Week 8 Flashcards
respiratory system consists of
nose, pharynx, larynx, trachea, bronchi, lungs
bronchi has
- primary, secondary and tertiary
- terminal and respiratory bronchioles
- alveolar ducts
- alveoli
how is cartilage replaced by smooth muscle
branching
alveoli anatomy
small, thin walled sacs that have capillary beds in their walls
site of gas molecule exchange between air and blood
respiratory membrane anatomy
separates the air molecules in the alveoli from blood in the capillaries
- average thickness is 0.6 micrometers
- very thin-optimized for diffusion
- very large surface area
- 70 square meters in normal adult
mechanics of breathing
pulmonary ventilation is the movement of air into and out of the lungs
molecules move from areas of high pressure to areas of low pressure
boyles law
the pressure of a has is inversely proportional to its volume
how does movement of air into and out of the lungs work
results from pressure differences between pulmonary air and the atmospheric air
compliance
the amount of volume change in the lung for a given change in alveolar pressure
inspiration
diaphragm descends and external intercostal muscle contract which increase volume of the thoracic cavity and decreases pressure in the thoracic cavity
expiration
passive process at rest
- diaphragm and external intercostal muscles relax thus decreasing the volume of thoracic cavity
- pressure in thoracic cavity increases above atmospheric pressure and air molecules move out of the lung following the pressure gradient
mouth breathing in exercise
air that enters through the nose or mouth is quickly saturated with water vapour and warmed to body temperature, 37 degrees, even under conditions when very cold air is inspired
tidal volume
volume of gas inspired or expired with each breath at rest or during any stated acidity
expiatory reserve volume
maximal volume that can be exhaled from the resting end expiatory position
inspirotiry capacity
maximal volume of gas that can be inspired from the resting and expiatory position
vital capacity
greatest volume of gas that can be expelled by voluntary effort after maximal inspiration
sum of the inspritory capacity and the expiatory reserve volume
residual volume
the volume of gas remaining in the lungs after forced expiration
functional residual capacity
volume of gas remaining in the lungs at the end of a quiet exhalation
total lung capacity
vital capacity plus residual volume
forced vital capacity manoeuver
one in which the subject is instructed to expire as hard and as fast as possible for four seconds
forced expiatory reserve volume in one second
the volume of air expired during the first one second of a forced vital capacity manoeuvre
alveolar ventilation
the volume of air that reaches the alveoli per minute
the only air that participates in gas exchange with the blood
anatomical dead space is subtracted from tidal volume to obtain Va
why do lung volumes and capacities decrease when a person lies down and increase when standing?
- abdominal contents push up against diaphragm
- there is an increase in intrapulmonary blood volume in the horizontal piston which decreases the space available for pulmonary air
problems with pulmonary function norms
don’t consider the size of the subject, particularly chest size
would be better to use sitting height rather than standing
tests must be interpreted in relation to a patients medical history, occupational history, smoking habits and a chest x ray
ventilation during incremental exercise
minute ventilation increases linearly with increasing exercise intensity until approximately 50-60% of VO2 max in untrained subjects and 75-80% of VO2 max in endurance athletes
ventilatory threshold
the point at which minute ventilation increases disproportionately with oxygen consumption during faded exercise
obstructive respiratory disorders
blockage or narrowing of the airways causing an increased airway resistance
- more difficult to move air in and out
- blockage due to inflammation and edema, smooth muscle constriction or bronchiolar secretion
- asthma, bronchitis, emphysema
restrictive respiratory disorders
damage to the lung tissue
- loss of elasticity and compliance limiting expansion of the lung
- pulmonary fibros, pneumonia
circulatory system composed of
heart, blood vessels, lungs
function os circulatory system
transport essential materials throughout body to cels
- oxygen
- white blood cells
- nutrients
- signalling molecules
- collects waste materials from body metabolic activity
pulmonary circuit
blood vessels going to and from the lungs
systemic circuit
blood vessels going to and from the rest of the tissues of the body
heart
4 chamber muscular pump that propels blood through blood vessles
- upper chambers: atria
lower chambers: ventricles
right ventricle
pumps blood through the pulmonary circuit
left ventricle
pumps blood through the systemic circuit
electrical conduction in myocardial cells
auto rhythmic cells spontaneously fire action potentials
depolarization then spreads through gap junctions
action potentials in contractile cells
electrocardiography
record the wave of depolarization as it passes across the heart using electrodes on the surface of the body
arrhythmia
an irregularity in the rhythm of the heartbeat
common arrhythmias
tachycardia: HR is faster than normal
Bradycardia: HR is slower than normal
Fibrillation: electrocardiogram is disorganized
atrial fibrillation: heart still functions as a pump
ventricular fibrillation: heart does not function as an effect pump
what arteries is the heart muscle supplied with
originate from the aorta just above the aortic valve, left coronary artery, right coronary artery
artery function and composition
receive and propel high pressure blood flow
muscular highly elastic
arteriole function and composition
vary resistance to blood flow
muscular well innervated
capillary function and composition
exchange of materials
thin walled highly permeable
venule function and composition
collect blood from capillaries
thin walled some fibrous tissue
vein function and composition
easily collapse or expand to maintain venous return
fairly muscular highly distensible
skeletal muscle pump
active muscles squeeze the veins and push the blood towards the heart
respiratory pump
decreased pressure in thoracic cavity during inspiration makes it easier for blood to return from lower portions of body via inferior vena cava- thoracic cavity then right atrium of the heart
blood is composed of
red blood cells
white blood cells
platelets
suspended in liquid plasma which makes up to 50-60% of blood by volume
hemoglobin
transports oxygen and carbon dioxide
consists of 4 sub units each of which contain a molecule of iron
reversibly binds with oxygen
rate of diffusion is increased by
higher concentration gradient
shorter diffusion distance
higher temperature
greater surface area
gas exchange
alveolar capillary membrane in the lung: net diffusion of O2 from alveoli to blood
net diffusion of CO2 from blood to alveoli
tissue capillary membrane in tissues: net diffusion of O2 from blood to tissue, net diffusion of CO2 from tissue to blood
functional residual capacity
serves as a damper so that each incoming breath of air has only a small effect on the composition of the alveolar air
partial pressure of gases in the alveoli remains relatively stable
henrys law
amount of gas that dissolves in a fluid is a function of two factors; 1. the pressure of the gas above the fluid, which is given by the gas concentration times the barometric pressure
2. the solubility coefficient of the gas- CO2 is 20.3 times more soluble in water than O2.
lung diffusing capacity
the volume of oxygen that crosses the alveolar-capillary membrane per minute per mmhg between the alveolar air and pulmonary capillary blood
