Physio Lecture 19 (Exam 3)

Front 1

How do you best describe the concentration of a particular gas in a mixture of gases such as our
atmosphere?

Back 1

The concentration of a particular gas in a mixture is defined by the partial pressure that it exerts.

Front 2

What is the partial pressure of oxygen in sea level air, in your alveoli, in your legs while sitting?

Back 2

The PO2 of oxygen in sea level air is about 160 mmHg; PO2 of oxygen in your alveoli is about 100-105 mmHg; PO2 of oxygen in your legs while sitting is about 100 mmHg at the beginning of the capillary bed and 40 mmHg at the end of the capillary bed.

Front 3

Why does the partial pressure of oxygen decrease between sea level air and you alveoli?

Back 3

It decreases, because it mixes with air in the "dead space" (or conducting zone), which has a higher concentration of CO2, so it decreases the relative
concentration of O2.

Front 4

Can your tissues have too much oxygen?

Back 4

Yes, tissues can have too much oxygen, in fact, too much oxygen can damage tissues.

Front 5

How is oxygen dissolved or carried in blood?

Back 5

Oxygen will dissolve in blood, but the majority of it is carried by the iron in the hemoglobin molecules.

Front 6

What type of molecule is hemoglobin (Hb), to what component of Hb does the O2 bind?

Back 6

Hb is a polypeptide chain, composed of 4 subunits, in normal circumstances there are two alpha and two beta peptide chains.

Front 7

How much oxygen can
plasma carry? Whole blood?

Back 7

Plasma can only carry about 3ml O2/liter, whereas whole blood can carry about 200ml O2/liter.

Front 8

Do erythrocytes have nuclei? Mitochondria?

Back 8

Mature erythrocytes have neither nuclei nor mitochondria

Front 9

Can erythrocytes metabolize aerobically?

Back 9

Mature erythrocytes have neither nuclei nor mitochondria, so they are only able to obtain energy through anaerobic respiration (glycolysis).

Front 10

What is a metabolic byproduct
of glycolysis in RBC's?

Back 10

A by-product of glycolysis in RBC's is 2,3-DPG (2,3-
diphosphoglycerate - aka 2,3-bisphosphoglyerate).

Front 11

What is the average life span of an erythrocyte?

Back 11

The average life span of an erythrocyte is about 120 days.

Front 12

What is saturated Hb?

Back 12

Saturated Hb, is hemoglobin which is "fully loaded" with oxygen - meaning that all four heme groups have oxygen associated with them.

Front 13

What is unsaturated Hb?

Back 13

Unsaturated Hb, is hemoglobin which some or all of the heme groups have no oxygen associated with them

Front 14

What is the relationship between the # of oxygens bound to Hb and the partial pressure of oxygen?

Back 14

Generally, as the partial pressure of oxygen increases, there are more and more # of oxygens bound (remember that partial pressure is basically the concentration of oxygen).

Front 15

Does Hb have a different affinity for oxygen at different partial pressure levels.

Back 15

Hb has a different affinity for oxygen at different partial pressure levels, this is because that with each additional O2 molecules that is bound, it changes the shape of the entire hemoglobin molecule so that it has a higher affinity for the next O2 bound.

Front 16

How saturated is Hb above PO2=60mmHg

Back 16

At 60mmHg Hb is about 90% saturated

Front 17

How saturated is Hb above PO2=40mmHg

Back 17

at 40mmHg it is about 75% saturated

Front 18

How saturated is Hb above PO2=20mmHg

Back 18

at 20mmHg it is about 35% saturated.

Front 19

Is the carbon dioxide level higher in the pulmonary arteries or pulmonary veins?

Back 19

carbon dioxide levels are higher in the pulmonary arteries

Front 20

Is the carbon dioxide level higher in the aorta or vena cava?

Back 20

carbon dioxide levels are higher in the vena cava

Front 21

What is the relationship between Hb saturation and pH (and temp)?

Back 21

The lower the pH or the higher the temperature the lower the Hb saturation at any given partial
pressure of oxygen.

Front 22

What other molecules or ions normally bind to Hb besides oxygen?

Back 22

Other molecules or ions that bind Hb include H+, lead, carbon monoxide, 2,3-DPG, and to a very
small extent carbon dioxide.

Front 23

How does lead or carbon
monoxide affect Hb binding of oxygen?

Back 23

Both lead and carbon dioxide bind so tightly to the iron atom of the heme group, that they prevent the iron from binding oxygen

Front 24

What happens to PCO2 and pH during hypoventilation?

Back 24

In hypoventilation, PCO2 levels increase, this increases the amount of H+ and therefore decreases the pH (respiratory acidosis).

Front 25

What happens to PCO2 and pH during hyperventilation?

Back 25

In hyperventilation, there is a decrease in PCO2, a decrease in the amount of H+, which causes an increase in pH (respiratory alkalosis).

Front 26

Do sickle cell RBC's hemoglobin bind oxygen as well as normal RBC's hemoglobin?

Back 26

Sickle cell RBC's bind oxygen as well as normal RBCs.

Front 27

Why do people with sickle cell RBC's become anemic and under what circumstances?

Back 27

people with sickle RBC's can
become anemic when the cells start to sickle in shape and can then easily break apart. The cells will sickle when they release O2, so often exercise induces the sickling, since more oxygen is unloaded from the RBC's.

Front 28

Why do sickle cell RBC's take
on an elongated shape? Are they ever normally shaped?

Back 28

They take on the elongated shape (sickle shape), because they have a heme protein
that has a change in one amino acid residue, this causes the hemoglobin molecules to come together
and form solid rod like filaments when they are not fully saturated with oxygen. When the cells are fully saturated with oxygen, they are normal shaped

Front 29

What is the major form in which CO2 is taken to the lungs?

Back 29

The major form in which CO2 is taken to the lungs is in the form of bicarbonate. The conversion of CO2 to bicarbonate occurs in the RBC, due to the presence of the enzyme carbonic anhydrase

Front 30

What is the chloride shift?

Back 30

As bicarbonate builds up in the RBC's it is transported out of the RBC by an antiporter which transports chloride into the cell as bicarbonate is transported out. This is referred to as the chloride shift.

Front 31

What is respiratory acidosis?

Back 31

Respiratory acidosis is caused by inadequate ventilation (for example hypoventilation), which results in an increase in plasma carbon dioxide.

Front 32

What is respiratory alkalosis?

Back 32

respiratory alkalosis is from hyperventilation which results in a decrease in plasma carbon dioxide concentrations.

Front 33

What molecule is the major regulator of ventilation rate?

Back 33

The major regulator of ventilation rate is carbon dioxide

Front 34

Where are the respiration control centers found in the brain?
How do these centers get information about levels of O2 or CO2 in the blood?

Back 34

There are a couple of respiration control centers: in the medulla oblongata, there is a major "rhythmicity area" which has both neurons which control both inspiration and expiration. The rhythmicity area of the medulla oblongata receives information from chemoreceptors in the medulla itself, as well as from chemoreceptors in the aortic
bodies and the carotid bodies. These chemoreceptors monitor the levels of PCO2, pH, and PO2. When any of these values change, these receptors signal for either an increase or a decrease in ventilation to
maintain fairly constant levels of all.

Front 35

What does the apneustic center do? The pneumotaxic center do?

Back 35

Presently it is not currently understood what the exact role of the apneustic and pneumotaxic centers of the pons is. These areas are believed to be able to influence the ventilation rate set by the medulla, with the apneustic center increasing ventilation rate, and the pneumotaxic center decreasing ventilation rate by inhibiting inspiration

Front 36

How does the body respond to an increase in altitude above 10,000ft?

Back 36

Initially, a person will hyperventilate, this is referred to as the "hypoxic ventilatory response", hyperventilation due to decrease in oxygen concentration. The alkalosis that is produced by blowing
off more CO2 will counter this affect. We next see that the tidal volume increases, which increases the concentration of oxygen that reaches the alveolar spaces (more air is moved out so that the concentration of O2 with the inhaled gases is not as "diluted" - you achieve a PO2 closer to what is actually in the atmosphere). Also, vasodialation occurs, which may allow the blood to become more oxygenated, since the blood flow is reduced (remember that at high altitudes the PO2 is significantly decreased in the atmosphere and therefore in the alveolar sacs, so allowing the blood to slow down will enhance fully loading the Hb molecules). With continued exposure to high altitudes, the body will respond by increasing the number of RBC's (polycythemia) and an increase in the production of
2,3-DPG helps to lower the affinity of hemoglobin for oxygen, allowing more "unloading" in the tissues.

Front 37

Partial Pressure

Back 37

Used in gas exchange and is a pressure that a particular gas in a mixture exerts independently

Front 38

Nitrogen Narcosis

Back 38

Disorder caused by high partial pressures of gases, at sea level, nitrogen is physiologically inert and it dissolves slowly in blood due to high pressures, under hyperbaric condition it takes more than an hour for dangerous amount to accumulate in which it acts like alcohol intoxication

Front 39

Decompression Sickness

Back 39

Disorder caused by high partial pressures of gases such as in deep sea diving where the amount of nitrogen dissolving in blood as diver descends decreases due to increase in PN2 and if ascent is too rapid this sickness occurs as bubbles of nitrogen gas form in tissues and enter blood, blocking small blood vessels and producing “bends”

Front 40

Hb (Hemoglobin)

Back 40

A large iron-bearing protein molecule found within erythrocytes that binds with and transports most O2 in the blood, also carries some of the CO2 and H+ in the blood, increases oxygen carrying capacity

Front 41

Heme Groups

Back 41

Iron molecule that allows groups to combine and hold oxygen, Hemoglobin contains four of these

Front 42

Fe (Iron)

Back 42

Found on Heme groups that allows groups to combine and hold oxygen, without this molecule, heme groups cannot combine with oxygen

Front 43

Oxyhemoglobin

Back 43

O2 in blood that is bound to Hb inside RBC’s

Front 44

Methemoglobin

Back 44

Contains the oxidized form of Ferric Iron, which lacks the election to bind with O2, blood normally contains a small amount of these

Front 45

Carboxyhemoglobin

Back 45

A heme group combined with carbon monoxide, bond with carbon monoxide is 210times stronger than bond with oxygen, so heme can’t bind O2, heme binds with carbon monoxide so tightly that it cannot get off which then prevents attachment of oxygen

Front 46

Carbon Monoxide

Back 46

Binds with heme group to form carboxyhemoglobin which doesn’t allow heme group to bind with oxygen

Front 47

Oxyhemoglobin Dissociation Curve

Back 47

Gives percent of Hb sites that have bound at different pressures of O2 (PO2), reflects loading and unloading of O2 in an S like curve, differences in % saturation in lungs and tissues are shown at right in a more plateau shape, and the steep part of the curve shows differences in small change in PO2 causing big changes in % saturation, factors affecting the affinity of Hb curve to the right are 1:amount of CO2 dissolved in plasma, temperature, pH and 2,3 BPG/2,3 DPG (a byproduct of glycolysis)

Front 48

BPG/D-2,3 biphosphoglycerate (DPG/2,3 diphosphoglycerate

Back 48

A byproduct of glycolysis in RBC’s, its production is increased by low O2 levels, causes Hb to have lower )2 affinity, shifting the oxyhemoglobin dissociation curve to the right

Front 49

Fetal Hemoglobin

Back 49

HbF can’t bind DPG (byproduct of glycolysis) causing it to have higher 02 affinity, the fetus has a slightly different form of hemoglobin known as HbF which holds on to O2 better then normal Hb

Front 50

Sickle-Cell Anemia

Back 50

Affects 8-11% af. Am., HbS has valine substituted glutamic acid, an altered form of hemoglobin, HbS crosslinks to form a paracrystalline gel inside RBC’s which makes RBC’s less flexible and more fragile, low PO2 cause hemoglobin groups to join together and as O2 is taken from them they form a elongated shape when it should normally look donut like, this donut shape is important for RBC’s to be able to fit through capillaries and the elongated shape they get stuck and pressures causes them to break open causing anemia

Front 51

Myoglobin

Back 51

A red pigment found exclusively in striated muscle (slow twitch skeletal and cardiac muscle fibers)

Front 52

Carbaminohemoglobin

Back 52

Blood containing dissolved CO2 being transported, contains about 10% of CO2

Front 53

Carbonic Acid

Back 53

Formed from CO2 and H20, which is a weak acid and can dissociate into ions, but does not change pH of fluid, produced in RBC’s by carbonic anhydrase, representing H2CO3

Front 54

Bicarbonate Ion

Back 54

The anion resulting from dissociation of carbonic acid, HCO3

Front 55

CA (Carbonic Anhydrase)

Back 55

The enzyme that catalyzes the conversion of CO2 and H2O into carbonic acid, H2CO3

Front 56

Chloride Shift

Back 56

The creation of bicarbonate ions and chloride and hydrogen within the tissues to help with the balancing of pH levels within the blood

Front 57

Reverse Chloride Shift

Back 57

Opposite effect of chloride shift in which hydrogen, chloride, and bicarbonate ions are used to rebalance pH levels within the blood

Front 58

Acid

Back 58

Less then 7.0

Front 59

Base

Back 59

Greater then 7.0

Front 60

Buffer

Back 60

Most important buffer in blood is bicarbonate ion

Front 61

Volatile Acid

Back 61

Can be converted to a gas, ex: CO2 in bicarbonate buffer system can be breather out

Front 62

Non-Volatile Acid

Back 62

Cannot leave the blood, all other acids in the blood besides CO2, Ex: lactic acid, fatty acids, ketone bodies

Front 63

Respiratory Acidosis

Back 63

Caused by hypoventilation, causes ride in blood CO2 and thus carbonic acid

Front 64

Respiratory Alkalosis

Back 64

Caused by hyperventilation, results in too little CO2

Front 65

Metabolic Acidosis

Back 65

Results from excess of nonvolatile acids Es: excess of uncontrolled ketone bodies in diabetes or loss of HCO3 (for buffereing) in diarrhea

Front 66

Metabolic Alkalosis

Back 66

Caused by too much HCO3 or too little nonvolatile acids Ex: from vomiting out stomach acid)

Front 67

Rhythmicity Center

Back 67

Found within the medulla/brain stem, and is used in the control rates of ventilation that respond to chemoreceptors

Front 68

Chemoreceptors

Back 68

Respond to amount of CO2 in the blood

Front 69

Central Chemoreceptores

Back 69

Receptors located in the medulla near the respiratory center that respond to changes in ECF H+ concentration resulting from changes in arterial PCO2 and adjust respiratory accordingly

Front 70

Peripheral Chemoreceptor

Back 70

Respond to the levels of H+ cations only

Front 71

Aortic Bodies

Back 71

Respond to hydrogen ions and O2 molecules that signal either peripheral chemoreceptors or chemoreceptors

Front 72

Carotid Bodies

Back 72

Respond to hydrogen ions and O2 molecules that signal either peripheral chemoreceptors or chemoreceptors

Front 73

Hypocapnia

Back 73

Below normal arterial PCO2 levels, is brought about by hyperventilation

Front 74

Hypercapnia

Back 74

Excess CO2 in arterial blood, caused by hypoventilation

Front 75

Hypoxemia

Back 75

Above normal arterial PO2, cannot occur when a person is breathing atmospheric air at sea level,