Chapter 23 - The Respiratory System - Part 4 Flashcards
do red blood cells have mitochondria?
no
since red blood cells do not have mitochondria, how do they produce their ATP?
through glycolysis
BPG (2,3-bisphosphoglycerate) is generated through glycolysis. This compound has a ____ effect on oxygen binding
DIRECT EFFECT
The higher the concentration of BPG, the ____ the release of oxygen by heme molecules
greater
BPG levels ____ when the pH increases and the Bohr effect appears when the pH _____
BPG levels INCREASE when the pH increases and the Bohr effect appears when the pH DECREASES
When plasma pO2 levels are low for an extended period of time, red blood cells will….
generate MORE BPG because the more BPG, the more oxygen that hemoglobin releases
The Red Blood Cells of a developing fetus contain ___ hemoglobin
fetal
fetal hemoglobin is different from adult hemoglobin in that….
it has a higher affinity for oxygen
Name 3 ways in which carbon dioxide is transported in the blood
- converted to a molecule of carbonic acid
- binds to hemoglobin within red blood cells
- dissolves in plasma
How is MOST CO2 transported in the blood?
as carbonic acid (bicarbonate ions) roughly 70%
When carbon binds to hemoglobin (to exposed amino groups) what is the name of the compound that results?
carbaminohemoglobin
Does plasma become saturated with carbon dioxide quickly or slowly?
quite rapidly
a bicarbonate moves out of the red blood cell in exchange for a…..
chloride ion (chloride shift)
Identify the 3 ways that carbon dioxide is transported in the bloodstream
- as carbonic acid
- dissolved in plasma
- binds to hemoglobin
As you exercise, hemoglobin releases more oxygen to active skeletal muscles than it does when those muscles are at rest. Why?
The combination of increased temperature and lower pH (from heat and acidic waste generated by active skeletal muscles) causes hemoglobin to release more oxygen then when the body is at rest
How would blockage of the trachea affect blood pH?
Blockage of the trachea would interfere with the body’s ability to gain oxygen and eliminate carbon dioxide. Because most carbon dioxide is transported in the blood as bicarbonate ions formed by the dissociation of carbonic acid, an inability to eliminate carbon dioxide would result in an excess of hydrogen ions, which LOWERS BLOOD PH
Equilibrium must exist between peripheral cells and…..
alveolar capillaries
if diffusion rates at the peripheral and alveolar capillaries become unbalanced, name the TWO homeostatic mechanisms involved to restore equilibrium
- changes in blood flow and oxygen delivery that are regulated at the local level
- changes in the depth and rate of respiration under control of the brain’s respiratory receptors
The activities of the respiratory centers of the brain are coordinated with what?
changes in cardiovascular function, such as blood pressure and cardiac output
In a tissue that becomes more active, more O2 is delivered and more CO2 is carried away. the rising pCO2 levels causes what?
the relaxation of smooth muscles in the walls of arterioles and capillaries in the area, causing an increase in blood flow
At the lungs, local factors coordinate which 2 things?
-lung perfusion (blood flow to the alveoli)
-alveolar ventilation (airflow)
As blood flows towards the alveolar capillaries, it is directed towards lobules with a relatively ___ Po2
high
When the PCO2 goes up, bronchioles ___ in diameter
increase
respiratory control has both __ and __ components
voluntary and involuntary
Your brains’ INVOLUNTARY centers regulate the activities of what??
the respiratory muscles. Adjust the frequency and depth of pulmonary ventilation
The VOLUNTARY control of respiration reflects activity in the….
cerebral cortex
What are the “respiratory centers”?
3 pairs of nuclei in the reticular formation of the medulla oblongata and pons
What centers set the pace (rhythm) for respiration?
the “respiratory rhythmicity centers” of the medulla oblangata
-divided into dorsal respiratory group and ventral respiratory group
does the dorsal or ventral respiratory group function in EVERY respiratory cycle, whether quiet or forced?
dorsal respiratory group (has the inspiratory center)
The DRG’s inspiratory center innervates what?
the motor neurons that innervate the external intercostal muscles and the diaphragm
When does the VENTRAL respiratory group function?
only during forced breathing
The VRG has a ___ center
expiratory (and inspiratory)
the expiratory center of the VRG consists of neurons that innervate….
accessory respiratory muscles involved in active exhalation
the inspiratory center of the VRG contains neurons involved in….
maximal inhalation
when the inspiratory neurons are active, what is going on with the expiratory neurons?
the expiratory neurons are inhibited
what is the term for the fact that when inspiratory neurons are active, expiratory neurons are inhibited and vise versa
reciprocal inhibition
to start forced breathing, what event stimulates the neurons of the VRG to activate the accessory muscles involved in inhalation?
increased levels in the activity of the DRG
Name some central nervous system stimulants that increase the respiratory rate by facilitating the respiratory centers
amphetamines, caffeine
the actions of amphetamines, caffeine are opposed by…
central nervous system depressants such as barbiturates or opiates
what centers regulate the depth and rate of respiration?
the apneustic and pneumotaxic centers of the pons
apneustic center does what to our respiratory rate?
sends signals for long, deep breaths. increases the intensity of inhalation. provides continuous stimulation to the DRG
Under normal conditions, after 2 seconds, the apneustic center is inhibited by…
signals from the pneumotaxic center
the pneumotaxic centers ____ the apneustic centers and promote passive or active _____
inhbit, exhalation
in what cases could the inhibitory output of the pneumotaxic centers be cut off?
by a stroke or other damage to the brain stem
results in maximum inhalation for 10-20 seconds at a time with little exhalation and pulmonary ventilation
an increase in pneumotaxic output does what??
quickens the pace of respiration by shortening the duration of inhalation
A DECREASE in pneumotaxic output does what?
slows the respiratory pace but also increases the depth because the apneustic centers are more active
what does SIDS stand for
sudden infant death syndrom
what is thought to be the cause of SIDS
it happens in a time of life when the pacemaker complex and respiratory centers are establishing connections with other portions of the brain. there may be an issue in this interconnection process
The activites of the respiratory centers are modified by sensory info from several sources:
-chemoreceptors are sensitive to changes in blood composition
-baroreceptors in aortic or carotid sinuses are sensitive to changes in blood pressure
-stretch receptors respond to changes in volume of the lungs
-irritants in the nasal cavity, larynx, or bronchial tree
-pain, temp
the respiratory centers are strongly influenced by chemoreceptors from cranial nerves __and __
IX and X
Carotid and aortic body receptors are often called _____ chemoreceptors
peripheral
the carotid bodies and aortic body receptors are stimulated by what?
a decrease in pH or PO2
a rise in CO2 indirectly stimulates these receptors
what are the “central chemoreceptors”
chemoreceptors located on the ventrolateral surface of the medulla oblongata in a region known as the chemosensitive area
the central chemoreceptors respond only to…..
the PCO2 and pH of the CSF
What happens to respiration when chemoreceptors are stimulated?
increase in the depth and rate of respiration
____ levels are mostly responsible for regulating respiratory activity under normal conditions
CO2
What is generated during oxygen consumption?
CO2
When oxygen concentrations are falling rapidly, CO2 levels are usually _____
increasing
If the PO2 remains low for an extended period, what danger does this pose?
this leads the chemoreceptors to adapt to this level of O2. They will oppose any attempts to return the partial pressures to the proper range
what is “hypercapnia”
an increase in the PCO2 of the arterial blood
Can CO2 cross the blood-brain barrier?
yes, quite rapidly
what is the most common cause of hypercapnia??
hypoventilation – respiratory rate is abnormally low and cannot meet the demands for normal O2 delivery CO2 removal so CO2 builds up in the blood
When does hyperventilation exist?
when the rate and depth of respiration EXCEED the demands for O2 delivery and CO2 removal. leads to hypocapnia
if the artierial CO2 drops beyond normal levels, what condition exists?
hypocapni
how do the chemoreceptors respond to hypocapnia?
they decrease their activity and the respiratory rate falls until PCO2 returns to normal and homeostasis is restored
when blood pressure falls, what happens to the respiratory rate?
it increases
what are the “hering-breuer” reflexes?
the inhalation reflex and deflation reflec
what does the inhalation reflex do?
prevents overexpansion of the lungs during forced breathing. As lung volume increase, the DRG is gradually inhibited and the expiratory center of the VRG is stimulated. Inhalation stops as the lungs reach maximal volume and active exhalation begins
the deflation reflex normally only functions during…..
forced breathing
the deflati0on reflex does what?
inhibits the expiratory centers and stimulates the inspiratory centers. the smaller the volume of the lungs, the greater the degree of inhibition
when do the protective reflexes operate and where are they located?
they operate when exposed to toxic vapors etc
they are located in the epithelium of the respiratory tract
give some examples of protective reflexes
sneezing, coughing, laryngeal spasms
Sneezing is triggered by an irritation in…
the nasal cavity wall
coughing is triggered by irritation in..
the larynx, trachea, or bronchi
both sneezing and coughing involved ____
apnea (a period in which respiration is suspended)
explain what is happening during a cough or sneeze
a forceful explosion of air happens to remove the offending stimulus.
the glottis is closed while the lungs are still relatively full. the abdominal and inner intercostal muscles contract suddenly, creating pressures that blast air out of the respiratory passageways when the glottis reopens
Laryngeal spasms result when….
chemical irritants, foreign objects, or fluids enter the area around the glottis
laryngeal spasms do what?
close the airway temporarily
give examples of how the CEREBRAL CORTEX has an indirect effect on the respiratory centers
strong emotions stimulate centers in the hypothalamus
emotional states (sympathetic activation causes bronchodilation and INCREASES respiratory rate)
strenuous exercise
How do pathologists determine if an infant died before delivery or shortly after?
before the 1st breath, the lungs are still completely filled with amniotic fluid so they will sink when placed in water
however, the lungs contain enough air after delivery so even though the lungs are collapsed they will float in water if they were able to take their first breath
What effect does exciting the pneumotaxic centers have on respiration?
inhibits the inspiratory and apneustic centers, which results in shorter, more rapid breaths
Are peripheral chemoreceptors as sensitive to levels of carbon dioxide as they are to levels of oxygen?
peripheral chemoreceptors are more sensitive to carbon dioxide levels than oxygen levels.
Little johnny is angry with his mother, so he tells her that he will hold his breath until he turns blue and dies. should johnny’s mother worry?
johnn’ys mother shouldn’t worry. When johnny holds his breath, blood carbon dioxide levels increase, causing increased stimulation of the inspiratory center and forcing johnny to breathe again
give 3 example of things that reduce the efficacy of the respiratory system in elderly individuals
- With age, elastic tissue deteriorates throughout the body. Reduces the compliance of the lungs and vital capacity
- Chest movements are restricted by arthritic changes
- Some degree of emphysema is normal in individuals over 50
Identify the functional relationship between the respiratory system and all other organ systems
The respiratory system provides oxygen and eliminates carbon dioxide for all body systems
describe the functional relationship between the respiratory system and lymphatic system
the respiratory system provides alveolar phagocytes and respiratory defenses to trap pathogens and protect deeper tissues. tonsils within the lymphatic system protdct against respiratory infection and lymph drainage from the lungs mobilizes defenses to ward off infection
