Slide Set 6: Blood and Respiratory System Flashcards
Blood makes up ____ of the ECF
1/4
Blood is intra/extracellular
extracellular
How much of of the plasma is water and proteins?
92% water
7% proteins
Plasma is identical in composition to _____
interstitial fluid
Plasma is identical in composition to interstitial fluid except for the presence of _____
plasma proteins
What is/are the most prevalent type of protein in plasma?
Albumin
What is the percentage of albumins compared to other plasma proteins?
60%
Give examples of plasma proteins
albumin
globulin
fibrinogen
transferrin
Where are the plasma proteins made?
in the liver then secreted into the blood
Which plasma protein that is not synthesized in the liver?
Type of globulins called immunoglobulins or antibodies
Where are immunoglobulins/antibodies synthesized?
synthesized and secreted by specialized blood cells rather than by the liver.
Compare the osmotic pressure of the blood plasma and the interstitial fluid
the presence of proteins in the plasma makes the osmotic pressure of the blood higher than that of the interstitial fluid.
This osmotic gradient tends to pull water from the interstitial fluid into the capillaries and off set filltration out of the capillaries created by blood pressure
What are the functions of plasma proteins?
- blood clotting
- defense against foreign invaders
- carriers for steroid hormones, cholesterol, drugs, and certain ions such as iron (Fe2 + ).
- hormones
- extracellular enzymes
What is the function of albumins?
Major contributors to colloid osmotic pressure of plasma; carriers for various substances
What is the function of globulins?
Clotting factors, enzymes, antibodies, carriers for various substances
What is the function of fibrinogen?
Forms fibrin threads essential to blood clotting
What is the function of transferrin?
Iron transport
The main 3 cellular elements found in blood
RBC (erythrocytes)
WBC (leukocytes)
Platelets (thrombocytes)
True/False
White blood cells are the only fully functional cells in the circulation
true
Red blood cells have lost their nuclei by the time they enter the blood- stream, and platelets, which also lack a nucleus, are cell fragments that have split off a relatively large parent cell known as a mega- karyocyte {mega, extremely large + karyon, kernel + -cyte, cell}.
Which blood cells don’t have a nucleus?
RBC –> lose their nuclei by the time they enter the bloodstream
Platelets
Where do platelets split off?
megakaryocytes
What is the function of RBC?
Red blood cells play a key role in transporting oxygen from lungs to tissues, and carbon dioxide from tissues to lungs.
What is the function of platelets?
Platelets are instrumental in coagulation, the process by which blood clots prevent blood loss in damaged vessels.
What is the function of WBC?
White blood cells play a key role in the body’s immune responses, defending the body against foreign invaders, such as parasites, bacteria, and viruses.
Although most white blood cells circulate through the body in the blood, their work is usually carried out in the tissues rather than in the circulatory system.
Blood contains five types of mature white blood cells:
(1) lymphocytes
(2) monocytes
(3) neutrophils
(4) eosinophils
(5) basophils.
Monocytes that leave the circulation and enter the tissues develop into ________
macrophages
Tissue basophils are called _____
mast cells
Which WBCs are phagocytic?
neutrophils
monocytes
macrophages
What is a phagocyte?
they can engulf and ingest foreign particles such as bacteria (phagocytosis)
What are lymphocytes?
they are responsible for specific immune responses directed against invaders.
Lymphocytes are sometimes called _______
immunocytes
Which WBCs are granulocytes? Why?
basophils,
eosinophils
neutrophils
because they contain cytoplasmic inclusions that give them a granular appearance.
All blood cells come from the ______
pluripotent hematopoietic stem cell
pluripotent hematopoietic stem cell is found in the
bone marrow
Blood cells are produced in the
bone marrow
What is the synthesis of blood cells is called?
Hematopoiesis
the oxygen-binding protein of red blood cells
hemoglobin
Hematopoiesis Is Controlled by ________
Cytokines
What are cytokines?
Cytokines are peptides or proteins released from one cell that affect the growth or activity of another cell
What do cytokines do?
growth factor
differentiating factor
trophic factor
erythropoietin is a ____ that controls _____
controls red blood cell synthesis
When does erythropoiesis happen?
In response to low oxygen levels
Erythropoietin (EPO) is produced in the ____
kidneys
Erythropoietin (EPO) growth or differentiation of the
Red blood cells
Explain the erythropoiesis loop
- In response to low oxygen levels the kidneys release increasing amounts of glycoprotein erythropoietin
- This in turn stimulates the bone marrow to accelerate its production of RBC
- Once levels are normalized the kidneys stop release of erythropoietin (negative feedback loop).
What is the function of leukopoiesis?
regulate leukocyte production and development,
What is hematocrit? What are the ideal values?
Hematocrit is the percentage of total blood volume
that is occupied by packed (centrifuged) red blood cells.
males –> 40-54%
females –> 37-47%
What is a Thrombopoietin (TPO) and what is its function?
is a glycoprotein that regulates the growth and maturation of megakaryocytes, the parent cells of platelets.
Where is Thrombopoietin (TPO) produced?
TPO is produced primarily in the liver but is also present in the kidney.
How is hematocrit done?
Hematocrit is determined by drawing a blood sample into a narrow capillary tube and spinning it in a centrifuge so that the heavier red blood cells go to the bottom of the sealed tube, leaving the thin “buffy layer” of lighter white blood cells and platelets in the middle, and plasma on top.
The column of packed red cells is measured, and the hematocrit value is reported as a percentage of the total sample volume.
How is the hematocrit number reported?
The column of packed red cells is measured, and the hematocrit value is reported as a percentage of the total sample volume.
PVC
Packed Cell Volume
What is the normal range of a hematocrit?
45% RBC for men
42% RBC women
In the bone marrow, committed progenitor cells differentiate through several stages into large, nucleated ________
erythroblasts
What happens when erythroblasts mature?
As erythroblasts mature, the nucleus condenses and the cell shrinks in diameter from 20 mm to about 7 mm.
What is the last stage of the erythroblast maturation?
In the last stage before maturation, the nucleus is pinched off and phagocytized by bone marrow macrophages. At the same time, other membranous organelles (such as mitochondria) break down and disappear.
The final immature cell form, called a reticulocyte, leaves the marrow and enters the circulation, where it matures into an erythrocyte in about 24 hours .
What is the final immature form of erythtoblast called before it leaves the bone marrow and enters the circulation?
reticulocyte
In the blood erythrocyte is the mature form of
reticulocyte
What is the shape of mature erythrocyte?
Mature mammalian red blood cells are biconcave disks, shaped much like jelly doughnuts with the fillling squeezed out of the middle
What are erythrocytes filled with?
enzymes and hemoglobin
True/False
RBC can carryout aerobic metabolism
red blood cells contain no mitochondria, they cannot carry out aerobic metabolism.
What is the primary source of ATP in the RBCs
Glycolysis
What are the consequences of not having a nucleus and an ER in RBCs?
Without a nucleus and endoplasmic reticulum to carry out protein synthesis, erythrocytes are unable to make new enzymes or to renew membrane components. is inability leads to an increasing loss of membrane flexibility, making older cells more fragile and likely to rupture.
Are RBCs flexible?
Despite the cytoskeleton, red cells are remarkably flexible, like a partially filled water balloon that can compress into various shapes. This is flexibility allows erythrocytes to change shape as they squeeze through the narrow capillaries of the circulation.
What happens to the RBCs when they are put in a hypertonic media?
red blood cells shrink up and develop a spiky surface when the membrane pulls tight against the cytoskeleton
What happens to the RBCs when they are put in a slightly hypotonic media?
swells and forms a sphere without disruption of its membrane integrity
A reduction in the production of RBCs can cause a serious form of anemia called ______
aplastic anemia
A reduction of WBCs causes a condition called ___________, which leaves a person open to many infection
leukopenia
A reduction in the production of plateletsis called _________, leaving a person at high risk for hemorrhage.
thrombocytopenia
Hemoglobin Synthesis requires ____
iron
What is hemoglobin?
- the main component of red blood cells, is best known for its role in oxygen transport.
- Hemoglobin (Hb) is a large, complex protein with four globular protein chains, each of which is wrapped around an iron-containing heme group
What are the isoforms that form hemoglobin
two alpha chains and two beta chains
True/False
The four heme groups in a hemoglobin molecule are identical.
True
How many heme groups does hemoglobin have?
4
Each heme group consists of
a carbon-hydrogen-nitrogen porphyrin ring with an iron atom (Fe) in the center
How is iron absorbed in our body?
Iron is absorbed in the small intestine by active transport. A carrier protein called transferrin binds iron and transports it in the blood
What is the name of the carrier protein that is responsible for the transport of iron in the blood?
transferrin
Where is heme made?
The bone marrow takes up iron and uses it to make the heme group of hemoglobin for developing red blood cells
True/False
Excess iron is stored in the body
true
in the liver
How is iron stored in the body?
Iron ingested in amounts greater than needed for hemoglobin synthesis is stored, mostly in the liver, as the molecule ferritin and its derivatives
Iron is stored as _____ in the liver
ferritin
When RBCs are broken down __________convert remnants of the heme groups to a colored pigment called ________
spleen and liver
bilirubin
Bilirubin is carried by _________ to the liver, where it is
plasma albumin
Bilirubin ,in liver then, is metabolized and incorporated into a secretion called _____
bile
Give the order of hemoglobin and iron pathway in the body
- Fe ingested from the diet
- Fe absorbed by active transport (intestine)
- Transferrin protein transports Fe in plasma.
- Bone marrow uses Fe to make hemoglobin (Hb) as part of RBC synthesis
- RBCs live about 120 days in the blood.
- Spleen destroys old RBCs and converts Hb to bilirubin.
- Bilirubin and metabolites are excreted in urine and feces.
- Liver metabolizes bilirubin and excretes it in bile
- Liver stores excess Fe as ferritin.
What is low amount of hemoglobin called in the body?
anemia
What is anemia
If hemoglobin content is too low, the blood cannot transport enough oxygen to the tissues.
What is hemolytic anemia?
the rate of red blood cell destruction exceeds the rate of red blood cell production.
What is hereditary spherocytosis?
the erythrocyte cytoskeleton does not link properly because of defective or deficient cytoskeletal proteins.
Consequently, the cells are shaped more like spheres than like biconcave disks. This disruption in the cytoskeleton results in red blood cells that rupture easily and are unable to withstand osmotic changes as well as normal cells can.
What is the defect in sickle cell disease?
is a genetic defect in which glutamate, the sixth amino acid in the 146–amino acid beta chain of hemoglobin, is replaced by valine. The result is abnormal hemoglobin (a form referred to as HbS) that crystallizes when it gives up its oxygen.
This crystallization pulls the red blood cells into a sickle shape, like a crescent moon. The sickled cells become tangled with other sickled cells as they pass through the smallest blood vessels, causing the cells to jam up and block blood ow to the tissues. This blockage creates tissue damage and pain from hypoxia.
Why is hydroxyurea administered to the sickle cell patients?
inhibits DNA synthesis. Hydroxyurea alters bone marrow function so that immature red blood cells produce the fetal form of hemoglobin (HbF) instead of adult hemoglobin. HbF interferes with the crystallization of hemoglobin, so that HbS no longer forms and the red blood cells no longer sickle.
Hereditary anemias
Membrane defects (example: hereditary spherocytosis) Enzyme defects Abnormal hemoglobin (example: sickle cell anemia)
Acquired anemias
Parasitic infections (example: malaria)
Drugs
Autoimmune reactions
Decreased RBC production can be caused by
- plastic anemia: can be caused by certain drugs or radiation
- Inadequate dietary intake of essential nutrients
- Iron deficiency (iron is required for heme production)
- Folic acid deficiency (folic acid is required for DNA synthesis)
- Vitamin B12 deficiency (B12 is required for DNA synthesis): may be due to lack of intrinsic factor for B12 absorption
One of the most common examples of an anemia that results from insufficient hemoglobin synthesis is _______
iron-deficiency anemia.
People with iron-deficiency anemia have either a ______ red blood cell count or ____ hemoglobin content in their blood.
low
(reflected in a low hematocrit)
low
smaller RBC than usual are called
microcytic
How do RBCs look in case of iron-deficiency anemia?
Their red blood cells are often smaller than usual (microcytic red blood cells), and the lower hemoglobin content may cause the cells to be paler than normal, in which case they are described as being hypochromic {hypo-, below normal; chrom-, color}.
What is Polycythemia vera?
is a stem cell dysfunction that produces too many blood cells, white as well as red. These patients may have hematocrits as high as 60–70% (normal is 37–54%). The increased number of cells causes the blood to become more viscous and thus more resistant to ow through the circulatory system
What is relative polycythemia?
the person’s red blood cell number is normal, but the hematocrit is elevated because of low plasma volume. This might occur with dehydration
What is the opposite of polycythemia?
if an athlete overhydrates, the hematocrit may decrease temporarily because of increased plasma volume.
True/False
Relative polycythemia and the opposite are pathalogical
False
In both of these situations, there is no actual pathology involving the red blood cells.
Megakaryocytes develop their formidable size by
undergoing mitosis up to seven times without undergoing nuclear or cytoplasmic division. The result is a polyploid cell with a lobed nucleus
Platelets features
Platelets are smaller than red blood cells, are colorless, and have no nucleus.
What does a platelets cytoplasm contain?
Their cytoplasm contains mitochondria, smooth endoplasmic reticulum, and many granules filled with clotting proteins and cytokines.
How long is the lifespan of a platelet?
The typical life span of a platelet is about 10 days
Are platelets always present in blood?
Platelets are always present in the blood, but they are not active unless damage occurs to the walls of the circulatory system.
What is Hemostasis?
Hemostasis {haima, blood + stasis, stoppage} is the process of keeping blood within a damaged blood vessel (The opposite of hemostasis is hemorrhage {-rrhagia, abnormal flow}.)
Hemostasis has three major steps
- vasoconstriction,
- temporary blockage of a break by a platelet plug, and
- coagulation, the formation of a clot that seals the hole until tissues are repaired.
Explain Vasoconstriction
The first step in hemostasis is immediate constriction of damaged vessels caused by vasoconstrictive paracrines released by the endothelium.
Vasoconstriction temporarily decreases blood ow and pressure within the vessel. When you put pressure on a bleeding wound, you also decrease flow within the damaged vessel.
What is the second step in hemostasis
mechanical blockage of the hole by a loose platelet plug. Plug formation begins with platelet adhesion, when platelets adhere or stick to exposed collagen in the damaged area. The adhered platelets activate, releasing cytokines into the area around the injury. These platelet factors reinforce local vasoconstriction and activate more platelets, which aggregate or stick to one an- other to form a loose platelet plug.
What is platelet adhesion?
when platelets adhere or stick to exposed collagen in the damaged area
How is the third step of hemostasis initiated and how does it proceed?
Simultaneously, exposed collagen and tissue factor (a protein-phospholipid mixture) initiate the third step, the formation of a fibrin protein mesh that stabilizes the platelet plug to form a clot.
What is fibrin?
is the end product of a series of enzymatic reactions known as the coagulation cascade
How is the clot dissolved?
Eventually, as the damaged vessel repairs itself, the clot retracts when fibrin is slowly dissolved by the enzyme plasmin.
What is thrombus?
a blood clot that adheres to the undamaged wall of a blood vessel {thrombos, a clot or lump}. A large throm- bus can block the lumen of the vessel and stop blood ow.
What are clot busters?
enzymes that can dissolve clots in arteries a er heart attacks and strokes.
How are platelets activated?
When a blood vessel wall is first damaged, exposed collagen and chemicals from endothelial cells activate platelets
Normally, the blood vessel’s endothelium separates the collage- nous matrix fibers from the circulating blood. But when the vessel is damaged, collagen is exposed, and platelets rapidly begin to adhere to it.
How do platelets adhere to collagen?
Platelets adhere to collagen with the help of integrins, membrane receptor proteins that are linked to the cytoskeleton
What happens once the platelets are bound to collagen?
Binding activates platelets so that they release the contents of their intracellular granules, including serotonin (5-hydroxytryptamine), ADP, and platelet-activating factor (PAF)
What is the function of PAF (platelet-activating factor)?
PAF sets up a positive feedback loop by activating more platelets.
It also initiates pathways that convert platelet membrane phospholipids into thromboxane A2
How do serotonin and thromboxane A2 function?
Serotonin and thromboxane A2 are vasoconstrictors. They also contribute to platelet aggregation, along with ADP and PAF. The net result is a growing platelet plug that seals the damaged vessel wall.
Is platelet aggregation positive or negative feedback mechanism?
positive
PAF sets up a positive feedback loop by activating more platelets.
If platelet aggregation is a positive feedback event, what prevents the platelet plug from continuing to form and spreading beyond the site of injury to other areas of the vessel wall?
platelets do not adhere to normal endothelium. Intact vascular endothelial cells convert their membrane lipids into prostacyclin, an eicosanoid that blocks platelet adhesion and aggregation
coagulation is divided into two pathways that eventually merge into one:
intrinsic pathway
extrinsic pathway
intrinsic pathway of coagulation
An intrinsic pathway (yellow) begins when damage to the tissue exposes collagen. The intrinsic pathway uses proteins already present in the plasma. Collagen activates the first enzyme, factor XII, to begin the cascade.
True/False
The intrinsic pathway uses proteins already present in the plasma
True
In intrinsic pathway collagen activates the first enzyme called ____ to begin the cascade
factor XII
Extrinsic pathway of coagulation
An extrinsic pathway (blue) starts when damaged tissues expose tissue factor, also called tissue thromboplastin or factor III. Tissue factor activates factor VII to begin the extrinsic pathway.
Tissue factor is also known as
thromboplastin or factor III
How does extrinisic pathway activated?
Tissue factor activates factor VII to begin the extrinsic pathway.
The intrinsic and the extrinsic pathways of coagulation unite at the _______ (green) to create ______, the enzyme that converts fibrinogen into insoluble fibrin polymers. These fibrin fibers become part of the clot.
common pathway
thrombin
What does thrombin do?
it is an enzyme that converts fibrinogen into insoluble fibrin polymers later forms the clot
What happens in the final step of the coagulation
The final step of coagulation is the conversion of fibrinogen into fibrin, a reaction catalyzed by the enzyme thrombin. The fibrin fibers weave through the platelet plug and trap red blood cells within their mesh. Active factor XIII converts fibrin into a cross-linked polymer that stabilizes the clot.
What does factor XIII do?
Active factor XIII converts fibrin into a cross-linked polymer that stabilizes the clot.
What is the inactive form of plasmin?
An inactive form of plasmin, plasminogen, is part of the clot
After coagulation, thrombin, a factor in the coagulation cascade, works with a second factor called tissue _________ to convert inactive plasminogen into plasmin.
plasminogen activator (tPA)
What is the process of the break down of fibrin?
fibrinolysis
Two mechanisms limit the extent of blood clotting within a vessel:
(1) inhibition of platelet adhesion and
(2) inhibition of the coagulation cascade and fibrin production
What are anticoagulants?
prevent coagulation from taking place
What are the two anticoagulants produced in the body that work together ?
The body produces two anticoagulants, heparin and antithrombin III, which work together to block active factors IX, X, XI, and XII.
Which factors do heparin and antithrombin III block?
active factors IX, X, XI, and XII.
What is protein C?
another anticoagulant in the body, inhibits clotting factors V and VIII
Which factors do protein C inhibit?
inhibits clotting factors V and VIII
Acetylsalicylic acid
aspirin
How does aspirin block clot formation?
It acts by inhibiting the COX enzymes that promote synthesis of the platelet activator thromboxane A2.
What is hemophilia?
The best-known coagulation disorder is hemophilia, a name given to several diseases in which one of the factors in the coagulation cascade is either defective or lacking.
Hemophilia A, a factor VIII deficiency, is the most common form, occurring in about 80% of all cases. is disease is a recessive sex-linked trait that usually affects only males.
Neutrophils
make up approximately 65% of total WBC count in a normal blood sample; highly mobile and very active phagocytic cells; capable of diapedesis (migrate out of BV and enter tissues; cytoplasmic granules contain lysosomes (imp for destruction of bacterial cells)
What is the function of Eosinophils and where are they found?
account for 2% to 5% of circulating WBCs; numerous in lining of respiratory and digestive tracts; weak phagocytes; provide protection against infections caused by parasitic worms and allergic reactions. Release anti-inflammatory substances in allergic reaction
What do Basophils contain?
account for only 0.5% to 1% of circulating WBCs; motile and capable of diapedesis; cytoplasmic granules contain histamine (inflammatory chemical) and heparin (anticoagulant)
What is the function of Lymphocyte?
smallest of the WBCs; second most numerous type of WBC; account for approximately 25% of circulating WBCs; T lymphocytes and B lymphocytes have an important role in immunity. Produced in thymus.
What is the function of T lymphocytes?
directly attack an infected or cancerous cell
What is the function of Monocytes?
largest type of leukocyte; mobile and highly phagocytic cells; ingests bacteria and cancerous cells
What is diapedesis?
migrate out of BV and enter tissues
Where are lymphocytes produced
thymus
What is the function of B lymphocytes?
B lymphocytes produce antibodies against specific antigen
Which WBC is the biggest?
Monocytes
Blood Types
Type A—antigen A on RBC
Type B—antigen B on RBC
Type AB—both antigen A and antigen B on RBC; known as universal recipient
Type O—neither antigen A nor antigen B on RBC; known as universal donor
Universal recipient
AB
Universal donor
O
The RH + blood means
The term Rh-positive blood means that the Rh antigen is present on the RBC
The RH - blood means
RBCs have no Rh antigen present
Anti-Rh antibodies
s are not normally present in blood; anti-Rh antibodies can appear in Rh-negative blood only if it has come in contact with Rh-positive RBC
The only way this can occur is by transfusion or from pregnancy
What happens if the baby’s and the mom’s blood RH antigens don’t match
Rh negative women has Rh positive fetus she will have to be treated for next pregancy in case she has another Rh positive baby. Treat with suppressive drug RhoGAM which stops mothers body from making antibodies to Rh
Rh-positive blood cells enter the mothers blood stream at delivery•If not treated the mothers body will produce anti-Rh •If the mother is not treated after the first pregnancy the anti-Rh enter the fetus blood stream and cause agglutination of RBC. –Fatal for fetus
The four primary functions of the respiratory system are
1 Exchange of gases between the atmosphere and the blood. The body brings in O2 for distribution to the tissues and eliminates CO2 waste produced by metabolism.
2 Homeostatic regulation of body pH. The lungs can alter body pH by selectively retaining or excreting CO2.
3 Protection from inhaled pathogens and irritating substances. Like all other epithelia that contact the external environment, the respiratory epithelium is well supplied with defense mechanisms to trap and destroy potentially harmful substances before they can enter the body.
4 Vocalization. Air moving across the vocal cords creates vibrations used for speech, singing, and other forms of communication.
What are the principles of the bulk flow of air?
1 Flow takes place from regions of higher pressure to regions of lower pressure
.
2 A muscular pump creates pressure gradients.
3 Resistance to air flow is in influenced primarily by the diameter of the tubes through which the air is flowing.
True/False
Flow takes place from regions of higher pressure to regions of lower pressure
True
What primarily affects the resistance to air flow?
Resistance to air flow is in influenced primarily by the diameter of the tubes through which the air is flowing.
True/False
Air and blood are both fluids.
true
What is the primary difference between air ow in the respiratory system and blood ow in the circulatory system?
Air and blood are both fluids. The primary difference be-
tween air ow in the respiratory system and blood ow in the circulatory system is that air is a less viscous, compressible mixture of gases while blood is a non-compressible liquid.
What is cellular respiration?
Cellular respiration refers to the intracellular reaction of oxygen with organic molecules to produce carbon dioxide, water, and energy in the form of ATP.
What is external respiration?
External respiration, the topic of this chapter and the next, is the movement of gases between the environment and the body’s cells.
External respiration can be subdivided into four integrated processes:
1 The exchange of air between the atmosphere and the lungs. This process is known as ventilation, or breathing. Inspiration (inhalation) is the movement of air into the lungs. Expiration (exhalation) is the movement of air out of the lungs. The mechanisms by which ventilation takes place are collectively called the mechanics of breathing.
2 The exchange of O2 and CO2 between the lungs and the blood.
3 The transport of O2 and CO2 by the blood.
4 The exchange of gases between blood and the cells.
Inspiration
Inspiration (inhalation) is the movement of air into the lungs.
Expiration
Expiration (exhalation) is the movement of air out of the lungs.
Breathing
The mechanisms by which ventilation takes place are collectively called the mechanics of breathing
What does external respiration require?
External respiration requires coordination between the respiratory and cardiovascular systems
The respiratory system consists of structures involved in ventilation and gas exchange:
airways/the conducting system
alveoli (alveolus)
bones and muscles of thorax
Airways/Conducting system
lead from the external environment to the exchange surface of the lungs.
Alveoli
a series of interconnected sacs and their associated pulmonary capillaries. these structures form the exchange surface, where oxygen moves from inhaled air to the blood, and carbon dioxide moves from the blood to air that is about to be exhaled.
The respiratory system can be divided into two parts:
upper and lower respiratory tracts
accessory structures
The upper respiratory tract consists of
the mouth, nasal cavity, pharynx, and larynx.
The lower respiratory tract consists of
the trachea, two primary bronchi {bronchos, windpipe; singular— bronchus}, their branches, and the lungs
Bones and Muscles of the Thorax
Surround the Lungs
diaphragm
intercostal muscles
sternocleidomastoids
scalenes
Pericardial sac contains the
heart
The sacs that surround the lungs
pleural sacs
pleural membrane are held together by a thin film of
pleural fluid
What is the function of the pleural fluid?
Pleural fluid serves several purposes.
1. creates a moist, slippery surface so that the opposing membranes can slide across one another as the lungs move within the thorax.
- holds the lungs tight against the thoracic wall.
- Bond between the two pleural membranes makes the lungs “stick” to the thoracic cage and holds them stretched in a partially in inflated state, even at rest.
During breathing, the upper airways and the bronchi do more than simply serve as passageways for air. They play an important role in conditioning air before it reaches the alveoli. Conditioning has three components:
1 Warming air to body temperature (37 C), so that core body temperature does not change and alveoli are not damaged by cold air;
2 Adding water vapor until the air reaches 100% humidity, so that the moist exchange epithelium does not dry out;
3 Filtering out foreign material, so that viruses, bacteria, and inorganic particles do not reach the alveoli.
Where is air filtered?
Air is filtered both in the trachea and in the bronchi.
What is the main feature of trachea and bronchi in terms of filtering the air?
These airways are lined with ciliated epithelium whose cilia are bathed in a watery saline layer
How is the saline layer produced in cilia in trachea and bronchi?
The saline is produced by epithelial cells when Cl- secreted into the lumen by apical anion channels draws Na+ into the lumen through the paracellular pathway. Movement of solute from the ECF to the lumen creates an osmotic gradient, and water follows the ions into the airways. The CFTR channel, whose malfunction causes cystic fibrosis, is one of the anion channels found on the apical surface of this epithelium
What causes cystic fibrosis?
malfunction of CFTR channel
CFTR channel
is one of the anion channels found on the apical surface of this epithelium (cilia in trachea and bronchi for filtering)
A sticky layer of mucus floats over the cilia to trap most inhaled particles larger than 2 mm. The mucus layer is secreted by ______
goblet cells in the epithelium
What is mucociliary escalator process?
The cilia beat with an upward motion that moves the mucus continuously toward the pharynx
How does mucus disable pathogens?
Mucus contains immunoglobulins that can disable many pathogens.
What happens when mucus reaches the pharynx?
Once mucus reaches the pharynx, it can be spit out (expectorated) or swallowed. For swallowed mucus, stomach acid and enzymes destroy any remaining microorganisms.
What happens in cystic fibrosis in terms of muscociliary escalator?
inadequate ion secretion decreases fluid movement in the airways. Without the saline layer, cilia be- come trapped in thick, sticky mucus. Mucus cannot be cleared, and bacteria colonize the airways, resulting in recurrent lung infections.
What is the primary function of the alveoli?
Their primary function is the exchange of gases between themselves and the blood.
What are surfactants?
Surfactant mixes with the thin fluid lining of the alveoli to aid lungs as they expand during breathing
Surfactant a lipoprotein is formed from protein and phospholipid secretions by type II cells in the wall of the alveolus
It acts to reduce surface tension and prevents alveolar collapse during exhalation
Where are surfactants produced?
type II alveolar cells
What is the function of type II alveolar cells?
synthesize and secrete a chemical known as surfactant
help minimize the amount of fluid present in the alveoli by transporting solutes, followed by water, out of the alveolar air space.
connective tissue between the alveolar epithelial cells contains ______ that create elastic recoil when lung tissue is stretched.
elastin and collagen fibers
The order of the pulmonary circulation
it begins with the pulmonary trunk, which receives low-oxygen blood from the right ventricle. The pulmonary trunk divides into two pulmonary arteries, one to each lung. Oxygenated blood from the lungs returns to the left atrium via the pulmonary veins.
True/False WHY?
The rate of blood flow through the lungs is much higher than the rate in other tissues
True
because the lungs receive the entire cardiac output of the right ventricle
True/False
The pulmonary pressure is high due to the high rate of blood flow to the lungs
False
Despite the high flow rate, pulmonary blood pressure is low. 25/8 mmHg compared to 120/80 mmHg in the body
The right ventricle does not have to pump as forcefully to create blood flow through the lungs because resistance of the pulmonary circulation is low.
How is low pressure achieved in the pulmonary circulation?
This low resistance can be attributed to the shorter total length of pulmonary blood vessels and to the distensibility and large total cross-sectional area of pulmonary arterioles.
Inspiration Occurs When Alveolar Pressure Increases/Decreases
Expiration Occurs When Alveolar Pressure Increases/Decreases
Decreases
Increases
oxygen and carbon dioxide move between alveolar air spaces and the cells of the body. The process can be divided into two components:
the exchange of gases between compartments, which requires diffusion across cell membranes,
the transport of gases in the blood
What is hypoxia?
a state of too little oxygen
If the diffusion of gases between alveoli and blood is significantly impaired, or if oxygen transport in the blood is inadequate
What is hypercapnia?
Hypoxia frequently (but not always!) goes hand in hand with hypercapnia, elevated concentrations of carbon dioxide.
To avoid hypoxia and hypercapnia, the body uses sensors that monitor arterial blood composition. These sensors respond to three regulated variables:
1 Oxygen. Arterial oxygen delivery to the cells must be adequate to support aerobic respiration and ATP production.
2 Carbon dioxide (CO2) is produced as a waste product during the citric acid cycle. Excretion of CO2 by the lungs is important for two reasons: high levels of CO2 are a central nervous system depressant, and elevated CO2 causes a state of acidosis (low pH) through the following
reaction: CO2 + H2O ∆ H2CO3 ∆ H+ + HCO3-.
3 pH. Maintaining pH homeostasis is critical to prevent denaturation of proteins. The respiratory system monitors plasma pH and uses changes in ventilation to alter pH.
What are the steps of the pulmonary gas exchange and transport?
- Oxygen enters the blood at alveolar-capillary interface.
- Oxygen is transported in blood dissolved in plasma or bound to hemoglobin inside RBCs.
- Oxygen diffuses into cells.
- CO2 diffuses out of cells.
- CO2 is trans- ported dissolved, bound to hemoglobin, or as HCO3–.
- CO2 enters alveoli at alveolar-capillary interface.
Hypoxic hypoxia
Low arterial PO2
High altitude; alveolar hypoventilation; decreased lung diffusion capacity; abnormal ventilation-perfusion ratio
Anemic hypoxia
Decreased total amount of O2 bound to hemoglobin
Blood loss; anemia (low [Hb] or altered HbO2 binding); carbon monoxide poisoning
Ischemic hypoxia
Reduced blood flow
Heart failure (whole-body hypoxia); shock (peripheral hypoxia); thrombosis (hypoxia in a single organ)
Histotoxic hypoxia
Failure of cells to use O2 because cells have been poisoned
Cyanide and other metabolic poisons
Oxyhemoglobin
HbO2 hemoglobin bound to oxygen
1 hemoglobin molecule can bind to ____ oxygen molecules
4
The amount of oxygen that binds to hemoglobin depends on two factors:
(1) the PO2 in the plasma surrounding the red blood cells and
(2) the number of potential Hb binding sites available in the red blood cells
arterial PO2 is established by:
(1) the composition of inspired air,
(2) the alveolar ventilation rate, and
(3) the efficiency of gas exchange from alveoli to blood.
In the respiratory system, contraction of the diaphragm and other muscles is initiated by a spontaneously firing network of neurons in the _______
brain stem
Neural control of ventilation model suggests that:
1 Respiratory neurons in the medulla control inspiratory and expiratory muscles.
2 Neurons in the pons integrate sensory information and interact with medullary neurons to influence ventilation.
3 The rhythmic pattern of breathing arises from a neural
network with spontaneously discharging neurons.
4 Ventilation is subject to continuous modulation by various chemoreceptor- and mechanoreceptor-linked reflexes and by higher brain centers.
Is control of breathing positive or negative feedback?
negative feedback
Sensory input of breathing
The pneumotaxic center and apneustic center of the pons receives signals from the chemoreceptors
How does the respiratory center known when to breathe?
- Sensory input: The pneumotaxic center and apneustic center of the pons receives signals from the chemo receptors
- relays to the medullary rhythmicity area (purple).
•the cerebral cortex can override the “automatic”control of breathing
What does inspiratory and expiratory areas of the medulla represent?
The inspiratory and expiratory areas of the medulla represent the medullary rhythmicity area and relay information to the respiratory muscles that drive breathing
Respiratory function includes the following
- External respiration
- Transport of gases by the blood
- Internal respiration
- Regulation of respiration
Cleft Palate
palatine bones that form hard palate fail to unite completely and only partially separate the nose and the mouth, producing difficulty in swallowing and speech (1/800)
True/False
Cleft palate is only genetic and due to a mutant gene = trisomy 13
False
can be genetic and non genetic
genetic is the mutation = trisomy 13
Tetratogenic - Cleft palate
of, relating to, or causing developmental malformations teratogenic substances teratogenic effects
corticosteroids, benzodiazepines, anticonvulsants
In cleft palate developmental defect results from
decreased migration of neural crest cell
How to inhibit or fix cleft palate?
- If there is a gap in the gum, a bone graft may be used to fill it
- 48% reduction in CLP by taking multivitamin with folic acid.
What is the function of nose in terms of breathing?
The nose is lined with hairs which serve as a filter to screen particles from the air
The turbinates provide a large mucus-covered surface over which the air must travel –moistens air.
Mucus also acts as trap for particles before the air enters the respiratory system
In the nose ______ provide a large mucus-covered surface over which the air must travel –moistens air.
the turbinates
Pharynx (throat)
Tubelike structure extending from the base of skull to the esophagus; made of muscle
Pharynx is pathway for respiratory and digestive tracts-swallow reflex closes trachea-food-esophagus
What are the three regions of pharynx?
Nasopharynx, Oropharynx, Laryngopharynx
Accessory structures of breathing includes
the oral cavity, rib cage, and diaphragm
The bronchial walls have three layers
epithelial, SM (saline mucus), and connective tissues
What are the 2 types of cells that are found in the bronchial walls?
goblet cells and ciliated cells
The pores of Kohn
are discrete holes in walls of adjacent alveoli.
Cuboidal type II alveolar cell usually forms part of aperture
Which type of cells form the alveolar wall?
Type 1 alveolar cells
What is Respiratory membrane?
the barrier between which gases are exchanged by alveolar air and blood
The respiratory membrane is composed of
alveolar epithelium, capillary endothelium, and their joined basement membrane
The surface of the respiratory membrane inside each alveolus is coated with a fluid known as
Surfactant—that reduces surface tension-produced by Type II cell
What happens during inspiration mechanically?
During inspiration, the diaphragm contracts and moves downwards, and the thoracic cavity increases in volume.
This decreases the intra-alveolar pressure so that air flows into the lungs.
Inspiration draws air into the lungs.
What happens during expiration mechanically?
During expiration, the relaxation of the diaphragm and elastic recoil of tissue decreases the thoracic volume and increases the intra-alveolar pressure.
Expiration pushes air out of the lungs
Pulmonary ventilation mechanism must establish two gas pressure gradient:
One in which the pressure within alveoli of lungs is lower than atmospheric pressure to produce inspiration
One in which the pressure in alveoli of lungs is higher than atmospheric pressure to produce expiration
Pressure gradients are established by
changes in size of thoracic cavity that are produced by contraction and relaxation of muscle
Which pressures are important in ventilation?
- Atmospheric pressure (PB)
- Alveolar pressure (PA)
- Intrapleural pressure(PIP)
Atmospheric pressure (PB)
is the air pressure of the atmosphere outside the body’s airways.
Alveolar pressure (PA)
is intrapulmonary pressure—the pressure at the far end of the internal airways.
Intrapleural pressure (PIP)
created by two membranes that surround the lungs. It is the fluid pressure of the pleural fluid between the parietal pleura (outer membrane attached to the chest wall) and visceral pleura (membrane surrounding lung
What happens during expiration and inspiration in terms of pressure?
to achieve inspiration, the higher pressure must be outside the body.
to achieve expiration, the higher pressure must be inside the body’s airways. (PB, Atmospheric [barometric] pressure; PA, alveolar pressure
Compliance
ability of pulmonary tissues to stretch, making inspiration possible
Expansion of thorax and downward movement of the diaphragm results in ________ intrapleural pressure (Pip), leading to a ______ alveolar pressure (Palv)
decreased
decreased
When does air move into the lungs?
Air moves into lungs when alveolar pressure(Palv) drops below atmospheric pressure(PB)
Why are surfactant molecules are interspersed between water molecules?
water molecules want to shrink together because water molecules are attracted to each other-this would decrease the size of the alveolus
Surfactant acts to decrease attraction between water molecules
Surfactant molecules are interspersed between water molecules and in doing so promotes expansion of the lungs, and acts against the tendency to recoil
What are alveolar macrophages?
Alveolar macrophages are the primary phagocytes of the innate immune system,
What are the functions of alveolar macrophages?
- clearing the air spaces of infectious, toxic, or allergic particles
- secretion of lysozyme, antimicrobial peptides and proteases
- through processes of phagocytosis
- alveolar macrophages can eliminate the small inocula of typical microbes which are aspirated daily in the normal host
Factors that determine the amount of oxygen that diffuses into blood:
- The total functional surface area of the respiratory membrane
- The respiratory volume
- Alveolar ventilation
Structural factors that facilitate oxygen diffusion from alveolar air to blood:
- Capillary bed
- Walls of the alveoli and capillaries form only a very thin barrier for gases to cross
- Alveolar and capillary surfaces are large
- Blood is distributed through the capillaries in a thin layer so each red blood cell comes close to alveoli
How does the negative feedback control of respiration work?
Negative feedback control of respiration. the feedback loop that operates to increase the respiratory rate in response to high plasma PCO2
What happens to respiration in case of exercise?
Increased cellular respiration during exercise causes a rise in plasma Pco2—which is detected by central chemoreceptors in the brain and perhaps peripheral chemoreceptors in the carotid sinus and aorta
Feedback information is relayed to integrators in the brainstem that respond to the increase in Pco2 above the set point value by sending nervous correction signals to the respiratory muscles, which act as effectors.
The effector muscles increase their alternate contraction and relaxation, thus increasing the rate of respiration. As the respiration rate increases, the rate of CO2 loss from the body increases and Pco2 drops accordingly. This brings the plasma Pco2 back to its set point value.
Factors that influence breathing (Changes in the Po2, Pco2and pH of arterial blood)—sensors from the nervous system provide feedback to
medullary rhythmicity area
How does medullary rhythmicity area react to changes in the PCO2?
Pco2 acts on central chemoreceptors in medulla—if it increases, result is faster breathing; if it decreases, result is slower breathing
what happens when the blood ph decreases?
A decrease in blood pH (less Co2) stimulates peripheral chemoreceptors in the carotid and aortic bodies, and even more so, the central chemoreceptors (because they are surrounded by unbuffered fluid) to slow breathing
______ (region of the brain) influences breathing by increasing or decreasing rate and strength of respiration
Cerebral cortex
What is asthma?
edema of respiratory mucosa and excessive mucus production obstruct airways.
What is chronic bronchitis?
air tubes narrow as a result of swollen tissues and excessive mucus production
What is emphysema?
walls of alveoli are torn and cannot be repaired. Alveoli fuse into large air spaces.
