion?
What chemical do leukocytes/macrophages secrete in response to foreign substances?
Pyrogens - raise body temperature
Why is high fever dangerous?
Causes enzymes to denature
What does fever cause in the liver/spleen?
Sequester (lower in other body parts) iron; inhibit bacterial growth
What does fever cause in metabolism?
Increase; speed up tissue repair and production of interferons
When is inflammatory response triggered?
When body tissues are injured, prevent spread of damaging agents to other tissues
What are the 4 cardinal signs of acute inflammation?
What is the order of % of WBCs?
How do WBCs enhance innate defenses?
Attack microorganisms directly and hinder their ability to move/grow/reproduce, etc.
What is the function of neutrophils?
Defensin proteins (like antibiotics, poke holes in cell membranes)
What is the function of basophils?
Heparin, histamine, serotonin (inflammatory response)
What is the function of eosinophils?
Histaminase (slow inflammation)
Phagocytize antibody-antigen complexes
What is the function of lymphocytes?
B cells, T cells
Natural Killer cells, innate immunity by attacking microbes/cancer cells directly
What is the function of monocytes?
Arrive late but in large numbers
What are natural killer cells?
T-lymphocytes which kill tumor cells & virus-infected cells
How do natural killer cells "kill"?
Cytolysis: perforin perforates the cell membrane
What does perforin do?
Perforates cell membrane of microbes
What is reduced NK cell count associated with?
What do antimicrobial proteins do?
Attack microorganisms directly & hinder their ability to reproduce
What are 2 types of antimicrobial proteins?
What are interferons?
Proteins produced by virus-infected body cells, T-lymphocytes, NK cells, & macrophages
What do interferons do?
Alter cellular activities (->cytokines): non-specific & work against many viruses
What is the complement system?
Series of 30+ proteins that enhance antibodies, attach to antibody-antigen complexes
What do complement proteins attach to?
Antibody-antigen complexes (enhance their activity)
What is the result of the complement system?
Membrane Attack Complex (MAC), punches holes in cell membranes (also phagocytosis, inflammation)
What else does a complement protein do besides form MAC?
Attract phagocytes, stimulate phagocytosis, & inflammation
What is the pathway of C3? (complement proteins)
C3 -> C3b and C3a -> C3b enhances phagocytosis -> C5 -> C5b and C5a -> C5b, C6, C7, C8, C9 all form membrane attack complex -> destroy particles. Separately, C3a triggers mast cells (inflammation)
How can C3 be activated?
1. Classical Pathway
2. Alternative pathway
3. Lectin pathway
What is the alternative pathway?
C3 is automatically cleaved (as opposed to being cleaved in response to bacteria) in response to injury such as a cut
What is the classical pathway?
C3 is cleaved when it binds to a microbe and then splits into a and b
What is the lectin pathway?
The liver's macrophages produces lectins, which allow C3 to be triggered by the presence of fungal components
Which process is by far the primary cause of the buildup of interstitial fluid in tissues during the course of the day?
Which is not a reason why moderate fever can be beneficial?
A. Causes liver & spleen to sequester zinc and iron needed by microorganisms
B. Decreases metabolic rate which slows the growth of microbes.
C. It triggers the production of interferons by cells
Which of the following is true? The complement system...
A. Leads to the production of interferons
B. Activates secretion of perforins
C. Results in the formation of a membrane attack complex or MAC
Residual bodies are formed by which types of blood cells?
How can we assess whether there are pathogens living inside of our cells?
By somehow randomly sampling intracellular proteins
How do cells allow us to see their intracellular components?
Major histocompatibility complex (MHC) presents antigen extracellularly
Which cells might be vulnerable to intracellular infection?
Erythrocytes because they have no nucleus; only nucleated cells can present antigens
What is an adaptive immune response?
Altered cellular reactions following contact with a specific foreign organism/product/component or "antigen"
What is an antigen?
A foreign component with the ability to make the body GENerate ANTIbodies
What are 2 types of adaptive immunity?
What does a complete antigen include?
Foreign proteins, nucleic acids, some lipids, or large polysaccharides
What are 2 important functional properties of antigens?
What is immunogenicity?
Ability to stimulate proliferation of specific lymphocytes and antibodies
What is reactivity (of antigens)?
Ability to react with activated lymphocytes/antibodies released in response to them
What does Cell-mediated immunity depend on?
T-cell receptors (TCRs) expressed on the surface of T-lymphocytes
What does cell-mediated immunity defend against?
Pathogens inside the cells (e.g. viruses)
What does antibody-mediated immunity depend on?
Antigen receptors expressed on the surface of B-lymphocytes
What does antibody-mediated immunity defend against?
Antigens and pathogens in body fluids
How is lymphocyte receptor specificity developed?
Random recombination of a series of gene segments; encode for receptors on the lymphocyte
When and where does lymphocyte receptor specificity occur?
In bone marrow, during creation of leukocytes
How many receptors do lymphocytes express on their surface?
10^5; all daughter cells have identical TCRs
`What are the criteria of immune responses?
Specificity (ONE antigen per TCR)
Tolerance (self vs non-self)
Memory (second exposure)
Where are immature lymphocytes made?
Red bone marrow
Which cells become immunocompetent in the thymus?
Which cells become immunocompetent in the red bone marrow?
What does negative selection do?
Eliminates T cells that are strongly anti-self.
What does positive selection do?
Selects T cells with a weak response to self-antigens, which thus become both "immunocompetent" and "self-tolerant"
What is positive "selection"?
Strong will to live?
What is negative "selection"?
Weak will to live?
Q1: Does the immature T cell recognize self-MHC (major histocompatability complexes) proteins?
No: the cell dies
Yes: the cell continues
Q2: Is T-Cell Receptor (TCR) capable of binding to and recognizing self-peptides?
No: the cell continues, recognize self-MHC but don't recognize self-peptides (don't want to self-destruct)
Yes: the cell dies because it recognizes self-peptides
Between TCRs and MHC proteins, which vary?
TCRs. All T cells have unique TCRs. The MHC remains the same and presents the antigen.
Which proteins can only form a finite number of shapes due to folding with a low number of amino acids?
What are the "instructors" of T cells in the thymus?
What is a T Cell that can moderately bind to self-peptides and to self-MHC proteins, called?
Why are T cells with TCRs that are unable to tightly bind to proteins valuable?
1. They will never initiate an autoimmune attack on our own cells because they don't bind strongly to self-peptides
2. Randomness of design to potentially recognize proteins that aren't ours
After graduating the thymus, what 3 things could mature T cells do?
Antigen recognition with costimulation
Antigen recognition without costimulation
What happens to T cells that recognize antigens with costimulation?
Activation, proliferation, and differentiation
What happens to T cells that recognize antigens without costimulation?
Anergy (inactivation) of T cell
What happens to T cells that give the deletion signal?
T cell dies
How is a T Cell activated in lymph node after leaving the thymus?
Tight binding with antigen on dendritic cell, engaging in costimulation
How does antigen recognition with costimulation cause positive selection?
The body needs more of the cells that have recognized a foreign body, so the cells proliferate
After positive selection of T Cells and proliferation, what types can they differentiate into?
Memory helper T Cells
Active helper T Cells
What is the purpose of B Cells in cell-mediated immunity?
Act as antigen presenters for T Cells
What foreign bodies does cell-mediated immunity defend against?
Intracellular pathogens, cancer cells, tissue transplants
What is an antibody?
A soluble version of the antigen receptor of B Cells
If the Helper T Cell binds tightly to an antigen, what is it?
A foreign body
Which protein binds from cytotoxic T Cells?
CD8 (MHC 2)
Which protein binds from helper T Cells?
CD4 (MHC 1)
What happens after Cytotoxic T Cells are activated?
Active cytotoxic T Cells
Memory cytotoxic T Cells
What do active cytotoxic T Cells do?
Leave lymphatic tissue to attack invading antigens, targeting especially cells presenting the wrong antigens
What are the steps of cell-mediated immunity?
1. Antigen presentation (all nucleated cells)
2. Antigen recognition (cytotoxic t cell)
3. Activation (confirmation from helper t cells)
4. Proliferation & Differentiation
5. Destruction (cytotoxic t cells kill the cell)
What are the major roles of Antigen-Presenting Cells (APCs)
1. Engulf antigens
2. Present fragments of the antigen on their surface, so it will be recognized by T Cells
What types of cells are the major APCs?
Dendritic cells (DCs)
"Triggered" B Cells
(not the only cells, but these all do MHC 2 whereas all other nucleated cells do MHC 1 presentation)
What is the function of dendritic cells in adaptive immunity?
Migrate to lymph nodes/secondary lymphoid organs where they present antigens to T cells
When do T cells recognize antigens?
If the antigen is attached to special membrane glycoptroteins (MHC proteins)
Who are the only people who have the same MHC proteins?
Where are MHC I proteins found?
On all nucleated cells, any that are infected with an intracellular antigen
Where are MHC II proteins found?
Antigen Presenting Cells
What is the difference between MHC I and II proteins?
MHC I: cytotoxic T Cells, what is inside the cell
MHC II: helper T Cells, what is floating around outside the cell
What are the steps of Antigen Presentation via MHC I?
1. Digestion of antigen into peptide fragments
2. Synthesis of MHC-I molecules
3. Antigen peptide fragments bind to MHC-I molecules
4. Packing into vesicle
5. Surface presentation
What are the steps of Antigen Presentation via MHC II?
1. Phagocytosis of antigen
2. Digestion of antigen into fragments
3. MHC-II molecules
4. Packing into vesicle
5. Surface presentation
What sites on the antigen do T and B lymphocytes recognize?
Antigen determinants or epitopes
How can T cell receptors recognize epitopes?
Only when they are bound to an MHC molecule (antibodies can recognize epitopes alone)
What are the 2 markers on T Cells?
CD4 or CD8
What marker do helper T cells present?
What marker do cytotoxic T cells present?
CD8 (bind only to MHC I molecules)
What do costimulators cause?
Cause T Cells to complete their activation or abort activation after binding to an antigen
Without Costimulation, T Cells:
1. Become tolerant to that antigen
2. Are unable to divide
3. Do not secrete cytokines
With Costimulation, T Cells:
1. Enlarge, proliferate, form clones
2. Differentiate and perform functions according to their class (helper/cytotoxic)
What do cytokines do?
Costimulate T cells and T cell proliferation
What is the second signal needed for activation called?
Costimulation; allows you to go from recognition to activation
Where does the cytokine interleukin 1 (IL-1) come from?
Released by macrophages
What 2 things does IL-1 do by activating helper T Cells?
1. Release interleukin 2 (IL-2); release the actions of the immune system and proliferate
2. Synthesize more IL-2 receptors (autocrine signaling, positive feedback, paracrine signal to other cells )
What does IL-2 cause in T Cells?
Positive feedback T Cell division, specialization to active and memory helper T Cells
What other cytokines do helper T Cells release?
Perforin & lymphotoxin (cell toxins)
Gamma interferon (enhance macrophage function)
IL-2 is the most important
What happens to helper t cells once they become activated and recognize presented antigen?
Stimulate proliferation of other T Cells
Stimulate B cell to proliferate & differentiate (if the APC is a B cell)
Without helper t cells there is no immune response
What happens if an inactive cytotoxic T Cell tight binds an antigen from an infected body cell?
Need a costimulatory signal provided not by the infected body cell but by a helper T Cell (using IL-2)
What happens to activated cytotoxic T Cells?
Proliferation, differentiation; active and memory Cytotoxic T Cells
What is the role of Cytotoxic T Cells in cell-mediated immunity?
Kill infected cells before they can proliferate a pathogen
What are the only T cells that can directly attack and kill other cells and our own cells?
Cytotoxic T Cells
What is immune surveillance?
Tc cells circulate throughout the body in search of body cells that display the antigen to which they have been sensitized
What are the targets of Tc cells?
Cells w/intracellular bacteria or parasites
Cancer cells (which lose regulation of appropriate expression)
Foreign cells (blood transfusions/transplants)
What mechanism of Tc action causes destruction of infected cell through apoptosis?
Release of granzymes cause apoptosis of infected cell, released microbes are destroyed by a phagocyte
What mechanism of Tc action causes destruction of infected cell through cytolysis?
Release of perforin causes cytolysis, microbes are destroyed by granulysin (directly target microbes inside the cell)
What are the 4 important proteins associated with immunity?
2. CD4, CD8
3. T Cell Receptors
4. B Cell Antigen Receptors
How do B cells create unique surface proteins known as antigen receptors?
Genetic Recombination for a gene that codes for a unique surface protein (WBCs are happy to mess with their own DNA)
What is a variable region?
2 copies on each antigen receptor, which can bind to antigens
What are antibodies?
Soluble version of a specific antigen receptor which at one time belonged to 1 B Cell
What are the 5 steps of antibody-mediated immune response?
1. Antigen Presentation (done by B Cell on MHC II)
2. Antigen Recognition (Tight binding by Helper T Cell, given to B cell if tight binding)
3. Activation (of B Cell, costimulator = IL-2 from helper T Cell)
4. Proliferation & Differentiation (Memory cells, Plasma [effector] cells)
5. Destruction/Inactivation of extracellular antigen via antibody action (B cells make antibodies, bind to and inactivate antigen in body fluids)
When are B Cells activated during antibody-mediated immunity?
When a Th cell confirms that they have presented a foreign antigen (costimulation).
What is the role of plasma cells in antibody-mediated immunity?
Produce free antibodies, which have the exact same antigen-binding sites as the antigen receptor on the surface of the progenitor cell
What are antibodies used for?
Directed against pathogens in extracellular fluid
How does antigen recognition activate a B Cell?
The free antigen is brought into the cell via endocytosis, is processed, then presented by MHC II at the plasma membrane
What occurs after MHC II presents an antigen on a B Cell?
Th cell binds and recognizes/doesn't recognize the antigen piece
How many antibodies can plasma cells secrete per hour?
How long do memory B cells remain in the body?
Why are plasma cells' antibodies effective?
They have the same antigen specificity as the inactive B Cell that started the process
Which immune cells are always retained in the plasma of secondary lymphatic tissues?
Activated B Cells (Plasma Cells)
Why do we need costimulation for cytotoxic T Cells and B Cells?
You don't want to make a mistake if the signal is wrong; some of your innate proteins can be denatured by e.g. heat, and you should not be responding to your own proteins
How do antibodies destroy an antigen (and therefore the pathogen)
They inactivate and tag the antigen for destruction (they do not personally destroy it)
Antigen-antibody (immune) complexes
Clumping the antigen and antibody together through tagging of antigen, usually for macrophages to eat (for destruction mechanisms used by antibodies)
What are the 6 defensive mechanisms used by antibodies?
1. Neutralization (e.g. neutralize poison)
2. Immobilization (e.g. bind to flagella, slow them down)
3. Agglutination (e.g. clump bacteria together for macrophages, FC receptors)
4. Precipitation (e.g. pulling things together towards it, similar to agglutination)
5. Complement fixation
6. Enhancement of phagocytosis
What destruction do neutralization, agglutination, and precipitation enhance?
What does complement fixation enhance?
Phagocytosis, Inflammation, Cell lysis
What are the 5 major antibody types?
Immunoglobin G, E, D, M, and A (IgG, IgE, IgD, IgM, IgA
What is the most prevalent antibody?
IgG (75%), ability to cross placenta
What is antibody type based on?
Basis of constant regions
Which antibodies are passed through breast milk?
All of them
Which antibody will basically destroy anything and why?
IgM; 5 equal variable region antigen receptors, very useful for binding to several things
What is the first antibody that Plasma Cells produce?
What is "class switching" in terms of antibodies?
IgM becoming a different antibody, such as IgG, IgA, IgD, IgE.
Why is IgG unique?
It can cross the placenta and go basically anywhere in the body, so they are most prevalent
What is somatic hypermutation?
Plasma cell can experiment with antibodies to experiment with killing more difficult mutant foreign bodies
What is the primary response?
Following the initial contact with antigen, several days before the antibody concentration ("titer") in the serum rises, peaking 7-10 days after initial exposure
What is the secondary response?
Following re-exposure to antigen, increase in antibody titer is fast and intense; each memory cell proliferates resulting in exponential growth of antibody titer (e.g. idea behind vaccination)
What are the 2 types of acquired immunity?
What is Naturally Acquired Active Immunity?
Infection; contact with pathogen
What is Artificially Acquired Active Immunity?
Vaccine; dead or attenuated pathogens
What is Naturally Acquired Passive Immunity?
Antibodies pass from mother to fetus via placenta, or to infant via milk
What is Artificially Acquired Passive Immunity?
Injection of immune serum (gamma globulin) from someone who has already fought the infection
Which of the following is not a mechanism of antibody action?
B. Complement Fixation
C. Enhancement of apoptosis
C. Enhancement of apoptosis
Which type of antibody accounts for 75% of all antibodies, and is the only type that crosses the placenta?
Vaccination is a type of acquired immunity which is
A. Artificial & active
B. Artificial & passive
C. Natural & active
D. Natural & passive
A. Artificial & active
What are the 6 functions of the respiratory system?
1. Ventilation & gas exchange
2. Filtering, warming, & humidifying inhaled air
3. Sound production
4. Sense of smell
5. Metabolism of hormones (angiotensin converting enzyme "ACE" located in lung cells)
6. Acid-base balance
What does external respiration refer to?
Exchange of gases between the atmosphere and blood
What does internal respiration refer to?
Gas exchange between capillary blood and the cells in tissues
What does cellular respiration refer to?
Use of oxygen by cells to produce ATP by oxidizing glucose
What structures contribute mucous into the nasal cavity?
What structure separates the two nasal cavities?
External naris, septum
What lymph structures in the oropharynx help fight infection?
Palatine and lingual tonsils
What structure allows pressure to equalize in the nasopharynx?
What is the purpose of the epiglottis?
Allows food into the esophagus and air into the trachea
What is the ventricular fold?
"False" vocal cord, helps prevent things from going down the trachea
What is the vocal fold?
True vocal cords
Of all the cartilages in the respiratory system, which is the only true "ring"?
What is the purpose of the thyroid cartilage?
Protection of trachea
What is the epiglottis made of?
Elastic cartilage; only part of respiratory system that is not hyaline cartilage
Where does the esophagus sit relative to the trachea?
What are the largest of the paired cartilages in the respiratory system?
Arytenoid cartilage; primarily involved in vocalization
What muscle constricts to create more resistance in the airway?
Why would we need to create more resistance in the airway?
Coughing, yelling, etc.
Which muscle causes vocal fold to abduct?
Posteror cricoarytenoid muscle
Which muscle causes vocal fold to adduct?
Lateral cricoarytenoid muscle
Which chambers in the skull are not air-filled and therefore not lined by mucus membrane?
A. Nasal sinuses
B. Nasal meatuses
C. The middle ear
D. Organ of corti
E. All of the above are air filled
D. Organ of corti
All others are air-filled and lined by mucus membrane
Which cartilage of the larynx is both paired and is rotated by muscles that open and close the glottis?
What is the pattern of branching in the bronchial tree?
Trachea - Primary bronchi - secondary bronchi - tertiary bronchi - bronchioles - terminal bronchioles
What are bronchopulmonary segments?
Portions of the lung supplied by a tertiary bronchus
How many bronchopulmonary segments are in the right lung?
How many bronchopulmonary segments are in the left lung?
What are bronchopulmonary segments further divided into?
How are lung lobules defined?
Each terminal bronchiole supplies a single lung lobule. A small segment of lung tissue that is wrapped in connective tissue.
What is the functional unit of the lung?
Lobule (includes: respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli; pulmonary arterioles/venules; lymphatic vessels; pulmonary capillaries)
What types of fibers are found in the connective tissue surrounding lobules?
Elastic fibers; elastic structure
What fibers are lymph nodes made of?
What are alveoli?
Sac-like out-pouchings of the respiratory portion of the bronchial tree
How many alveoli in a normal lung?
What type of cells make up 97% of the alveolar wall?
Type I alveolar cells
What are the important features about Type I alveolar cells?
Thin, tight junctions that prevent fluid leakage into alveolar air spaces
How much of the alveolar wall are Type II (septal) alveolar cells?
What is the important feature of Type II alveolar cells?
Secrete surfactant to produce surface tension and help keep lungs inflated by "pulling them down'
What is the purpose of macrophages (dust cell) in alveoli?
Pick up pieces of foreign particles to keep them clean. Migrate to trachea and dispose of particles elsewhere
What flows out of the respiratory membrane and into pulmonary capillaries?
What flows out of pulmonary capillaries and into the respiratory membrane?
What is the respiratory membrane made up of?
Epithelial & capillary basement membranes, apical & basal membranes of type I alveolar cells
What is pulmonary flow?
Pulmonary circulation: pulmonary artery supplies the lung capillaries. Each lung lobule receives a branch of the pulmonary artery. Pulmonary capillaries connect the arterioles with pulmonary venules, ultimately drain into pulmonary veins
What is nutritional flow?
Lung tissue receives oxygenated blood from the bronchial arteries, which branch off the aorta
How many "holes" in the hilum region?
What does pulmonary ventilation refer to?
Alternating flow of air into and out of the lungs (due to the actions of various respiratory muscles)
What do inspiratory muscles do?
Expand the rib cage during inspiration and drive airflow into the lungs
What do expiratory muscles do?
Depress the rib cage and force air out of the lungs
What is the thoracic cage?
The skeletal portion of the thorax (includes ribs, costal cartilages, thoracic vertebrae, sternum)
What is respiratory mechanics?
Study of how the respiratory muscles move the rib cage
What is the "respiratory pump"?
The respiratory muscles, rib cage, pleural membranes, and lung elastic tissues; the result of cyclic breathing
What is the primary inspiratory muscle?
What is the purpose of external intercostals in inspiration?
Pull ribs upward and outward, expand
What is the purpose of the sternocleidomastoid in inspiration?
Elevates the sternum
What is the purpose of the scalenes in inspiration?
Elevate the top two ribs
What is the purpose of internal intercostals in forced expiration?
Pull ribs downward & inward, reduce diameter of rib cage (reduce thoracic cavity volume, increase pressure)
What is the purpose of the abdominal muscles in forced expiration?
Depress the lower ribs and elevate diaphragm by increasing abdominal pressure (reduce thoracic cavity volume, increase pressure)
What does breathing (ventilation) depend on?
Periodic pressure changes in the lungs
When does inspiration occur?
When pressure in the lungs becomes lower than the pressure in the atmosphere
When does expiration occur?
When pressure in the lungs becomes greater than the pressure in the atmosphere
What do pressure changes in the lungs depend on?
What occurs with the pleural membranes during inspiration?
Parietal pleura is pulled outward, the visceral pleura and lungs move outwards as well
What is Transpulmonary Pressure (Ptp)?
The difference between the pressure in the pleural space which surrounds the lungs (intra-pleural pressure Pip) and the pressure inside the alveoli (intra-alveolar pressure, Palv, or intrapulmonary pressure)
What is Transpulmonary Pressure (Ptp)?
Force exerted on the lungs to keep them inflated
Palv - Pip
What are the elastic properties of respiratory structures?
1. Lung tissue will always rapidly recoil inward
2. Chest wall will always recoil or spring outward
3. At FRC, forces are equal and muscles are at rest
What is functional residual capacity (FRC)?
The amount of air present in the lungs at the end of expiration- "end-expiratory lung volume"
As you inhale, what happens to Palv, Ptp, and Pip?
Palv (intrapulmonary pressure) goes down
Ptp (transpulmonary pressure) decreases
Pip (intrapleural pressure) goes up
As you exhale, what happens to Palv, Ptp, and Pip?
Palv goes back up
Pip decreases, goes back up
At rest, what is normal alveolar and intrapleural pressure?
Palv = 760 mmHg
Pip = 756
Ptp = 760-756 = 4
During inhalation, what is alveolar pressure and intrapleural pressure?
Palv = 758
Pip = 754
Ptp = 758 - 754 = 4
Why does pressure decrease in alveoli/pleura as we inhale?
Volume increases, air flows in
What happens to tissues in lung as diaphragm relaxes?
Why does pressure increase as we exhale?
Volume decreases, air must go out
During exhalation, what is the diaphragm doing?
Relaxing, pushing back up to decrease volume
During inhalation, what is the diaphragm doing?
Contracting, pulling down to increase volume
During exhalation, what is alveolar & intrapleural pressure?
Palv = 762
Pip = 756
Ptp = 762-756 = 6
What happens as lungs recoil and diaphragm relaxes?
Palv goes above atmospheric pressure
What happens in the period between breaths to the pressures?
Alveolar pressure = Atmospheric pressure
Pleural pressure < Atmospheric pressure
How does chest/lung recoil prevent lungs from deflating?
Chest recoil outwards and lung recoil inwards causes a negative pleural pressure, which pulls on lung tissue, keeps them from deflating
What is vital capacity?
The volume of air consistently moving in and out
What is residual volume?
The air that always remains in your lungs
What is expiratory reserve volume?
"extra" air breathed out during exhalation
What is total lung capacity?
All the volumes added together
What does FRC define?
The volume that fresh air must mix with in order to increase lung oxygen stores and decrease lung carbon dioxide stores
What does a large FRC indicate?
Labored breathing; may be
Obstructive lung diseases (e.g. asthma, COPD)
Stale air builds up in the lungs, need to take deeper breaths to get more fresh air to mix in with the air in lungs
What does a small FRC indicate?
Large fluctuations in O2 and CO2; may be
Inspiratory restrictive lung disease (e.g. pulmonary fibrosis, pleural fibrosis or effusion, diaphragmatic weakness)
Expiratory restrictive lung disease (e.g. ascites, obesity, pregnancy, weakness of abdominal musculature)
What does scarring of the lungs cause?
More force is needed to inflate the lungs because they are tougher (scarring = collagen fibers)
What does lung compliance refer to?
The ease at which the lungs can be inflated
What is the formula for compliance?
Compliance = change in lung volume / change in transpulmonary pressure
What does thickening or stiffening of lung tissue cause?
Decrease in compliance; fibrotic lung
What does pulmonary emphysema cause?
Increase in compliance; raises FRC. Causes connection between alveoli and bronchioles, which actually hinders breathing because it can create air pockets, less fresh air gets into small alveoli, etc. Lungs are overinflated even at rest
What is pulmonary ventilation?
A measure of the rate of lung ventilation
How is pulmonary ventilation calculated?
Pulmonary ventilation (L/min) = tidal volume (L/breath) x breathing frequency (breaths/min)
What is alveolar ventilation?
A measure of the rate at which air actually ventilates the alveoli
How is alveolar ventilation calculated?
Alveolar Ventilation (L/min) = (tidal volume - dead space volume) (L/bereath) x breathing frequency (breaths/min)
What does increasing dead space cause?
An increase in tidal volume
Transpulmonary pressure (Ptp) is equal to
A. FRC - TV
B. Residual pressure
C. Pip - Palv
D. Alveolar pressure - pleural pressure
D. Alveolar Pressure - Pleural Pressure
What is Dalton's Law?
In a mixture of gases, each gas will exert a pressure that is proportional to its concentration
What is total gas pressure?
The pressure exerted by each gas will be a function of the total gas pressure
What is pressure exerted by each gas calleD?
What is the composition of the atmosphere?
If at 2389 ft, atmospheric pressure is 700 mmHg, at an atmospheric pressure of 700 mmHg: What is Po2?
Po2 = 700 mmHg x (21/100) = 147 mmHg
Knowing that O2 is 21% of earth's atmosphere
If at 2389 ft, atmospheric pressure is 700 mmHg, at an atmpospheric pressure of 700 mmHg: what is Pn2?
Pn2 = 700 mmHg x (79/100) = ... etc
What is Po2 and Pco2 in deoxygenated blood?
Po2 = 40 mmHg
Pco2 = 45 mmHg
Why is Pco2 higher than Po2 in deoxygenated blood?
They are wastes
What is Po2 and Pco2 in oxygenated blood?
Po2 = 100 mmHg
Pco2 = 40 mmHg
Why is Po2 higher than Pco2 in oxygenated blood?
It is oxygenated by the outside air that has a higher concentration of oxygen (and some co2)
With each inspiration, how much fresh air mixes with how much FRC?
500 mL fresh air to 2400 mL FRC
What happens to [O2] and [CO2] when we inhale?
Conc O2 increases slightly and conc CO2 decreases slightly, but average alveolar values do not change very much
Volume of fresh gas inhaled is relatively small compared to FRC already contained in the lungs
What are the Conc. of O2 and CO2 in expired air?
Because O2 is removed from lungs by the blood during inspiration
What does too much blood CO2 cause?
What are partial pressures in systemic tissue cells?
Po2 = 40 mmHg
Pco2 = 45 mmHg
Where does O2 go in systemic cells?
By what mechanism does gas exchange work?
What is the Fick Method?
A way of measuring whole body O2 uptake
O2 consumption = blood flow x (tissue oxygen extraction)
= C.O. x ([O2]arterial - [O2]mixed venous)
Amount of O2 consumed/unit time
What is the Fick Relationship?
A way of measuring CO2 production by body cells
CO2 production = blood flow x (tissue CO2 production)
CO2 production = C.O. x ([CO2]mixed venous -[CO2]arterial)
What happens during cellular respiration?
Glucose becomes CO2
O2 becomes H2O
What is respiratory quotient (RQ)?
The amount of CO2 produced divided by O2 consumed
Are the amounts of oxygen consumed and carbon dioxide produced equal?
By what variable does RQ vary?
The type of nutrient being used by the cell
An organism "laying down fat" for hibernation produces more CO2 than the O2 it consumes. What would be the RQ?
Because CO2/O2 if CO2 is greater, would be more than 1.
What does RQ = for pure fat?
What does RQ = for pure carbohydrate?
During Cellular Respiration, Glucose becomes ___, and O2 becomes _____.
A. CO2, H2O
B. H2O, CO2
C. HCO3- and H+, CO2
D. O2, HCO3- and H+
A. CO2, H2O
What are the 2 forms O2 is transported in?
1. Dissolved in blood plasma (1.5% of total)
2. Bound to hemoglobin (98.5% of total)
What does the extent to which O2 binds depend on?
PO2 (partial pressure of oxygen) in the plasma
What is the oxy-hemoglobin dissociation curve?
Relationship between the extent of oxygen binding to hemoglobin and the PO2
Where is PO2 low?
Where is PO2 high?
Pulmonary capillaries, alveoli
How many heme groups are on a hemoglobin molecule?
4; can bind 4 total O2 molecules
What is the relationship between PO2 and % saturation of hemoglobin?
Oxy-hemoglobin dissociation curve: as PO2 increases, % saturation of hemoglobin will increase but it will not go past 100%
What is the approximate PO2 in systemic veins at rest?
40 mmHg, which means % saturation of hemoglobin is about 80% (deoygenated blood in systemic veins)
What is the approximate PO2 in systemic arteries at rest?
100 mmHG, which means % sat of hemoglobin is about 90% (oxygenated blood in systemic arteries). Will never go past 100%
What determines PO2 in systemic tissues?
Harder-working cells use up more O2
What is the binding/release of O2 from hemoglobin dependent on?
Is PO2 in lungs > PO2 in the blood entering pulmonary capillaries (mixed venous blood)?
Yes; lung PO2 exceeds pulmonary capillary PO2
Why does lung PO2 exceed pulmonary capillary PO2?
O2 will diffuse into the blood and bind to hemoglobin
What happens if tissue PO2 is low?
Release of O2 from hemoglobin
What happens if tissue PO2 is high?
Binding of O2 to hemoglobin
What 3 factors will change the oxyhemoglobin dissociation curve?
What is the Bohr shift?
A reduction in blood pH and increase in blood PCO2 (both cause more acidity) cause the oxyhemoglobin curve to shift to the right. Hemoglobin molecules will release more oxygen at any given PO2 because pH has gone down. Important at tissue capillaries because O2 will be more readily released where cells are working harder.
What shift does a temperature increase cause in the oxyhemoglobin dissociation curve?
A shift to the right (Bohr shift)
What shift does a PCO2 increase cause in the oxyhemoglobin dissociation curve?
A shift to the right (Bohr shift)
What happens to % sat of hemoglobin if pH decreases or increases?
It decreases or increases (respectively)
The more acidic, the more oxygen being delivered
What happens to % sat of hemoglobin if PCO2 increases or decreases?
It decreases or increases (respectively)
The higher the PCO2 the more oxygen being delivered
What happens to % sat of hemoglobin if temperature decreases or increases?
It increases or decreases (respectively)
The lower the temperature, the less oxygen being delivered (more oxygen is retained by hemoglobin)
The harder-working a tissue is, the more O2 delivered to that tissue
What are precapillary sphincters responsive to?
Changes in pH; lower pH (more acidity) causes more openness of sphincters to deliver more O2 to tissues
How much O2 can 1 g of hemoglobin bind when fully saturated?
How much hemoglobin do males and females have?
Male: 160 g Hb/L of blood
Female: 140-150 g/L
What is the saturation of arterial blood in healthy people?
Close to 100% saturated
What is anemia?
Lowered ability of blood to carry oxygen (low blood hemoglobin concentration)
What is pernicious anemia?
Enough blood cells, but lowered ability to bond enough O2 (esp with polycythemia)
What is hypoxemia?
Low blood O2 due to low blood hemoglobin saturation
E.g. climbing a mountain; have low O2 levels, can't remember the trip (but you are not anemic)
What is hypoxia? (Anemia & hypoxemia can lead to this)
Lack of adequate O2 at the tissue level
Why is CO poisoning so dangerous/
CO can come from car exhaust, tobacco smoke, etc.
Binds to Hb heme group 200-250 times more successfully than O2. Difficult to remove.
Prevents binding of O2 to get to tissues
How is CO poisoning treated?
Administer pure O2 (then wait for CO-bound hemoglobin to be replaced by the body)
Could possibly give transfusion
What compounds are formed in RBCs after CO2 binds to them?
H2CO3 (weak carbonic acid, release H+, form bicarbonate; HCO3- is the anion)
Carbaminohemoglobin (amino acid residues on hemoglobin, not on heme group, can bind to CO2 and help transport both O2 and CO2, but not in places involved in O2 transport)
How much of the total CO2 is transported in plasma as bicarbonate ions?
How much of CO2 is transported as carbaminohemoglobin?
How much of CO2 transported is just dissolved in plasma?
Increases the rate of the CO2 + H2O --> H2CO3 reaction up to a millionfold
What is the chloride shift?
Internal Respiration at systemic cells; Carbonic anhydrase converts H2CO3 to HCO3-, which can then leave the RBC cell and is exchanged 1:1 for a Cl- ion into the cell
What is the reverse chloride shift?
External Respiration at alveoli; HCO3- enters the RBC where it is converted to H2CO3, and all leaves as CO2 toward the alveolus, while the RBC takes in O2 (1:1 ratio in which Cl- ion leaves the cell)
What is O2 loading (the time-sensitiveness of O2 exchange) dependent on?
1. The rate of gas diffusion
2. The rate of blood flow through pulmonary capillaries (TRANSIT TIME)
In a healthy lung, what is the complete time of diffusion in most alveolar-capillary units?
About .25 seconds
What is transit time at rest?
0.8 seconds (plenty of time for O2 to be loaded)
As transit time in pulmonary capillaries increases, what happens to PO2?
As transit time increases, PO2 increases to about 104 mmHg
What is the difference between respiratory skeletal muscle and other skeletal muscle?
It is both automatic and voluntary
What controls automatic movement of respiratory skeletal muscle?
Inspiratory/expiratory neurons in the medulla oblongata
Where are phrenic motor neurons located?
C3-C5 spinal segments
Where are premotor inspiratory neurons located in the medulla oblongata?
Dorsal Respiratory Group (DRG)
Where are premotor expiratory neurons located in the medulla oblongata?
Ventral Respiratory Group (VRG)
What is rhythmic breathing dependent on in the medulla oblongata?
Pacemaker-like activity that alternately turn inspiratory neurons on/off; expiratory neurons are silent at rest but can be turned on if you need to breath more
During normal quiet breathing, what happens when the DRG is active? (Inspiratory Neurons)
Diaphragm & external intercostals actively contract
Normal quiet inhalation occurs
During normal quiet breathing, what happens when the DRG is inactive? (Inspiratory Neurons)
Diaphragm & external intercostals relax, elastic recoil of chest wall & lungs
Normal quiet exhalation occurs
During forceful breathing, what happens when the DRG is activated? (Inspiratory Neurons)
Diaphragm, Sternocleidomastoid, & Scalenes contract
Activation of the VRG (Expiratory Neurons) leads to Internal Intercostal & Abdominals Contract, Forceful exhalation
What specialized receptors tell the respiratory neurons about the body's needs for ventilation?
1. Pulmonary Stretch Receptors
2. Central Chemoreceptors
3. Peripheral Chemoreceptors
Where are pulmonary stretch receptors located?
Bronchi and bronchioles
What nerve innervates pulmonary stretch receptors?
Vagus, CN X
Where are the central chemoreceptors (CO2-sensitive receptors) located?
Just beneath the ventral surface of the medulla
What stimuli do central chemoreceptors respond to?
Low pH and high PCO2 in the CSF (both correspond to greater acidity)
How is low pH in the CSF caused?
CO2 diffuses into the CSF and produces H+ ions, making it more acidic
What is the control center & the effectors of the central & peripheral chemoreceptors?
Control center: Inspiratory area in medulla oblongata
Effectors: Muscles of inhalation & exhalation
What is the result of stimulating central & peripheral chemoreceptors?
Reduce PCO2, increase pH, increase PO2
What does inhibition of the DRG cause?
DRG switches from inspiration to expiration more quickly, lung inflation stops, lung deflation begins
Where are peripheral chemoreceptors located?
What stimuli do peripheral chemoreceptors respond to?
Low oxygen in arterial blood
(Low pH and high CO2 but weakly)
What nerves innervate peripheral chemoreceptors?
Glossopharyngeal IX Nerve
Vagus X Nerve
Synapse on neurons in the DRG
What happens to ventilation as PO2 increases?
Ventilation exponentially decreases
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