Quiz #6 Flashcards
What are some functions of blood?
transportation of gases, nutrients, hormones, waste
regulate pH and ion composition
restrict fluid loss at injured sites
offer defence against toxins and pathogens
stabilize body temperature
What are the major components of whole blood?
plasma
- 55% of blood
- 90% water, rest is various ions, gases, vitamins, organic molecules
buffy coat
- where you find WBCs (true cells) and platelets
erythrocytes
- RBCs (non-true cells)
What are true cells?
cells with a nucleus and other key organelles
What is plasma?
straw-coloured, sticky fluid. made of over 100 dissolved solutes
mostly electrolytes but proteins by weight
What are red blood cells?
biconcave, large surface area, anucleate, mostly hemoglobin, flexible to deform while passing through small capillaries
picks up O2 in the lungs and releases to tissue
also transports some CO2 from tissue back to lungs
What is hemoglobin?
made of 4 polypeptide chains with 4 heme groups that have an affinity for oxygen
1 polypeptide can carry 1 O2, so 1 hemoglobin can carry 4 O2
What is oxyhemoglobin?
hemoglobin when O2 is bound
ruby red
What is deoxyhemoglobin?
hemoglobin when O2 is detached
dark red
What is carbaminohemoglobin?
hemoglobin when CO2 binds
What is erythropoiesis?
RBC formation
RBCs have a finite lifespan so they are constantly being recycled in the spleen/liver, need to be regenerated in the bone marrow
start as a hematopoietic stem cell
How can EPO be dangerous?
in normal conditions the body is stimulated to produce EPO when low RBCs or increased needs for O2
abusing EPO in blood doping/injections can thicken the blood and clog arteries causing hypertension, stroke, heart attack, etc
What is hematocrit?
% of the whole blood that is RBCs
low hematocrit = thin blood
high hematocrit = thick blood
What are leukocytes?
the only true component of blood
enter tissues to protect against bacteria and viruses
motile; can move through tissue via amoeboid motion to follow a chemical trail of attraction (positive chemotaxis)
What are the 2 types of leukocytes?
granulocytes
- have pockets that contain enzymes that are released to act on organisms to cause response
- neutrophils (phagocytotic)
- eosinophils (allergic responses)
- basophils (allergic responses)
agranulocytes
- do not contain granules
- leukocytes (T cells and B cells, adaptive immune system)
- monocytes (phagocytotic)
What is the acronym for remembering the types of leukocytes?
never let monkeys eat bananas
neutrophils leukocytes monocytes eonophils basophils
What is leukocytosis?
increase in WBC in response to infection
can double in just hours
What is positive chemotaxis?
trail of chemical attraction for leukocytes to follow
How are platelets formed? What is their main function?
megakaryocyte presses against special capillary in red marrow, cytoplasmic extensions extend through and rupture off fragments, creating platelets
clot blood and help repair damaged vessel
What are the functions of lymphatics?
produce, maintain, and distribute lymphocytes
maintain normal blood volume
provide alternative transport route for hormones, nutrients, wastes
What is lymphedema?
fluid buildup in tissues when lymphatic tissues don’t work properly
puts tissue at increased risk of infection
How do lymphatic vessels function?
large vessels with one way valves
smooth muscle contracts in waves
lymph is carried to nodes which act as a filter before returning it to veins
What are the main functions of the respiratory system?
supply O2 for cellular respiration and dispose of CO2
regulate blood pH by changing CO2 levels
assists in olfaction and speech
What are the 4+1 processes of the respiratory system?
pulmonary ventilation (breathing) - movement of air in and out of the lungs
external respiration
- exchange of O2/CO2 between lungs and blood
transport
- of O2 and CO2
internal respiration
- exchange of O2 and CO2 between systemic blood vessels and tissues
+ cellular respiration
- cell metabolism and ATP production
What is air taken in through?
either the oral or nasal cavity
normal resting breathing is done through the nose, as ventilatory needs increase (ex. exercise) we recruit the mouth
What is the larynx?
structured rings that guard entrance to windpipe
What is the epiglottis?
cartilage that comes off the larynx to protect the glottis from food/liquid during swallowing
Describe the general structure of the lungs.
3 lobes on the right, 2 on the left (heart takes up space)
alveoli allow for efficient gas exchange
What is the conducting zone of the respiratory tract?
zone that can move air through it (tube)
What is the role of the glottis?
sound generated by expiration of air through it, vibrating vocal folds
What are the functions of the conducting zone?
air passageway
increase air temp to body temp (humidify air)
What do goblet cells do?
secrete mucus
What do ciliated cells do?
move particles towards the mouth (mucus escalator)
What is the function of the respiratory zone?
gas exchange between air and blood via diffusion
What are the structures of the respiratory zone?
respiratory bronchioles
alveolar ducts
alveolar sacs
alveoli
What are alveoli?
site of gas exchange
300 million in the lungs
What are the 2 types of alveolar cells?
type I
- make up wall of alveoli
- single layer of epithelial cells
type II
- secrete surfactant
What components of the chest wall act to protect the lungs?
ribs sternum thoracic vertebrae internal and external intercostals diaphragm
What is the pleura?
membrane lining of lungs and chest wall
pleural sac around each lung
intrapleural space filled with intrapleural fluid
What is the primary force driving pulmonary ventilation?
pressure gradient (high to low)
difference between Palv and Patm
travels via bulk flow
What is inspiration?
when pressure in lungs is less than atmospheric pressure, air flows in
What is expiration?
when pressure in lungs is greater than atmospheric pressure, air flows out
What is atmospheric pressure?
Patm
pressure of the atmosphere
other lung pressures given relative to it
What is intra-alveolar pressure?
Palv
pressure of air in alveoli
varies with phase of respiration
- negative during inspiration
- positive during expiration
What is interpleural pressure?
Pip
pressure inside pleural sac
always negative under normal conditions due to elasticity in lungs and chest wall, and always less than Palv
What prevents the chest wall and lungs from pulling apart?
surface tension of intrapleural fluid
What is transpulmonary pressure?
Palv - Pip
distending pressure across the lung wall
an increase in transpulmonary pressure increases distending pressure across lungs, causes lungs to expand and increase volume
What is Boyles Law?
pressure is inversely related to volume
What are the determinants of intra-alveolar pressure?
quantity of air in alveoli
volume of alveoli
What muscles work during inspiration?
diaphragm
external intercostals
both contract to expand volume of thoracic cavity
What muscles work during expiration?
internal intercostals and abdominal muscles contract during active expiration only
diaphragm and external intercostals relax
Describe the process of inspiration.
neural stimulation of inspiratory muscles to increase thoracic cavity volume
- diaphragm flattens, external intercostals move ribs up and out
outward pull on pleura decreases intrapleural pressure, increasing transpulmonary pressure
alveoli expand, decreasing alveolar pressure
air flows into lungs by bulk flow
Describe the process of expiration.
normally passive
when inspiratory muscles stop contracting, lungs and chest wall recoil to their original positions, decrease volume of thoracic cavity
active expiration uses contraction of expiratory muscles to create a greater and faster decrease in the volume of the thoracic cavity
What are the main factors affecting pulmonary ventilation?
lung compliance
airway resistance
What is lung compliance?
the ease with which lungs can be stretched
larger compliance = easier to inspire = smaller change in transpulmonary pressure needed to bring in a given volume of air
What factors affect lung compliance?
elasticity
- ability to resist stretch
- more elastic = less compliant
surface tension of lungs
- force for alveoli to collapse or resist expansion
- arises due to attractions between water molecules
- greater tension = less compliant
How do we overcome surface tension?
surfactant is secreted from type II cells
- detergent that decreases surface tension within water molecules, increasing lung compliance making inspiration easier
without surfactant, surface tension would cause alveoli to collapse
How does airway resistance affect ventilation?
more resistance = harder to breathe
as airway gets smaller they increase in numbers so overall resistance is low
What factors affect airway resistance?
passive forces
- during respiratory cycle
- ex. changes in transpulmonary pressure
contractile activity of smooth muscle
- bronchoconstriction and bronchodilation
mucus secretion
- irritants can lead to an increase in mucus secretion which increases resistance
Describe the extrinsic control of bronchiole radius.
PNS
- contraction of smooth muscle
- bronchoconstriction
SNS
- relaxation of smooth muscle
- bronchodilation
opposite of cardiac/skeletal muscle due to receptors
- logical - would want larger airway in fight or flight state
epinephrine
- relaxation of smooth muscle
- bronchodilation
Describe the intrinsic control of bronchiole radius.
histamine
- contraction of smooth muscle
- bronchoconstriction
- released during asthma/allergies
CO2
- relaxation of smooth muscle
- bronchodilation
What is TV?
tidal volume
amount of air taken in during inhalation
about 500 mL
- 300 mL entering alveoli, 150 mL remains in conducting pathway (anatomical dead space - VD)
What is the typical respiratory rate? (f)
12-20 breaths/min
What is VE?
minute ventilation/total pulmonary ventilation
number of breaths x volume of each breath
f x TV
What is VA?
alveolar ventilation
number of breaths x (volume - dead space)
f x (TV - VD)
What is IRV?
inspiratory reserve volume
maximum air inspired at the end of a normal inspiration
What is ERV?
expiratory reserve volume
maximum air expired at the end of a normal expiration
What is RV?
residual volume
air left in the lungs after maximal exhalation
What is hyperpnea?
increased respiratory rate/volume due to increased metabolism
What is hyperventilation?
increased respiratory rate/volume without increased metabolism
What is hypoventilation?
decreased respiratory rate/volume
What is dyspnea?
shortness of breath/difficulty breathing
What is apnea?
cessation of breathing
What is IC?
inspiratory capacity
max amount of air that can be inspired at the end of expiration
IC = TV + IRV
What is VC?
vital capacity
maximum amount of air that can be exhaled following a maximum inhalation
VC = TV + IRV + ERV
(or IC + ERV)
What is FRC?
functional residual capacity
amount of air remaining at the end of normal expiration
FRC = RV + ERV
What is TLC?
total lung capacity
volume of air in lungs at the end of a maximum inhalation
TLC = RV + ERV + IRV + TV
(or VC + RV)
(or FRC + IC)
What is FVC?
forced vital capacity
max-volume inhalation followed by exhalation as fast as possible
low FVC indicates restrictive pulmonary disease
What is FEV?
forced expiratory volume
% of FVC that can be exhaled within a certain time frame
What is FEV1?
% of FVC that can be exhaled within 1 seconds
normal = 80%
less indicates obstructive pulmonary disease
What is maximum voluntary ventilation?
breathing as deeply and as quickly as posisble
What happens in the alveoli during breathing?
as ventilation increases, alveolar PO2 increases and PCO2 decreases
vice versa as ventilation decreases
What changes occur to arterial blood levels of O2 and CO2 over time?
remain relatively constant
O2 moves from alveoli to blood at the same rate as it is consumed by cells
CO2 moved from blood to alveoli at the same rate it is produced by cells
What is Dalton’s Law of Partial Pressure?
each gas contributes to the total pressure in proportion to its number of molecules
What is partial pressure?
total pressure x fraction of a gas
What is the rough composition of air?
N2 - 79%
O2 - 20%
CO3 - 0.03%
What is Henrys Law?
finds the molar concentration of a dissolved gas
both gas form and liquid form of a molecule exert the same partial pressures
Is O2 or CO2 more soluble in water?
CO2 is 20x more soluble in water, and since plasma is mostly water, also more soluble in blood
How does gas exchange occur in gas mixtures?
gases diffuse down their own partial pressure gradients high to low pressure
What does gas exchange between alveolar air and blood depend on?
thickness and surface area of respiratory membrane
- fast at lungs as surface area is large and there is a small barrier
solubility and partial pressure of gases
What determines the amount of O2/CO2 exchanged in a vascular bed depend on?
metabolic activity of the tissue
greater rate of metabolism = greater exchange
What factors affect the alveolar PO2 and PCO2?
PO2 and PCO2 of inspired air
minute alveolar ventilation
rates at which respiring tissues use O2 and produce CO2
What is tachypnea?
rapid, shallow breathing
What is hypoxia?
deficiency of oxygen in the tissues
What is hypoxemia?
deficiency of oxygen in the blood
What is hypercapnia?
excess of CO2 in the blood
What is hypocapnia?
deficiency of CO2 in the blood
How soluble is O2 in plasma?
not very
only 1.5% arterial blood O2 is dissolved
other 98.5% is transported by hemoglobin
How does the law of mass action apply to the saturation of hemoglobin?
more oxygen = more binding to Hb
non-linear
What is saturation?
a measure of how much O2 is bound to hemoglobin
How does temperature affect hemoglobins affinity for oxygen?
increasing temperature cause active tissue, increase in O2 unloading in the tissues
How does pH affect hemoglobins affinity for oxygen?
Bohr effect
- lower pH = more O2 unloading
How does the CO2-carbamino effect affect hemoglobins affinity for oxygen?
CO2 reacts with hemoglobin to form carbaminohemoglobin
has lower affinity for O2 than hemoglobin
increased metabolic activity increases CO2, increasing oxygen unloading in active tissue
What are the effects of 2,3-DPG on hemoglobins affinity for oxygen?
produced in RBC in conditions of low O2 (anemia, high altitude)
decreases affinity of Hb for O2, enhancing unloading
How does carbon monoxide affect hemoglobins affinity for oxygen?
Hb has greater affinity for CO than O2
prevents O2 from binding
Where is all the CO2 in the blood?
5-6% dissolved in plasma
5-8% bound to HB
86-90% converted to bicarbonate and transported in plasma
What is carbonic anhydrase?
enzyme that converts CO2 and H2O to carbonic acid
How does the law of mass action relate to CO2?
an increase in CO2 causes an increase in bicarbonate and hydrogen ions
What is the chloride shift?
HCO3- (bicarbonate) enters plasma in exchange for Cl-
What is the Haldane effect?
as CO2 content in blood decreases, PO2 increases
property of hemoglobin - deoxygenation of blood increases its ability to carry CO2
What is involved in the neural control of breathing muscles?
phrenic nerve - diaphragm
intercostal nerves
respiratory centres in the CNS
What part of the brain is in charge of voluntary ventilation?
cerebral cortex
affects respiratory centres and motor neurons controlling respiratory muscles
What is the role of the medulla oblongata in breathing?
sets the pace of respiration
dorsal respiratory group
- inspiratory muscles
- involved in quiet breathing
ventral respiratory group
- inspiratory and expiratory muscles
- involved in forced breathing
What is the role of the pons in breathing?
influence on both inspiratory and expiratory neurons
transition between inspiration and expiration
What are the sensory modifiers of respiratory activities? (5)
chemoreceptors
- sensitive to partial pressures or pH of blood/CSF
- peripheral (carotid and aortic) and central (medulla)
baroreceptors
- sensitive to changes in BP
- in aortic or carotid sinuses
stretch receptors
- respond to changes in lung volume
- ensure lungs don’t overinflate
irritating physical/chemical stimuli
- in nasal cavity, larynx, or bronchial tree
other sensations
- pain, body temp, etc
What levels of arterial PCO2 can be dangerous?
over 90 mmHg = coma
over 180 mmHg = death
How does PO2 influence chemoreceptor sensitivity to PCO2?
decreased PO2 will increase sensitivity to PCO2
What are Hering-Breuer reflexes?
inflation reflex
- stretch receptors in bronchiole smooth muscles stimulates expiratory center to prevent overexpansion
deflation reflex
- inhibits expiratory centers and stimulates inspiratory centers during lung deflation
What is the ventilation-perfusion ratio?
matching of ventilation to perfusion to ensure efficient gas exchange
ventilation = rate of air flow (V) perfusion = rate of blood flow (Q)
VA/Q
What happens if ventilation to certain alveoli decreases?
increased PCO2 and decreased PO2 in blood and air
increased PCO2 in bronchioles = bronchodilation
decreased PO2 in arterioles = vasoconstriction
What happens if perfusion to certain alveoli decreases?
increased PO2 and decreased PCO2 in blood and air
increased PO2 in arterioles = vasodilation
decreased PCO2 in bronchioles = bronchoconstriction
How long can voluntary breathing override involuntary breathing?
until an increase in H+ and PCO2 ions cause involuntary to take over again
breathholding is intolerable at PCO2 of 50 mmHg
What is one strategy to enhance breath holding?
hyperventilating before
cause abnormally low PCO2, start at lower levels so it takes longer to get to intolerable levels
What is acidosis?
blood pH under 7.35
CNS depression
6.8 = death
What is alkolosis?
blood pH over 7.45
CNS over-excitation
8.0 = death
What is normal blood pH?
7.4
How does hemoglobin function as a buffer?
binds or releases H+
deoxyhemoglobin has a greater affinity for H+ (Bohr effect)
How can bicarbonate act as a buffer?
bind to H+ creating H2CO3 which can create CO2 and H2O, also REVERSIBLE
can regulate pH by regulating CO2 levels
What must be maintained to keep a normal arterial pH of 7.4?
the bicarbonate:carbon dioxide ratio must be 20:1
respiratory system regulates CO2, kidneys regulate HCO3-
