Exam 3 Flashcards
2 distinct circuits of the cardiovascular system
pulmonary and systemic
Pulmonary Circulation
carries deoxygenated from the right ventricle of the heart to the lungs through the pulmonary artery and oxygenated blood from the lungs to the left atrium of the heart by the pulmonary vein
What artery and vein are utilized to move oxygenated and deoxygenated blood through the pulmonary circuit?
- deoxygenated blood = pulmonary artery
- oxygenated blood = pulmonary vein
Systemic Circulation
carries oxygenated blood from the left ventricle of the heart to the rest of the body through the aorta and carried deoxygenated blood from the body to the right atrium of the heart by the vena cava
What artery and vein are utilized to move oxygenated and deoxygenated blood in the systemic circuit?
- deoxygenated blood = vena cava
- oxygenated blood = aorta
define oxygenated blood
increased oxygen (less carbon dioxide)
define deoxygenated blood
more carbon dioxide, less oxygen
where is the highest blood pressure?
during systemic circulation when the heart pushes oxygenated blood from the heart through the aorta to the rest of the body
where is the lowest blood pressure
during systemic circulation when blood goes from the body and is brought back to the heart (need valves and skeletal muscles to perform this)
pulmonary circulation: source
right ventricle
pulmonary circulation: arteries
pulmonary arteries
pulmonary circulation: O2 content of arteries
low
pulmonary circulation: veins
pulmonary veins
pulmonary circulation: O2 content of veins
high
pulmonary circulation: termination
left atrium
systemic circulation: source
left ventricle
systemic circulation: arteries
aorta and branches
systemic circulation: O2 content of arteries
high
systemic circulation: veins
systemicveins that lead to the superior and inferior vena cava
systemic circulation: O2 content of veins
low
systemic circulation: termination
right atrium
direction of blood flow (direction of vessels they move through)
from heart to artery to arteriole to capillary to venule to vein and back to the heart
systole
phase of contraction
diastole
phase of relaxing
why does the heart need diastole?
the heart needs to relax so it can fill with blood
define the cardiac cycle
the repeating pattern of systole (contracting) and diastole (relaxing) of the heart is referred to as the cardiac cycle
does the pulmonary or systemic circulation have a higher blood pressure overall?
systemic
(need to push blood throughout the entire body)
in what vessels does the blood pressure profoundly drop?
capillaries
larger animals have a _______ heart rate
lower
young animals have a _______ heart rate
higher
nutrients provided to blood includes:
- O2
- glucose
- H2O
- AA
waste in blood includes:
- CO2
- H2O
- waste molecules
osmotic pressure
large molecules in blood (that often cannot leave the vessel) will pull things back into the vessel
average human heart rate
75 contractions per minute
how much blood does the ventricle eject on average?
70 ml
the pericardium
the heart is separated from other structures / organs in the thoracic cavity by a covering called the pericardium
what is the function of the pericardium
the membrane separates the structures and allows them to slip and slide to prevent friction and damage
what does the pericardium cover?
surrounds the heart and roots of major vessels closest to the heart
2 distinct sublayers of the pericardium
- fibrous pericardium
- serous pericardium
fibrous pericardium
outer layer
serous pericardium
inner layer
2 distinct sublayers of serous pericardium
- parietal pericardium
- inner visceral pericardium (epicardium)
epicardium
makes up the heart wall
pericardial cavity
the middle layer of the serous pericardium, it is filled with lubricating serous fluid
three layers of the heart wall
- epicardium
- myocardium
- endocardium
epicardium (inner visceral pericardium)
the outer surface of the myocardium, also known as the heart wall
myocardium
- cardiac muscle
- makes contact with blood
- lines atria and ventricles
endocardium
- inner surface of the myocardium
- lines the chambers of the heart and heart valves
- simple squamous epithelium
septa
divides the heart into chambers, a physical extension of the myocardium lined with endocardium
atrias are separated by the _____________ septum
interatrial
ventricles are separated by the ___________ septum
interventricular
between the atria and ventricles is the ___________ septum
atrioventricular
4 heart chambers
- right atria
- left atria
- right ventricle
- left ventricle
which heart chambers carry deoxygenated blood?
- right atria
- right ventricle
which heart chambers carry oxygenated blood?
- left atria
- left ventricle
4 valves of the heart
- mitral / bicuspid valve
- tricuspid valve
- pulmonary valve
- aortic valve
atrioventricular valves
- mitral valve
- tricuspid valve
semi-lunar valves
- pulmonary valve
- aortic valve
main function of heart valves
to prevent back flow of blood during the cardiac cycle
what causes the heart valves to open and close?
pressure
semilunar valves are open during _______
systilly
why do semilunar valves open?
ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves forcing them open
semilunar valves are closed during _______
diastilly
why do semilunar valves close?
ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cups of the valves and forcing them down
what is the second heart sound?
semilunar (aoritc and pulmonary) valves close
atrioventricular valves are angled to allow blood flow from the ______ to the ________, but to immediately close at ventricular contraction
atria to the ventricles
the flaps of atrioventricular (mitral and tricuspid) valves are connected by ________ _________
chordae tendinae
chord tendinae are connected to __________ _________
papillary muscle
why is the muscle in the left ventricle is thicker than the right ventricle?
needs to be strong enough to push the blood throughout the entire body
which valves are open or closed during diastole?
- tricuspid and mitral valve = open
- pulmonary and aortic valve = closed
which valves are open or closed during systole?
- tricuspid and mitral valve = closed
- pulmonary and aortic valve = open
diastole
muscles relax and blood flows into the ventricle
systole
blood contracts and blood flows into the arteries
where does blood come from to get to the superior vena cava?
head, neck, upper limbs, chest
where does blood come from to get to the inferior vena cava?
trunk, viscera, lower limbs
how many flaps does the tricuspid valve have?
3
how many flaps does the mitral valve have?
2
where is the tricuspid valve in the heart?
right ventricle
artery
vessel where blood is moved away from the heart
where is the mitral valve located?
between the left atrium and left ventricle
what is the largest artery?
aorta
“lub” sound
the mitral and tricuspid valve closing
“dub” sound
the aortic and pulmonary valve closing
ECG: P wave
depolarization
ECG: QRS wave
action potential through the ventricle
ECG: T wave
repolarization
2 types of cardiac muscle cells
- myocardial contractile cells (~99%)
- myocardial conducting cells (~1%)
myocardial contractile cells
(function)
can undergo action potentials, responsible for contractions that pump blood to the body
myocardial conducting cells
initiates and propogates the action potential through the heart and can relay them through contractile cells
how are myocardial contractile cells connected?
by intercalated disks
How is DHRP used in cardiac cells?
a switch that is not directly related to RYR but allows Ca voltage gated channels to open
ways cardiac muscles have an influx of Ca
- Ca from the ECF via t-tubules
- sarcoplasmic reticulum
when does the sarcoplasmic reticulum open?
an action potential comes down through t-tubules, DHRP allows Ca voltage gated channels to open, the influx of Ca from ECF stimulates the sarcoplasmic reticulum
another name for the sinoatrial node
the pacemaker
sinoatrial node
group of specialized cardiac muscle cells located in the wall of the right atrium that has the ability to spontaneously produce and action potential
atrioventricular node
coordinates contractions between the atria and ventricles
in the heart, what node has the highest rate of depolarization?
sinoatrial node
action potential of the sinoatrial node
(ions)
- slow influx of Na+
- rapid influx of Ca2+
- efflux of K+
an action potential in the sinoatrial node is produced with ____-type Ca2+ channels open at threshold
L-type Ca2+
HCN Channels (full name)
hyperpolarization - activated cyclic Channels (or funny channels)
HCN Channels function
- Na+ channels
- activated by hyperpolarization
why are HCN Channels important?
they never allow for a resting membrane potential (pacemaker potential), auto rhythmic
2 types of Ca Channels
- transient (t-type) channels
- long lasting (l-type) channels
transient (t-type) channels
- transient = opening is less regulated
- open during pacemaker potential
long lasting (l-type) channels
- open at threshold
action potential in cardiac muscle: rising phase
- depolarization and initial repolarization
- Na+ channels = open (fast)
- K+ channel = open at peak and immediately close
action potential in cardiac muscle: plateau phase
- Ca2+ channels = open (L-type, long lasting)
- K + channels = closed (Ca inhibits K+ channels)
action potential in cardiac muscle: falling phase
- Ca2+ channels close first
- K+ channels open second
why is there a long refractory period in the contraction of the heart?
prevents summation and tetanus and allows the heart to fill with blood
what is the goal of the circulatory system?
get blood to the entire body
every vessel has a _________ (where the blood flows through)
lumen
arteries have a smaller ________ than veins
lumen
veins and venules are ______ than arteries and lumens are _______
thinner, larger
the 3 layers of vessels
- tunica externa
- tunica media
- tunica interna
tunica externa
- outside layer
- protection, collagen rich layer, blood circulation regulation
tunica media
- middle layer
- smooth muscle
tunica interna
- inside layer
- smooth layer to decrease friction
- contact with blood
- endothelium
in the artery, the tunica media is __________, has a ________ endothelium, and a ________ and round lumen
thicker, wavy, smaller
artery
moving blood away from the heart
veins
move blood toward the heart
in veins, the tunica media is ______, has a ________ endothelium, and a _______ and flat lumen
thinner, smooth, larger
3 types of arteries
- elastic artery
- muscular artery
- arteriole
elastic arteries
(structure)
a large tunica media with lots of elastic fibers (allows for stretch and relaxation)
muscular arteries
structure
tunica media contains fewer elastic fibers and more smooth muscle compared to elastic arteries
muscular arteries function
allows for controlled contraction to different parts of the body based on regional need
as the muscular arteries get smaller:
- number of layers of smooth muscle decreases
- internal and external elastic laminae become less prominent
arterioles are closest to the ___________
capillaries
arterioles
tunica media only has 1-2 layers of smooth muscle cells with no elastic fibers
arterioles generate the “_________________” that reduces blood pressure at the periphery and thereby protects the capillaries and venules
peripheral resistance
capillaries main goal
gas and nutrient exchange occurs here
capillaires general structure
- endothelium is a single layer of cells
- basement membrane
- few pericytes
- connective tissues
why do capillaries have fewer layers?
for more easy gas exchange
pericytes
cells that wrap around capillaries and small arterioles and venules, they regulate shape (can constrict and dilate capillaries)
3 types of capillaries
- continuous
- fenestrated
- sinusoidal
most common capillary type
continuous
example of continuous capillary
- finger tips
- prominent in adipose, muscle tissue, and in the brain
continuous capillary structure
have endothelial cells that completely enclose the lumen (have small gaps to let nutrients through)
example of fenestrated capillary
- kidney
- found in renal glomeruli, endocrine glands, intestinal vili, and exocrine pancreas
fenestrated capillary structure
have gaps within / between endothelial cells and a continuous basement membrane
examples of sinusoid capillary
bone marrow
sinusoid capillary structure
large openings in endothelium and basement membrane
sinusoid capillary function
allow passage of the large molecules, including plasma proteins and even cells
venules
tubes of endothelium surrounded by pericytes or 1-2 layers of smooth muscle
function of valves in veins and venules
needed in low pressure valves to promote unidirectional flow of blood toward the heart
retrograde flow
backflow
blood reservoir
- systemic veins can expand to store a high volume of blood
- mobilized when needed (fight or flight)
where are blood reservoirs?
spleen, liver, large abdominal veins, venous plexus beneath the skin
venous return
movement of venous blood toward the heart
various roles of blood
- transportation
- regulation
- protection
blood volume is dependent on ___________
body mass
what does blood transport?
- O2 and CO2
- nutrients
- waste (metabolic, excessive H2O, ions)
what does blood regulate?
- hormones
- heat/temperature
- ph regualtion
what are the protective functions of blood?
- clotting mechanisms to protect against blood loss
- provide immunity
erythrocytes
red blood cells
leukocytes
white blood cells
thrombocytes
platelets
plasma
water + dissolved solutes
(blood is not clotted, blood is spun)
serum
liquid that remains after blood clotting
parts of plasma
(percents)
- 91% water
- 7% blood proteins
- 2% nutrients, hormones, electrolytes
hematocrit
packed cell volume (formed elements)
lymphocytes
help fight viruses and make antibodies
(b-cell and t-cell)
b-cells
a type of lymphocyte, protects the body by producing antibodies
t-cells
a type of lymphocyte, destroy bacteria or cells infected with viruses
neutrophils
kill bacteria, fungi, and foreign debris
monocytes
clean up damaged cells
eosinophils
kills parasites, cancer cells and involved allergic response
basophilis
involved in allergic response
red blood cells lack a _______ and key ___________
nucleus (DNA) and key organelles (ER and mitochondria)
the biconcave shape of ______________ to bond and flow smoothly through the body’s capillaries
red blood cells
average lifespan of red blood cell
- ~120 days
- red blood cells cannot divide or replicate
why are red blood cells red?
due to the iron ions in heme molecules in the protein hemoglobin
main functions of red blood cells
- gas exchange
- regulating blood ph
there is a progressive shortening of diameter from ___________ to _____________
(blood vessels)
arteries to capillaries
when _____________ _____________ are open, blood can flow through a capillary bed
precapillary sphincter
diameter of blood vessels gradually _____________ but surface area correspondingly _____________
decline, increases
blood pressure gradually ___________ as it travels to the capillaries
declines
by the time blood reached the capillary network: vessel diameter ___________, but number of vessels ___________
decreases, increases
why does blood slow down at the capillaries
in order to give time for the exchange of nutrients and gasses
continuous capillary: how does plasma exit?
pores in the walls allow plasma to leak through
continuous capillary: lipid soluble substances exit?
can pass through the wall of the lipid membrane bilayer
continuous capillary: water soluble substances exit?
small water soluble substances pass through the pores (glucose)
continuous capillary: exchangeable proteins exit?
exchangeable proteins are moved across by vesicular transport (steroids and hormones)
continuous capillary: plasma proteins exit?
CANNOT EXIT - cannot pass through the membrane wall
(allows for fluid recovery of capillaries)
interstitial fluid
fluid in the interstitium is derived by filtration and diffusion from the capillaries (same components as plasma but will less proteins)
where is interstitial fluid?
entrapped mainly in small spaces among proteoglycan filaments and collagen fibers
extracellular fluid is made up of
plasma + interstitial fluid
ECF is made up of ____ interstitial fluid and ___ plasma
80% and 20%
bulk flow
mass movement of fluids (and solutes) into and out of capillary beds requires transport processes that are more efficient than diffusion alone
filtration
fluid moves from an area of higher pressure in a capillary bed to an area of lower pressure in the tissues
reabsorption
fluid moves from high pressure in the tissues to lower pressures in the capillaries
2 processes that occur during bulk flow
- osmotic pressure
- hydrostatic pressure
hydrostatic pressure
exerted against the capillary wall, generated by blood pressure
hydrostatic pressure function
promotes the formation of tissue fluid, creates a net filtration pressure (NFP)
osmotic pressure
exerted against the outer capillary wall, generated by plasma proteins
osmotic pressure function
promotes fluid reabsorption in the circulatory system
filtration occurs from the _________ end and reabsorption from the ________ end
arteriole and venule
if interstitial fluid exceeds the ability of the lymphatics to return it to the circulatory system it results in ________
edema
edema
fluid accumulation in interstitial spaces
more fluid moving (filtering) out of the vessels than reabsorbing back in, this excess fluid is absorbed into the ___________ ___________
lymphatic system
3 functions of the lymphatic system
- transport interstitial fluid or lymph back into the blood
- transports absorbed fat from the small intestine to the blood
- helps provide immunological defenses against pathogens
how does the lymphatic system perform immune surveillance?
if there is an infection, it will go through the lymphatic system and along the system are lymph glands that can sense the infection and send out antibodies to begin to fight the infection
what is the challenge of respiration in terrestrial vertebrates?
they cannot use simple diffusion or surface epithelium to get oxygen to all cells
advantages of terrestrial adaptation?
the main advantage of breathing air is the expanded access to oxygen with constant levels of oxygen at different altitudes
Why is air more suitable for breathing than water?
- viscosity is low
- concentration of O2 is higher in air
- diffusion rates are greater
For animals to go from water to land they need to achieve 3 things:
- compartmentalization to increase the surface that is exposed to the breathing medium (lung, alveoli)
- increased vascularization of the gas-exchanging regions (capillaries)
- a barrier sufficiently thin to facilitate gas diffusion (respiratory membrane)
organs used to breath (in order)
nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar sacs, lungs
why does the left lung have a curve?
there is a space for the heart to fit (making it smaller)
how many lobes do the lungs have?
- left = 2
- right = 3
carina
ridge of cartilage that contains specialized nervous tissue that induces violent coughing if foreign material contacts it
trachea
extends from larynx to lungs, formed by 16-20 stacks of C-shaped hyaline cartilage that are connected by dense connective tissue
cartilage is replaced by _________ _________ cells in bronchioles
smooth muscle
alveolar duct
see the budding of alveoli
alveoli
site of gas exchange
alveolar pores
what alveoli are connected by
function of alveolar pores
- helps maintain equal air pressure throughout the alveoli and lung
- alveoli expand as a unit
lung vasculature
the pulmonary artery branches multiple times as it follows the bronchi and each branch becomes progressively smaller in diameter
respiratory membrane
where the capillary wall meets the alveolar wall, it is a thin barrier for gas exchange
pneumocytes
the surface epithelial cells of the alveoli
three types of alveoli cells (pneumocytes)
- type 1
- type 2
- alveolar macrophages
type 1 alveolar cells
a really long cell so it becomes thin, facilitates gas exchange at the membrane (O2 transport)
type 2 alveolar cells
- interspersed among type 1 cells
- secretes pulmonary surfactant
alveolar macrophages
immune cells (phagocytic cell of immune system)
alveolar fluid
coats the alveoli to prevent desiccation
desiccation
drying out due to exposure of air
why does amount of alveolar fluid need to be regulated?
too much fluid decreases oxygen exchange
source of alveolar fluid
gradient between capillaries and interstitium and alveolar airspace
functions of alveolar fluid
- mediates gas transfer
- protective layer
- solvent for various factors
- immune system
surfactants
a major phospholipid that modulate surface tension by reducing hydrogen bonding in the alveoli
do surfactants eliminate surface tension?
NO, but it reduces it
roles of surfactants
- regulate alveolar size
- prevent too much alveolar fluid accumulation
- participates in innate immune function
how do surfactants regulate alveolar size?
minimizes collapse and when the alveoli stretches surfactants get stretched water tension will pull the alveoli back together
how do the surfactants prevent too much alveolar fluid accumulation?
decreasing surface tension will decrease the amount of water that pulls in from the capillaries
how do surfactants participate in immune function?
they have 2 proteins (SP-A and SP-D) that bind to sugars in the surface of pathogens and facilitate uptake by phagocytes (triggers macrophages)
opsonization
how surfactants participate in an immune process (which uses opsonins to tag foreign pathogens for elimination by phagocytes)
2 sites of gas exchange in the body
- external respiration
- internal tissues
the rate of gas diffusion across membranes is directly related to the _______________________________
partial pressure of gases
external respiration
the lungs / alveolar respiratory membrane
external respiration partial pressure of O2 in the alveoli
104 mmHg
partial pressure of CO2 in the alveoli
40 mmHg
external respiration - partial pressure of O2 in the capillaries
40 mmHg
external respiration partial pressure of CO2 in the capillaries
45-47 mmHg
why and where does O2 diffuse to?
O2 is in the alveoli with a partial pressure of 104 mmHg and will move into the capillary with a partial pressure of 40 mmHg
why does the diffusion of O2 occur so quickly?
due to the difference of pressure
why and where does CO2 diffuse to?
the pressure difference between the capillaries (45-47) and the alveoli pressure (40) moves CO2 from the capillaries to the alveoli, but CO2 is 20 times more soluble
the __________ the pressure difference between the lungs and capillaries, the ___________ to move across a gradient
bigger, easier
why do you have a hard time breathing at a high altitude?
as you increase altitude, the total atmospheric pressure decreases meaning that the pressure of O2 decreases making it more similar to the pressure of the capillaries making it more difficult to diffuse O2 across the membrane
what molecule is used to transport O2?
hemoglobin
how many iron are in hemoglobin?
4
where is hemoglobin?
millions of molecules of hemoglobin in a red blood cell
cooperative binding
as each molecule of O2 is bound, it further facilitates the binding of the next molecule until all 4 heme sites are occupied by oxygen
oxyhemoglobin
formed when O2 binds to hemoglobin, is bright red colored molecule that contributes to the bright red color of oxygenated blood
3 major mechanisms of transporting carbon dioxide
- Co2 is dissolved in blood plasma (7-10%)
- CO2 is transported in the form of bicarbonate (HCO3) which also dissolves in the plasma (70%)
- CO2 is transported by erthrocytes (20%)
how is CO2 transported in the form of bicarbonate which also dissolves in the plasma?
bicarbonate moves into the red blood cell through an anti porter called a chloride shift and then bicarbonate is changed into CO2 and H2O which is them released
Haldane Effect
displacement of CO2 with high O2 (O2 binds to hemoglobin which displaces CO2 releasing it into plasma)
t-state of hemoglobin
low O2 affinity (no O2 bonded)
r-state of hemoglobin
high O2 affinity (lots of O2 bonded)
O2 binding changes the equilibrium between the T and R states favoring the _________________
r-states
internal respiration
gas exchange that occurs in the body tissues
partial pressure of O2 in tissue cells
40 mmHg
partial pressure of O2 in capillary
(internal respiration)
104 mmHg
partial pressure of CO2 in tissue cells
(internal respiration)
45-47 mmHg
internal respiration partial pressure of CO2 in capillary
40 mmHg
in internal respiration where will O2 want to move?
O2 will want to move into the tissue because the partial pressure of the capillary is 104 mmHg so it will want to move toward the tissue cells which have a partial pressure of 40 mmHg
in internal respiration where will CO2 want to move?
CO2 will want to move from the tissue into the capillary because the partial pressure in the tissue is 45-47 mmHg which is higher than the partial pressure in the capillary (40 mmHg)
in body tissues the partial pressure gradients are ______________ of those present at the respiratory membrane of the lungs
opposite
Bohr Effect
displacement of O2 by high H+ ions and CO2
a lower ph ________ oxygen dissociation from hemoglobin
promotes
a higher ph ________ oxygen dissociation from hemoglobin
Inhibits
oxyhemoglobin
O2 is bonded to hemoglobin
carbaminohemoglobin
CO2 is bonded to hemoglobin
reduced hemoglobin
H+ is bonded to hemoglobin
Bohr Effect
H+ can bind to the heme group, so if H+ is elevated there is a decrease in binding with oxygen
where does CO2 bind?
alpha and beta chains
carbamino effect
there is a decrease in affinity for oxygen in the presence of carbon dioxide
why does CO2 change into bicarbonate in the red blood cell?
the red blood cell has an enzyme (carbonic anhydrase) that takes carbon dioxide and water and changes it to carbonic acid which almost immediately turns into a bicarbonate anion and a proton
chloride shift
one chloride goes out of the red blood cell and into the plasma and one bicarbonate is released into the red blood cell
Le Chatelelier’s principle
if stressed is placed on a system at equilibrium, the system will proceed in a direction that will minimize stress
Haldane effect
displacement of CO2 with high O2
what is ph?
the concentration of H+ ions
more H+ = ______ ph
lower (more acidic)
less H+ = ______ ph
higher (more basic)
____________ and _________ in the tissues improve O2 dissociation (unloading) from hemoglobin
- low O2
- low ph (acidic)
why does low O2 in the tissues improve O2 dissociation from hemoglobin?
if there is less O2 in the tissues then there is a lower partial pressure, this means the O2 will want to move into the tissues
where are lungs located?
the thoracic cavity
pleura
cavity around the lungs
pleura fluid
secreted by both pleura layers and acts to lubricate and creates surface tension that helps maintain the position of the lungs against the thoracic wall
is inhalation an active or passive process?
active, the chest cavity must expand using muscles in order to breath
are the lungs passive or active when breathing?
passive, they are connected to the thoracic wall
visceral pleura
layer that is attached to the lungs
parietal pleura
the outer layer that connects to the thoracic wall, the diaphragm, and the mediastinum (other structures within the thorax)
intraalveolar pressure
760 mmHg
intralpleural pressure
750 mmHg
what attaches the lungs to the pleura?
pleurafluid, the negative pressure in the pleura “attaches” lungs to the chest
purpose of the pleural membranes
- fluid acts as a lubricant to prevent friction during respiration
- acts as an airtight vacuum due to negative pressure
- keeps lungs inflated and attached to the thoracic wall and diaphragm
inspiration
active contraction of skeletal muscle
expiration
involves muscle relaxation (except during forced expiration)
what causes passive expiration?
elastic recoil of the lungs and chest cage
what 2 muscle groups are used during normal inspiration? (contract with every inspiration)
- diaphragm
- external intercostal muscles (between ribs)
what are the accessory muscles of inspiration that contract only during forceful inspiration?
- sternocleidomastoid
- scalenus
(can feel them in your throat)
muscles involves in active expiration? (contract only during forced expiration)
- internal intercostal muscles
- abdominal muscles
left and right phrenic nerves
carries neural impulses from the respiratory center travel to the diaphragm
what do the cervical, thoracic, and lumbar motor neurons stimulate?
the external intercostal muscles
dorsal respiratory group (DRG)
pacemaker activity, sends efferent signals to maintain constant breathing rhythm by stimulating the diaphragm and intercostal muscles to contract during inspiration
what happens with the dorsal respiratory group pauses?
relaxation of the diaphragm and intercostal muscles creating expiration
what is the dorsal respiratory group influenced by?
by afferent inputs from stretch receptors and chemoreceptors
ventral respiratory group (VRG)
force regulation that becomes active during exercise or stress, containing neurons for both inspiration and expiration, stimulating accessory muscles
where is the dorsal respiratory group, ventral respiratory group, and pre-bontzinger complex located?
the medullary respiratory center (the medulla)
pre-bontzinger
pacemaker neurons that spontaneously depolarize, initiate action potentials and depolarize in a rhythmic fashion
what is the main way in which basal respiratory rate is established?
pre-bontzinger
signals from the pre-bontzinger are relayed to the __________ which transmits them to the inspiratory motor neurons
dorsal respiratory group (DRG)
pontine respiratory groups
- pneumotaxic center
- apneustic center
where are the pneumotaxic and apneustic centers found int he brain?
pons
pneumotaxic center
responsible for the rate of breathing
apneustic center
duration of inspiration
what part of the respiratory group does the pneumotaxic and apneustic centers regulate?
dorsal respiratory group
major sensory inputs that stimulate respiratory centers
- CO2
- H+ ions
minor sensory inputs that stimulate respiratory centers
a high demand for O2
where is the central chemoreceptor located?
in the medulla
central chemoreceptors
monitor CO2
what does the central chemoreceptor do if CO2 is elevated?
respiratory centers are stimulated to increase respiration in order to expel more CO2
how is the central chemoreceptor able to monitor CO2?
CO2 is able to enter the cerebrospinal fluid from the blood, it is then made into bicarbonate and H+, the H+ interacts with the central chemoreceptor to monitor CO2
where is the peripheral chemoreceptor located?
in the carotid arteries and aortic arch
peripheral chemoreceptors
increase afferent signals to the respiratory centers in response to decreases in ph and O2
how are peripheral chemoreceptors stimulated?
by an increase in CO2 partial pressure, but to a lesser extent than central chemoreceptors
what would maximally stimulate the peripheral chemoreceptors?
low ph, high CO2, low O2
