D11-D12 Flashcards
What is the major difference in the pulmonary system?
it is a low pressure system with little smooth muscle
What is an important characteristic of the pulmonary blood vessels?
the large capillary bed surrounding each alveoli
How long is blood in the capillaries?
about 3/4 of a sec
What is the volume of blood in the pulmonary vessels at any one time?
1 liter
What is the volume of blood in the capillaries?
100 ml
What is the pulmonary capillary pressure?
about 10 mmHg
What is the oncotic pressure of the plasma?
25 mm Hg
What does the pressure gradient in the capillaries favor in terms of movement of fluids?
from alveoli to the capillaries
At what pressure does pulmonary congestion and edema happen?
more than (>25 mmHg)
What disease gives a chronic and progressive rise in pulmonary capillary pressure resulting in a backup in the lungs?
mitral stenosis
What causes pulmonary vessels to constrict?
decrease in PO2
Where is angiotensin I converted to angiotensin II?
The lungs (but comes from the heart)
HyPOventilation increases what and decreases what?
increases arterial PCO2 to make carbonic acid and decreases ph
HyPERventilation increases what and decreases what?
increases ph and decreases pco2
Why is CO2 called a volitile acid?
Because it can be removed by ventilation
What are acids generated by metabolic pathways called and where are they disposed of?
fixed acids and are disposed of by the kidneys
What is associated with respiratory acidosis occur?
hypoventilation (high PCO2 levels)
What is associated with respiratory alkalosis?
hyperventilation (low arterial PCO2 levels)
What causes metabolic acidosis?
increased lactic acid production from exercise or loss of alkali from diarrhea
What causes metabolic alkalosis?
from acid loss that would occur from vomiting
Where are the cell bodies of the motor neurons that innervate the respiratory muscles?
C3-5 (keeps diaphragm alive)
What is the main nerve that makes the diaphragm function?
phrenic nerve
Where does control come from during automatic control of ventilation?
central chemoreceptors in the brainstem and peripheral chemoreceptors
What controls voluntary control of ventilation?
higher centers of the brain
List 3 characteristics of voluntary control.
- enables a person to hold their breath
- located in the cerebral cortex
- sends impulses to respiratory motor neurons through the corticospinal tract
List 3 characteristics of automatic respiration
- main components are in the medulla responsible for automatic respiration
- the pre-botzinger complex makes rhythmic discharges in the phrenic nerve
- associated with the respiratory control pattern generator
What 2 substances do the neurons in the pre-botzinger complex?
substance P
opioids
What does substance P do?
stimulates respiration
What do opioids do to respiration?
inhibit respiration
Where is the pneumotaxic center located?
the pons of the brain stem
What 2 things will the pneumotaxic center do?
- plays role in switching from breathing in to breathing out
- will influence the respiratory components in the medulla
- when damaged, it slows the rate of respiration and increases tidal volume
What increases the level of respiratory neuron activity in the medulla?
a rise in PCO2 or H+ concentration or a decline in PO2
What do chemoreceptors in carotid bodies and aortic bodies respond to?
low levels of PO2 in the arterial blood (only O2 that is dissolved in the plasma)
When do peripheral chemoreceptors respond?
When arterial PO2 is below 60 mm Hg, so they don’t play a role in normal regulation of respiration, only during an emergency.
What is the saturation of Hb?
about 90% with a PO2 of 60 mm Hg
What do central chemoreceptors do?
give typical control for ventilation:
1. alveolar ventilation = PCO2 levels in arterial blood
2. CO2 levels in the blood = CO2 levels in the interstitial fluid
(a)What stimulates H+ levels in the interstitial fluid and in turn, (b)stimulates what?
(a)CO2 levels
(b)central chemoreceptors
What are the arterial PCO2 levels kept at?
40 mmHg (small change can dramatically affect respiration)
What happens when CO2 is inhaled and what does it stimulate?
PCO2 in the blood will increase, stimulating ventilation
What causes depression of the CNS including respiratory center, headaches, confusion, and eventually coma?
when PCO2 of inspired gas is close to the PCO2 of the alveoli, causing difficulty eliminating CO2
How much can blood flow change when exercising?
from 5.5 liters/min to as much as 20-35 liters/min
How much can O2 entering the blood increase during exercise?
from 250 ml/min to as high as 4000 ml/min
What are the 3 factors of “getting into shape”
- how well gas exchange occurs
- heart gets more effective via stroke volume
- increase number and size of mitochondria
What causes oxygen debt?
anaerobic respiration
Why does being in shape require less rest time?
you have more mitochondria to replenish faster by making more O2
What is the driving force of the increased ventilation?
arterial H+ levels due to increased lactic acid
What 3 things do the tissues change during exercise?
- increased temps
- pH changes
- 2,3-BPG levels increase
What is hypoxia?
oxygen deficiency at the tissue level
What are the 4 types of hypoxia?
- hypoxic
- anemic
- stagnant
- histotoxic
What is hypoxic hypoxia?
the PO2 of the arterial blood is reduced (effects of high altitude or disease)
he also mentioned a couple of times that this type of hypoxia can make enough RBC, hemoglobin just can’t get enough O2 to fill it up
What is anemic hypoxia?
low oxygen carrying hemoglobin
What is stagnant hypoxia?
low blood flow to the tissues (not enough blood to get around to all of the tissues)
What is histotoxic hypoxia?
happens because of a toxic agent and cant make use of the oxygen that is being supplied to the tissue cells.
What is the blood oxygen level of hemoglobin in anemia?
7 g/dl
What are the normal oxygen-hemoglobin blood content?
14 g/dl
How much “pure” oxygen causes irritation, distress, congestion and coughing?
80-100% for 8HRS or more
What is hypercapnia?
retention of CO2
What causes symptoms to occur during hypercapnia?
- depression of CNS due to increased H+ levels
How much increase in CO2 is there during a fever?
13% increase for every 1 degree C rise in temp
What is hypocapnia?
Result of hyperventilation
What are the levels of PCO2 and alveolar PO2 during hypocapnia?
from 40 mmHg to as low as 15 mm Hg (PCO2 decrease)
alveolar PO2 levels rise to 120-140 mmHg (PO2 increases)
What are 2 pulmonary diseases?
obstructive and restrictive
What is obstructive disease?
an increase in resistance to airflow to to partial or complete obstruction (hard to get O2 out of the lungs than getting it into the lungs)
What is restrictive disease?
reduced expansion of lungs with decreased total lung capacity (moving air in and out isn’t a problem, just the volume of air is)
What is a measure of lung volumes that measures the force of expiratory volume in one second?
FEV1
What does vital capacity consist of?
tidal volume + inspiratory reserve + expiratory reserve
What is forced spirometry?
compares the lung volumes when trying to move air as fast as possible
What are some examples of restrictive disease?
- pulmonary fibrosis (elastic collagen gets stiff)
- extreme obesity (too much weight for the diaphragm to move)
- neuromuscular disease (damage to phyrenic nerve)
What are some examples of obstructive disease?
bronchial asthma (COPD)
emphysema (messed up air sacs)
