the respiratory system part c (22c)

Hypothalamus and limbic system modify rate and depth of respiration in response to

strong emotions or pain: Breath holding in anger, Gasping with pain or fear, Increased respiratory rate when excited

Declining Po 2 has only minor effect on ventilation because...?

there is huge O 2 reservoir bound to Hb; Hb remains almost fully saturated until Po 2 falls below 60 mm Hg

Unloading of one O 2 makes it easier to

unload the next

*Ability of bronchioles to regulate airflow + ability of arterioles to regulate blood flow =

ventilation/perfusion coupling

VRG

ventral respiratory group

Cerebral motor cortex can exert___________________ ________________ over breathing and bypass...?

voluntary; medullary controls-->voluntarily hold breath

because heat is a byproduct of metabolic activities, we would expect that active tissues are _________than less active tissues

warmer

Decreased blood pH (acidosis) and increased Pco 2 cause Hb O 2 bond to________________; this is referred to as..?

weaken; Bohr effect-->O2 unloading occurs where needed most

VRG is a medullary respiratory center; what is it?

Sets normal respiratory rate and rhythm->Eupnea (12 16 breaths/minute)-->Rhythm generating and integrative center

why do all areas of lungs not have the same amount of O 2 & CO 2 and same blood flow at same time

Some alveoli are well ventilated and some are not, Some regions of lung have sufficient blood moving, through capillaries and some do not, Due to gravity causing regional variations and occasional alveolar ducts plugged with mucus

Hering Breuer Reflex (inflation reflex)

Stretch receptors in pleurae and airways are stimulated by lung inflation

Smooth muscle of bronchioles leading to alveoli and Smooth muscle of arterioles carrying blood to pulmonary capillaries can do what to maximize gas exchange

contract or relax

hypoxia causes______________, which is what?

cyanosis bluish cast seen when Hb saturation falls below 75%

rapid, deep breathing means what in terms of blood pH?

decreased CO2 in blood and a rise in pH

decreased body temp does what to respiratory rate

decreases-->apnea if you jump into cold water

In pulmonary capillaries in lungs CO2

diffuses down its pressure gradient Out of RBC and into plasma, and From plasma and into alveoli

reduced surface area=

emphysema, tumors, inflammation, mucus

why does the respiratory membrane have a large total surface area (40 times that of skin)?

for gas exchange

In the lungs, where PO 2 is high (100 mm Hg), Hb is almost

fully saturated (98%)

***Rising CO2 and H + levels in the brain are the most

important and powerful respiratory stimulant***

what happens when cells metabolize glucose and use O2 and release CO2?

increase Pco2 in capillary blood and increases in H+ in capillary blood

slow, shallow breathing means what in terms of blood pH?

increased CO2 and drop in pH

what happens when ventilation is greater than perfusion?

increased O2 and decreased Co2 in alveoli

increased body temp does what to respiratory rate?

increases

because pontine respiratory centers Influence and modify activity of VRG, this provides for a smooth transition between..?

inspiration and expiration

In the tissues of other organs, Where P O 2 is low (40 mm Hg), Hb is

less saturated with O2 (75%)

Partial pressure gradient for CO 2 in lungs is _____steep than pressure gradient for O2 in lungs

less; Pulmonary artery Pco 2 = 45 mm Hg and Alveolar Pco 2 = 40 mm Hg

In metabolically active tissues (e. exercising muscle), the P O 2 is even____________.At a P O 2 of 20 mm Hg, Hb is only 40% saturated an additional 35% of O 2 has been unloaded for tissue use.

lower

because tissue cells use O2 for metabolism, tissue Po2 is___________than in systemic arterial blood-->

lower; oxygen diffuses from blood to tissues (40 mm Hg versus 100 mm Hg)

ventilation and perfusion must be_______/___________for efficient gas exchange, what is this called?

matched/coupled; ventilation-perfusion coupling

In pulmonary capillaries in lungs, HCO3

reenters RBCs (while Cl moves out) and Binds with H to form H 2 CO 3

*Control of breathing during rest is aimed primarily at

regulating the H concentration ( Pco 2 in the brain*

If arterial Po 2 falls below 60 mm Hg , it becomes major stimulus for

respiration via peripheral chemoreceptors

Several factors can influence activity of

respiratory centers; Most important are changing arterial levels of CO2, O2, and H+

in internal respiration, partial gradients are________________compared to external respiration

reversed

in Hering Breuer Reflex (inflation reflex), vagus nerve sends...?

sends inhibitory signals to medullary respiratory centers to end inhalation/allow expiration; Protective response to prevent over inflation of lungs

At high P O 2, large changes in P O 2 cause___________changes in Hb saturation

small

why does decreased alveolar O2 case arterioles to constrict?

so effort is not wasted on these alveoli

In pulmonary capillaries in lungs, carbonic anhydrase

splits H 2 CO 3 into CO 2 and water

partial pressure gradient for O2 in lungs is

steep (Pulmonary artery Po 2 = 40 mm Hg and Alveolar Po 2 = 104 mm Hg)

Substantial drop in arterial Po 2 (to 60 mm Hg) is required to

stimulate increased ventilation

pulmonary gas exchange (external respiration) is influenced by 3 factors:

Thickness and surface area of the respiratory membrane, Partial pressure gradients and gas solubilities, Ventilation perfusion coupling

In systemic capillaries at tissues HCO 3 diffuses from RBCs into plasma and Transported to lungs to..?

To counter balance rush of HCO 3 out of RBCs->chloride shift occurs (plasma to RBCs)

apnea

breathing cessation/stopping from abnormally low Pco 2; When Pco 2 is abnormally low, respiration is inhibited and becomes slow and shallow

Changes in Pco 2 in alveoli cause changes in diameter of

bronchioles

change in arterial levels of O2, CO2, and H+ are sensed by...?

central & peripheral chemoreceptors

hemoglobin that has released O2=reduced Hb=

deoxyhemoglobin (HHb)

DRG

diagnostic related group

because metabolism produces CO2, tissue Pco2 is_____________than in blood

higher; CO2 diffuses from tissues to blood (45 mm Hg versus 40 mm Hg)

blood flow is greatest around alveoli with

highest Po2

hypoxia

inadequate O 2 delivery to tissues

PCO2 is the most

potent and closely controlled

Increase in temperature, Pco 2 , H + , BPG does what in terms of Hb?

Lowers Hb's affinity for O 2; Enhances O 2 unloading from blood

Temperature, blood pH, Pco 2 , and BPG have what effect on hemoglobin?

Modify Hb's three dimensional structure and ultimately Change Hb's affinity for O 2

O 2 is carried in blood in two ways:

1.5% dissolved in plasma (not very soluble in H 2 O) and 98.5% bound to Fe of hemoglobin ( Hb ) in RBCs 4 O 2 per Hb

partially saturated hemoglobin

3 bound O2

CO2 is transported by blood in _______ways, these are:

3; -7 to 10% dissolved in plasma, 20% bound to globin of hemoglobin carbaminohemoglobin, and 70% transported as bicarbonate ions (HCO 3 --) in plasma

fully saturated hemoglobin

4 bound O2

why does decreased alveolar CO2 cause bronchioles constrict

Allows "postponement" of elimination

Perfusion Is Controlled by

Alveolar Po2

oxygen diffusion (O2 loading)

Alveolar chamber->alveolar type I cell membrane->basement membrane of alveolus->basement membrane of capillary->capillary endothelial cell membrane->plasma and red blood cell membrane

components of the respiratory membrane

Alveolar epithelium and its basement membrane, Capillary endothelium and its basement membrane, Two basement membranes are fused

Peripheral chemoreceptors sense arterial O 2 via....?

Aortic bodies in aortic arch and Carotid bodies* at bifurcation of common carotid artery ( main oxygen sensors

CO2 diffuses from blood to alveoli but not as quickly as O2, how does it diffuse in equal amounts with oxygen?

CO 2 is 20 times more soluble in plasma than O 2

Decreased pH may be caused by ____________ _____________or other metabolic factors including:

CO 2 retention, Accumulation of lactic acid (exercise), Excess ketone bodies (diabetes)

change in arterial levels of O2, CO2, and H+ are sensed by central & peripheral chemoreceptors, what do these include?

Central: throughout brainstem, including medulla Peripheral sensitive to arterial O 2 levels; Aortic bodies in aortic arch and Carotid bodies* at bifurcation of common carotid arteries

If H concentration in blood rises (low pH), excess H+ is removed by (Carbonic acid bicarbonate buffer system)

Combining with HCO 3 to form H 2 CO 3->raises blood pH

what happens when ventilation is less than perfusion?

Decreased O 2 and increased CO 2 in alveoli

why is it good that pontine respiratory centers Influence and modify activity of VRG, this provides for a smooth transition between inspiration and expiration?

Erratic breathing results if PRC damaged Prolonged inspiration = apneustic breathing

in expiration, what does VRG do?

Expiratory neurons inhibit inspiratory neurons and Result in relaxation of respiratory muscles

If H concentration in blood drops (high pH), it is lowered when (Carbonic acid bicarbonate buffer system)

H 2 CO 3 dissociates; Releases H +-> lowers blood pH

internal respiration

Gas exchange between systemic capillaries and body tissues

what happens when pH drops?

H stimulates central chemoreceptors of brain stem, Chemoreceptors synapse with respiratory centers, rate and depth of breathing increases, flushes CO 2 out of blood lowers blood Pco2, and blood pH rises

increased heat in active tissues decreases______affinity for____________, why?

Hb for O2; allows increased O2 unloading in active tissues

At low P O 2, large changes in P O 2 cause large changes in

Hb saturation

Hb remains saturated even at high altitude or with lung disease, why?

Hb's properties produce a safety margin that ensures that Hb is almost fully saturated even with a substantial PO 2 decrease.

why is ***PCO2 the most closely controlled?

If blood Pco 2 levels rise (hypercapnia ), CO 2 accumulates in brain, and eventually pH drops and acidosis becomes nearer

Hyperventilation

Increase in rate and depth of breathing that exceeds body's need to remove CO 2

why are ***Rising CO2 and H + levels in the brain are the most important and powerful respiratory stimulant***

Increased blood CO 2-> increased CO 2 in brain->forms carbonic acid ->dissociates->releases H +->brain pH drops->central chemoreceptors respond-> send impulses to respiratory centers in brainstem->increases rate and depth of breathing to blow off CO 2

decrease in temperature, Pco2, H+, and BPG does what in terms of Hb?

Increases Hb's affinity for O 2 and Decreases O 2 unloading from blood

DRG does what?

Integrates input from peripheral stretch and chemoreceptors and Sends information to VRG

Control of Respiration involves

Involves higher brain centers, chemoreceptors, and other reflexes->Neurons in reticular formation of Medulla oblongata and Pons

pulmonary gas exchange of________and____________across the....?

O2 and CO2 across the respiratory membrane

the respiratory membrane is a thin barrier that..?

O2 and CO2 diffuse across

"Other Factors" are highest in systemic capillaries where

O2 loading is wanted

why does The amount of oxygen carried by hemoglobin depend on the amount of oxygen (P O2 ) available

P O2 measurements indicate only the amount of O 2 dissolved in plasma and not the amount bound to hemoglobin->This ensures optimal oxygen pickup and delivery

• Rate of loading (binding) and unloading (releasing) of O 2 is regulated by

Po 2, Temperature, Blood pH, Pco 2, Blood concentration of BPG

how do pulmonary irritant reflexes influence respiration?

Receptors in bronchioles respond to irritants Communicate with respiratory centers via vagal nerve and Promote reflex constriction of air passages->Receptors in upper airways initiate cough in trachea or bronchi or sneeze in nasal cavity

carbon dioxide diffusion (CO2 unloading)

Red blood cell membrane and plasma->capillary endothelial cell membrane->basement membrane of capillary->basement membrane of alveolus->alveolar type I cell membrane->alveolar chamber

why does increased alveolar O2 cause arterioles dilate

To pick up O 2 and deliver it to tissues

hypoxia can happen due to a variety of causes, including:

Too few RBCs, Abnormal or too little Hb, Blocked circulation (ischemia), Metabolic poisons (cyanide), Pulmonary disease, Carbon monoxide poisoning (red color)

pontine respiratory centers influence and modify activity of?

VRG

how could emphysema cause reduced surface area of the respiratory membrane

Walls of adjacent alveoli break down and Alveolar chambers enlarge

like blood in the CV system, oxygen in te respiratory system also diffuses down..?

a pressure gradient->from alveoli into pulmonary capillaries

why does increased alveolar CO2 cause bronchioles to dilate?

allows CO2 to be eliminated more rapidly

O2 diffuses from___________to__________

alveoli to blood

perfusion

amount of blood flow to alveoli

ventilation

amount of gas reaching alveoli

how could tumors, inflammation, or mucus cause reduced surface area

blocks gas flow into alveoli and decreases number of functional alveoli

even though cerebral motor cortex can exert voluntary controls over breathing and bypass medullary controls, the brain stem reinstates breathing when...?

blood CO 2 critical; this is why Drowning victims usually have water in their lungs

Carbonic acid bicarbonate buffer system resists changes in

blood pH

Changes in respiratory rate and depth affect

blood pH

CO2 diffuses from___________to_____________

blood to alveoli

arterial pH can modify respiratory rate and rhythm even if CO 2 and O 2 levels are normal, how is this mediated?

by peripheral chemoreceptors

CO 2 combines with water to form____________ ___________(H 2 CO 3 ), which quickly dissociates

carbonic acid-->transport and exchange of CO2

when hyperventilation occurs, this causes decreased CO2 levels-->hypocapnia, which can result in..?

cerebral vasoconstriction and ischemia, dizziness, fainting

pontine respiratory centers transmit impulses to_________________and______________-____________________breathing rhythms during...?

modify and fine-tine; vocalization, sleep, exercise

arterial pH can..?

modify respiratory rate and rhythm even if CO 2 and O 2 levels are normal

alveolar Po2 directs blood to respiratory areas where alveolar oxygen is high for...?

more efficient gas exchange

The amount of oxygen carried by hemoglobin depends on the amount of

oxygen available

in the event that Hb saturation is low, Hb's properties ensure that

oxygen is delivered where it is most needed->when tissues need more, they get more.

hemoglobin+bound O2=

oxyhemoglobin (HbO2)

Respiratory system controls attempt to raise pH by

pH by increasing respiratory rate/depth to eliminate CO 2 from blood

Decreased arterial pH caused by CO 2 retention or metabolic factors act via_______________ ____________ to...?

peripheral chemoreceptors to increase respiratory rate and depth

VRG inspiratory neyrons send impulses via____________and__________nerves to cause contraction of corresponding muscles

phrenic and intercostal (external)

transport and exchange of CO2 occurs in __________, but primarily in RBCs because..?

plasma; RBCs contain carbonic anhydrase that reversibly and rapidly catalyzes reaction->Most CO 2 entering plasma quickly enters RBCs

CO 2 dissolved in_____________and released from Hb also diffuses from____________into_______________

plasma; blood into alveoli

thickened respiratory membrane=

pneumonia and L heart failure (pulmonary edema)->lungs become waterlogged and edematous

Binding of one O 2 causes a shape change in Hb that makes it

progressively easier to bind additional O 2

what happens when Decreased O 2 and increased CO 2 in alveoli results from ventilation being less than perfusion?

pulmonary arterioles constrict and bronchioles dilate

what happens when there is Decreased O 2 and increased CO 2 in alveoli as a result of ventilation being greater than diffusion

pulmonary arterioles dilate and bronchioles constrict