Chapter 22 Flashcards
inhaling
inspiration
exhaling
expiration
relaxed, unconscious, automatic breathing, the way one would breathe when reading a book or listening to lecture without thinking about breathing
quiet respiration
deep or rapid breathing, as in a state of exercise or when singing
forced respiration
what are lungs ventilated by?
pressure gradients by the muscle movements
___ is the primary mover of breathing
diaphragm
where is the ventral respiratory group located?
medulla oblongata
ventilation of the lungs (breathing) or the use of oxygen in cellular metabolism
respiration
breathing, or pulmonary ventilation, consists of repetitive cycle of ___ and ___
inspiration and expiration
what are the principal muscles of respiration?
diaphragm and intercostal muscle
the ___ is the prime mover of respiration; it alone produces about 2/3 of the pulmonary airflow.
diaphragm
what muscles serve as synergist to aid the diaphragm?
internal and external intercostal muscles between the ribs
the primary function of these muscles are to stiffen the thoracic cage during respiration and prevent it from caving inward when the diaphragm depends
internal and external intercostals
other muscles of the chest and abdomen also aid in breathing, especially during forced respiration; thus they are considered ___ ___ of respiration
accessory muscles
energy-saving passive process achieved by the elasticity of the lungs and thoracic cage
normal expiration
Depression of the diaphragm raises abdominal pressure and helps to expel the contents of certain abdominal organs, thus aiding in childbirth, urination, defecation, and vomiting. During these actions, we often consciously or unconsciously employ the ___. This consists of taking a deep breath, holding it by closing the glottis and then contracting the abdominal muscles to raise abdominal pressure and push the organ contents out.
valsalva maneuver
2 reasons for this dependence on the brain for breathing:
(1) skeletal muscles, unlike cardiac muscle cannot contracts without nervous stimulation
(2) breathing involves the well-orchestrated action of multiple muscles and thus requires a central coordinating mechanism
breathing is controlled at 2 levels of the brain
1) cerebral and conscious; enabling us to inhale and exhale at will
2) unconscious and automatic
the primary generator of the respiratory rhythm
ventral respiratory group (VRG)
The ventral respiratory group (VRG) is an elongated neural network in the medulla with 2 commingled webs of neurons ____ and ____ - each forming a reverberating neural circuit
inspiratory (I) neurons & expiratory (E) neurons
a web of neurons that extends for much of the length of the medulla between the VRG and the central canal of the brainstem
dorsal respiratory group (DRG)
a web of neurons that extends for much of the length of the medulla between the VRG and the central canal of the brainstem
dorsal respiratory group (DRG)
receives input from higher brain centers including the hypothalamus, limbic systems, and cerebral cortex, and issues output to both the DRG and VRG
pontine respiratory group (PRG)
this respiratory group hastens or delays the transition from inspiration to expiration, making each breath shorter and shallower, or longer and deepens
pontine respiratory group (PRG)
this respiratory group adapts breathing to special circumstances such as sleep, exercise, vocalization, and emotional responses
pontine respiratory group (PRG)
brainstem neurons that respond especially to changes in the pH of the cerebrospinal fluid
central chemoreceptors
these receptors are located in the carotid and aortic bodies of the larger arteries above the heart
peripheral chemoreceptors
these receptors respond to O2 and CO2 content of the blood but most of all pH
peripheral chemoreceptors
these receptors are found in the smooth muscle of the bronchi and bronchioles and in the visceral pleura
stretch receptors
these receptors respond to inflation of the lungs and signal the DRG by way of the vagus nerves
stretch receptors
excessive inflation triggers the ____, a protective somatic reflex that strongly inhibits the I neurons and stops inspiration
inflation (Hering-Breuer) reflex
these receptors have nerve endings amid the epithelial cells of the airway
irritant receptors
these receptors transmit signals by way of the vagus nerves to the DRG and the DRG returns signals to the respiratory and bronchial muscles, resulting in such protective reflexes as bronchocontriction, shallower breathing, breath-holding or coughing
irritant receptors
the pressure that drives inspiration; the wi=eight of air above us
atmospheric (barometric) pressure
at a constant temperature, the pressure of a given quantity of gas is inversely proportional to its volume.
Boyle’s law
if the lungs contain a quantity of gas and lung volume increases, their internal pressure or their _____ falls. Conversely, if lung volume decreases, it also rises.
intrapulmonary pressure
respiratory airflow is driven by a difference between what?
surrounding (ambient) atmospheric pressure and pressures in the chest
what happens when the thoracic cage expands? why don’t the lungs remain the same size and simply occupy less space in the chest?
Consider the 2 layers of the pleura: the parietal pleura lining the rib cage and the visceral pleura on the lung surface
they are a
