Chapter 8 Flashcards
Aerobic Metabolism
breakdown of molecules such as glucose through a series of reactions that produce energy within the cells in the presence of oxygen.
Glycolysis
glucose crosses the cell membrane, it is broken down into pyruvic acid molecules
adenosine triphosphate (ATP)
energy source that is required by the cell to release more energy and a necessity for cells to carry out certain functions, such as contraction of muscles
Anaerobic Metabolism
the breakdown of molecules in the cells without the presence of oxygen
If the acid accumulates, it produces an acidic environment that may disturb its function and stability. High acid levels inactivate enzyme function, disrupt cell membranes, and ultimately lead to cell death.
Perfusion
described as the delivery of oxygen, glucose, and other substances to the cells and the elimination of waste products from the cells.
Components of Perfusion
Composition of ambient air
Patent airway
Mechanics of ventilation
Regulation of ventilation
Ventilation/perfusion ratio
Transport of oxygen and carbon dioxide by the blood
Blood volume
Pump function of the myocardium
Systemic vascular resistance
Microcirculation
Blood pressure
composition of ambient air
78 percent nitrogen,
21 percent oxygen,
0.9 percent argon
0.03 percent carbon dioxide.
passage of air to lung order
Trachea, Carina, Bronchi, Bronchioles, Alveoli
Ventilation
mechanical process that relies on changes in pressure inside the thorax to move air in and out of the lungs.
Boyles law
An increase in pressure (more positive) will decrease the volume of gas.
A decrease in pressure (more negative) will increase the volume of gas.
Inhalation muscles
Primary: diaphragm
Accessory: SCM, Scalenes, Pec Minor
exhalation muscles
Normally passive
Accessory: Abdominal Muscles, internal inercostal muscles
visceral pleura
lining around lung
pleura space
space between lung and thoracic cavity
parietal pleura
lining of thoracic cavity
minute ventilation/volume
amount of air moved in and out of the lungs in one minute
tidal volume x resp rate/min
tidal volume
volume of air in one breath
average adult tidal volume
500 ml
importance in understanding minute volume
A decrease in minute ventilation reduces the amount of air available for gas exchange in the alveoli.
A decrease in minute ventilation can lead to cellular hypoxia.
To ensure adequate ventilation, the patient must have both an adequate tidal volume and an adequate rate of ventilation.
alveolar ventilation
amount of air moved in and out of the alveoli in one minute
(tidal volume - dead air space) x rep rate/min
average volume lost in the dead air space
150ml
key points to consider with alveolar ventilation
The patient may begin to breathe faster to move more air in and out of the thorax; however, that does not mean he is getting more oxygen into his alveoli for gas exchange.
The dead air spaces will fill first regardless of the volume of air breathed in and the amount made available to the alveoli.
To improve gas exchange in the patient with an inadequate tidal volume, you must provide positive pressure ventilation to move more air into the alveoli.
You cannot improve the ventilation or reverse the cellular hypoxia by simply placing a patient with an inadequate tidal volume on oxygen.
Assessing the tidal volume is as important as assessing the ventilatory rate.
Central Chemoreceptors
located near the respiratory center in the medulla. These receptors are most sensitive to carbon dioxide and changes in the pH of the cerebrospinal fluid (CSF)
peripheral chemo receptors
located in the aortic arch and the carotid bodies in the neck. These chemoreceptors are also somewhat sensitive to co2
and pH but are most sensitive to the level of oxygen in the arterial blood
hypercarbic drive
Normally, a person’s rate and depth of breathing are regulated primarily by the amount of carbon dioxide in the blood
hypoxic drive
Hypoxia becomes the stimulus for ventilation in place of hypercarbia
Three type of lung receptors
irritant, j receptors, stretch
Irritant Receptors
found in the airways and are sensitive to irritating gases, aerosols, and particles.
J Receptors
found in the alveoli near the surrounding capillaries and are sensitive to increases in pressure in the capillary. When activated, the J-receptors stimulate rapid, shallow ventilation.
Stretch Receptors
found in the smooth muscle of the airways and measure the size and volume of the lungs. These receptors stimulate a decrease in the rate and volume of ventilation when stretched by high tidal volumes to protect the lungs from over inflating
Respiratory Control Centers
regulate breathing:
dorsal respiratory group (DRG), ventral respiratory group (VRG), pontine respiratory center.
Dorsal Respiratory Group
located posterior to the VRG
relays its sensory information to the VRG to provide further input on depth and rate of respiration.
Ventral Respiratory Group
located in the anterior portion of the medulla
initiating neural impulses that stimulate the external intercostal muscles and the diaphragm, causing them to contract, which results in inhalation.
Pontine Respiratory Center
sends inhibitory impulses to the VRG1
to turn off the inhalation
how much blood per kilogram in an adult?
70ml/kg(2.2lbs)
composition of blood
45 percent cells
55 percent plasma
vasoconstriction
decrease in diameter of vessel
vasodilation
increase in diameter of vessel
Sympathetic stimulation
causes vasoconstriction, which decreases vessel diameter and increases systemic vascular resistance, increases the diastolic blood pressure.
Parasympathetic stimulation
causes vasodilation, which increases vessel diameter and decreases systemic vascular resistance. decreases the diastolic blood pressure.
Baroreceptors
Help regulate pressure in blood vessels
