Circulatory System Flashcards
- network of cylindrical vessels that emerge from a pump
- moves nutrients, hormones, oxygen, and other gases to the body’s organs, muscles, and tissue for energy, growth, and repair
circulatory system
what is the circulatory system
- network of cylindrical vessels that emerge from a pump
- moves nutrients, hormones, oxygen, and other gases to the body’s organs, muscles, and tissue for energy, growth, and repair
what is the function of the circulatory system in humans
- transport blood, oxygen, and nutrients to the body
- guards against pathogen invasion
- regulates body temperature
- buffers body pH
- maintain osmotic pressure
- clots prevent blood or fluid loss
Main parts of the human circulatory system
- heart
- blood vessels
- blood
- works as a pump to move the blood around the body
- has four chambers - two atria and two ventricles
heart
four chambers of the heart
two atria
two ventricles
takes in blood carrying carbon dioxide
right atrium
where is deoxygenated blood squeezed down into
right ventricle and to the lungs
where oxygen replaces carbon dioxide
lungs
where oxygenated blood enters
left atrium
where does the blood go after the left venticle pumps it
throughout the body
tissue layers of the heart wall
- epicardium
- myocardium
- endocardium
- outer layer of the wall of the heart
- formed by visceral layer of the serous pericardium
epicardium
what is epicardium made out of
visceral layer of the serous pericardium
- muscular middle layer of the wall of the heart
- has excitable tissue and the conducting system
myocardium
what does the myocardium have
- excitable tissue
- conducting system
- composed of simple squamous epithelial cells which form the inner lining of the heart chambers
- connects to blood vessels that supply the heart muscle and contributes to the regulation of heart contraction
endocardium
between the endocardium and myocardium and contains the impulse-conducting system
subendocardium
Cell Composition of the Heart
- myocardial contractile cells
- myocardial conducting cells
- constitute the bulk (99 percent) of the cells in the atria and ventricles
- conduct impulses and are responsible for contractions that pump blood through the body
myocardial contractile cells / cardiomyocytes (CMs)
- initiate and propagate the action potential (the electrical impulse) that travels throughout the heart
- triggers the contractions that propel the blood
myocardial conducting cells
different myocardial conducting cells
- sinoatrial (SA) node cells
- atrioventricular (AV) node cells
- Purkinje fibers
- located in the superior and posterior walls of the right atrium close to the opening of the superior vena cava
- has the highest inherent rate of depolarization and therefore referred to as the pacemaker of the heart.
Sinoatrial (SA) node cells
- responsible for transmitting impulses that originate in the sinoatrial (SA) node to the ventricles of the heart
- has the ability to slightly delay electrical signals, thus coordinating the contraction firstly of the atria and secondly of the ventricles.
Atrioventricular (AV) node cells
- branches of specialized nerve cells that send electrical signals very quickly to your right and left heart ventricles
- are in the subendocardial surface of your ventricle walls
Purkinje fibers
tubes or channels that carry blood throughout our body
blood vessels
three types of blood vessels
- veins
- arteries
- capillaries
has the thickest wall of the three, allowing it to withstand high pressure created by the heart
Arteries
has the thinnest wall to allow substances such as oxygen and sugar to pass through its wall - into or out of the blood
capillary
- less muscular and stretchy so blood moves through it with low pressure
- also has special valve that helps blood go only one way
vein
artery
carries blood away from the heart
(thickest)
capillary
assists in the exchange of substances between the blood and tissues
(thinnest)
vein
carries blood back towards the heart
(less muscular and stretchy)
special fluid primarily contained within the blood vessels
blood
four main components of the blood
- red blood cells
- white blood cells
- platelets
- plasma
types of circulatory system
- open
- closed
blood is not enclosed in the blood vessels but is pumped into a cavity called a hemocoel
open circulatory system
blood is contained inside blood vessels, circulating in one direction
closed circulatory system
Circuits of the circulatory system
- pulmonary circuit
- systemic circuit
- moves blood betwen the heart and the lungs
- transports deoxygenated blood to the lungs to absorb oxygen and release carbon dioxide
- oxygenated blood then flows back to the heart
pulmonary circuit
- moves blood between the heart and the rest of the body
- sends oxygenated blood out to cells and returns deoxygenated blood to the heart
systemic circuit
Conduction System of the Heart
- sinoatrial (SA) node
- atrioventricular (AV) node
- bundle of HIS
- bundle branches
- Purkinje fibers
collection of specialized cells (pacemaker cells)
sinoatrial (SA) node
- located within the atriventricular septum
- delays the signal from the sinoatrial (SA) node to ensure that the atria have emptied the blood into the ventricles before pumping
atrioventricular (AV) node
continuation of the specialized tissue of the AV node
bundle of HIS
offshoots of the bundle of His that carry electrical impulses from the bundle of His to the Purkinje fibers, which causes the ventricles to contract.
bundle branches
- sub-endocardial plexus of conduction cells
- abundant with glycogen and have extensive gap junctions.
- transmit signal to the ventricles causing them to contract
Purkinje fibres
Sequence of electrical events
- action potential generated at sinoatrial (SA) node
- excitation signal spreads and cause atria to contract
- excitation signal reaches atrioventricular (AV) node where it is delayed
- signal reaches bundle of His, bundle brances and down to the Purkinje fibers
- wave impulses are spread along the ventricles causing them to contract
two phases of the cardiac cycle
- systole (contraction phase)
- diastole (relaxtion phase)
occurs when the heart contracts to pump blood out
systole
occurs when the heart relaxes after contraction
diastole
- atial depolarization/contraction
- remaining blood is pushed into the ventricles
atrial systole
ejects blood into the outflow tract because there is sufficient blood pressure to open the outflow valve
ventricular systole
when does the cariac cycle end
when ventricles relax (ventricular diastole)
two main parts during ventricular systole
- isovolumetric contraction
- ejection
- ventricles begin to contract and pressure inside the chambers increase
- all valves are closed which makes the venticular volume of the blood to remain constant
isovolumetric contraction
- ventricular pressure exceeds the aoritc and pulmonary artery pressures, opening the semilunar valves
- there is forceful ejection of blood from the ventricles into the aorta and pulmonary artery
ejection
- located at the connections between the pulmonary artery and the right ventricle, and the aorta and the left ventricle
- valves allow blood to be pumped forward into the arteries, but prevent backflow of blood from the arteries into the ventricles
semilunar valves
- located on the left side of the heart, between the left atrium and the left ventricle
- has two leaflets that allow blood to flow from the lungs to the heart
mitral valve
located on the right side of the heart, between the right atrium and the right ventricle
tricuspid valve
two parts of diastole
- isovolumetric relaxation
- passive filling
- begins the ventricular relaxation where there is a decrese in pressure
- ventricular volume of the blood remains constant because all the valves are closed again
isovolumetric relaxation
- opening of the AV valves because of the decrease in ventricular pressure below atrial pressure
- the blood flow passively from the atria into the ventricles
passive filling
all four valves are closed
isovolumetric contraction and relaxation
semilunar valves are open
ejection
atrioventricular valves are open
passive filling
cardiac muscle properties
- excitability
- conductivity
- contractility
- refractory period
- all or none law
- intercalated discs
cardiac muscles are able to generate electrical impulses spontaneously, allowing rhythmic contractions without external simulation
excitability
sinostrial node and Purkinje fibers are specialized cells within the heart that allows a rapid conduct of electrical impulses
conductivity
cardiac muscle cells can contract forcefully in order to pump blood throughout the body
contractility
ensures complete contraction and relaxation of the heart and can prevent tetanus that may interfere with the heart’s pumping action
refractory period
sustained muscle contraction that occurs when a muscle cell is repeatedly stimulated, causing the refractory period to shorten until the contraction is sustained without rest
Tetanus
the strength of a response of a nerve cell or muscle fiber is not dependent upon the strength of the stimulus
all or none law
there are specialized junctions between the cardiac muscle cells that allows rapid and efficient transmission of electrical impulses (e.g. gap junctions)
intercalated discs
Different types of chemical control
- inotropism
- chronotropism
- dromotropism
- modification of muscular contractility
- affects the force or strength of heart muscle contractions
inotropism
two types of inotropism
- positive inotropism
- negative inotropism
force of contraction is increased resulting to a more forceful pumping of the heart
positive inotropism
example of positive inotropism
- digoxin
- dobutamine
- milrinone
force of contraction is decreased, resulting to a less forceful pumping of the heart
negative inotropism
example of negative inotropism
- flecainide
- disopyramide
- atenolol
- interference with the rate of the heartbeat
- affect the heart rate or the speed at which the heart beats
chronotropism
two types of chronotropism
- positive chronotropism
- negative chronotropism
increase heart rate
positive chronotropism
example of positive chronotropism
- epinephrine
- isoproterenol
decrease heart rate
negative chronotropism
example of negative chronotropism
- digoxin
- metoprolol
- atenolol
affects the conduction velocity of electrical umpulses through the heart’s conduction system
dromotropism
two types of dromotropism
- positive dromotropism
- negative dromotropism
the speed of conduction increases, which allows electrical signals to travel faster through the heart
positive dromotropism
example of positive dromotropism
epinephrine
speed of conduction decreases, which causes the decrease in the speed of electrical impulses in the heart
negative dromotropism
example of negative dromotropism
- digoxin
- atenolol
What is blood
- important for health maintenance and human body life
- delivers oxygen and nutrients
- composed of red blood cells, white blood cells, plasma, and platelets
functions of the blood
- transportation
- regulation
- protection
- supplying oxygen to tissues and cells
- oxygen from lungs to cells, carbon dioxide from cells to lungs
- essential nutrients such as amino acids, fatty acids, and glucose are provided to the cells
- endocrine hormones are delivered to specific cells
- removal of waste materials such as carbon dioxide, urea, and lactic acid
transportation
essential nutrients that are transported via blood
- amino acids
- fatty acids
- glucose
waste materials that are transported via blood
- carbon dioxide
- urea
- lactic acid
what does the blood help regulate
- body temperature
- pH through buffer
- water content of cells
how does the blood protect
- action of white blood cells protects against diseases, infections, and foreign bodies
- clotting prevents blood loss
blood composition
- plasma (46-63%)
- formed elements (37-54%)
components of the plasma
- 92% water
- 7% proteins
- 1% other solutes
- <1% regulatory proteins
different plasma proteins
- albumin (54-60%)
- globulins (35-38%)
- fibrinogen (4-7%)
regulatory proteins
- hormones
- enzymes
other solutes
- nutrients
- gases
- waste
formed elements in the blood
- erythrocytes (99%)
- leukoytes (<1%)
- platelets (<1%)
- transport oxygen to and from the lungs
- small and bioconcave
- hemoglobin is a protein that contains iron and carries oxygen to its destiantion
- production is controlled by the hormone erythropoietin
erythrocytes (red blood cells)
hormone stimulates red blood cell production in response to low partial pressure of oxygen (pO2)
erythropoietin
life span of erythrocytes
120 days
how many erythrocytes are produced by the human body
~2 million every second
have higher red blood cell numbers
males
why do males have higher red blood cell numbers
testosterone is capable of stimulating erythropoiesis
why do infants have higher red blood cell number compared to adults
adaptation to low oxygen conditions
- colorless
- form vital defenses against infection and diseases
- larger than erythrocytes
- have a normal nucleus and mitochondria
leukocytes (white blood cells)
how many leukocytes are there in a microliter of blood
~ 3,700-10,500
what do leukocytes have
normal nucleus and mitochondria
different types of leukocytes
- granular
- agranular
- Contain many visible granules in their cytoplasm
- These granules store enzymes and other components that are released during infections, allergic reactions, and asthma
- nonspecific immunity
granular
types of granular leukocytes
- neutrophils
- eosinophils
- basophils
Contain few or less visible granules in their cytoplasm
agranular leukocytes
types of agranular leukocytes
- lymphocytes
- monocytes
- roughly disc-shaped and small
- produced when large bone marrow cells called megakaryocytes break into pieces
- form platelet plug in homeostasis
- fibrinogen converts fibrin to make a clot that prevents further loss of blood
thrombocytes (platelets)
where are platelets produced from
megakaryocytes, large bone marrow cells, break into pieces
what do thrombocytes form during homeostasis
platelet plug
what is converted to make a clot that prevents further loss of blood
fibrinogen into fibrin
amount of platelets per microliter of blood
150,000-400,000
characterized by presence of antigens on the surface of erythrocytes
AB blood types
are considred the most important and are followed routinely for clinical, diagnostic and forensic purposes
- ABO system
- Rh system
what can blood type incompatibility lead to
- severe disseminated coagulation
- prolonged hypotension
- acute uraemia
- deat
clumping of particles due to the interaction between antigens and antibodies
agglutination
process of converting blood into a semisolid jelly-like substance.
coagulation
where is Rh named after
Rhesus monkeys
occurs when child is Rh positive and mother is Rh negative
mother-fetus incompatibility
disease caused by mother-fetus incompatibility
erythroblastosis fetalis
Involved in control of circulation
- precapillary sphincters
- vasomotion
- hormones
- tiny bands of smooth muscle located at the entrance to capillary beds
- regulate blood flow into the capillaries
- contract or relax in response to body’s needs, controlling the blood supply to tissues and organs
- maintain blood pressure
precapillary sphincters
- rhythmic contraction and relaxation of small blood vessels, capillaried, and primary arterioles
- independent of the heartbeat, respiratory cycles, or neve impulses
- enhanced blood flow for increased delivery and nutrient exchange
- support to metabolic processes by influencing the delivery of nutrients to tissues
vasomotion
stimulation influences the regulation of blood circulation through two main types of control
hormones
two main types of control
- neuronal control
- local control
- adjusts the blood flow
- supplies the heart and the brain
- maintains blood pressure
- limits open capillaries
- regulates capillary flow
- priority system
neuronal control
- prevents large changes in resistance to flow
- controlled by vasodilation or vasoconstriction
local control
what happens to the blood vessels during vasoconstriction
- narrows capillaries
- dilate deeper blood vessels
what happens to the blood vessels during vasodilation
- widens capillaries
- contrict deeper blood vessels
Four types of blood pigments
- hemoglobin
- hemocyanin
- chlorocruorin
- hemerythrin
- iron-containing protein in red blood cells, giving blood its red color
- most common respiratory pigment
- structure allows simultaneous transport of multiple oxygen molcules for efficient delivery
hemoglobin
- circulates freely in the hemolymph rather than being confined to cells
- contains copper atoms, fibing it a blue or green coloration
- colorless when deoxygenated
- oxygen binds directly to copper atoms, functioning well in low-oxygen conditions
hemocyanin
- contains iron atoms and is charcterized by a green-colored protein
- found in annelids
- exhibits high affinity for oxygen, benefician for low-oxygen environments
- green when diluted, reddish when concentrated
chlorocruorin
- found in some marin inverts
- does not contain heme
- oxygen binds directly to its iron atoms
- range from colorless to purplish in response to oxygenation
hemerythrin
where the body relies to maintain pH balance efficiently
blood buffer systems
blood pH range
7.35-7.45
condition of having a lower pH than the normal pH of blood
acidosis
vondition of having a higher pH than the normal pH of the blood
alkalosis
different types of buffer system
- bicarbonate
- hemoglobin
- plasma protein
- phosphate
operates similarly to phosphate buffers, with bicarbonate regulated by sodium in the blood
bicarbonate buffer system
bicarbonate buffer system:
strong acid
bicarbonate produces carbonic acid and sodium chloride
NaHCO3 + HCl -> H2CO3 + NaCl
bicarbonate buffer system:
strong base
carbonic acid produces bicarbonate and water
H2CO3 + NaOH -> HCO3- + H2O
bicarbonate buffer system ratio
20:1 ratio of bicarbonate to carbonic acid
regualted by CO2 expiration through the lung
carbonic acid levels
help dissociate carbonic acid
carbonic anhydrase in red blood cells
what manages bicarbonate levels
renal system which conserves bicarbonate ions
where is the bicarbonate buffer system the primary buffering system of
intersitial fluid surrounding cells
- During the conversion of CO2 into bicarbonate, hydrogen ions liberated in the reaction are buffered by hemoglobin, which is reduced by the dissociation of oxygen
- in pulmonary capillaries, process reverses to re-form CO2, allowing it to diffuse into air sacs for exhalation
hemoglobin buffer system
- amino acids contain positively charged amino groups and negatively charged carboxyl groups
- charged regions of proteins can bind to hydrogen and hydroxyl ions
plasma protein buffer system
protein buffer accounts for how much of the buffering system in blood
2/3
use of phosphate to buffer
phosphate buffer system
two forms of phosphates in the blood
- sodium dihydrogen phosphate (Na2H2PO4-), weak acid
- sodium monohydrogen phosphate (Na2HPO4 2-), weak base
phosphate buffer system:
strong acid
- forms sodium dihydrogen phosphate, weak acid, and
- sodium chloride
Na2HPO4 + HCl -> NaH2PO4 + NaCl
phosphate buffer system:
strong base
- reverts to Na2HPO4 2-, weak base, and
- produces water
NaH2PO4 + NaOH -> Na2HPO4 + H2O
mechanism that leads to cessation of bleeding from a blood vessel
hemostasis
Steps in Hemostasis
- vascular spasm
- platelet plug formation
- coagulation of blood (clotting)
- initial response in primary hemostasis
- occurs following damage to endothelial cells during vascular rupture
vascular spasm
key mediator of vascular spasm
endothelin-1, vasoconstrictor
freely floating platelets begin to clump together, forming sticky aggregates
initial clumping
platelets attach to the exposed vascular lining and collagen due to spiked structure
attachment
- stabilizes plateleg plug and promotes further accumulation over the damaged endothelium
- attached platelets release substances, mainly ADP, which attract more platelets to the site
role of von Willebrand factor
temprary seal which are combined platelets bound to collagen and the endothelial lining
platelet plug
- process of blood solidification through fibrin fiber formation, marking the secondary hemostasis stage
- results in a stable, solid blood clot
coagulation of blood (clotting)
key step in the coagulation process
conversion of prothrombin to thrombin
forms the mesh structure of the blood clot
conversion of fibrinogen to fibrin fiber
Two different pathways in the coagulation process
- extrinsic pathway
- intrinsic pathway (contact activation pathway)
- Activated by internal damage to the vascular endothelium, such as by platelets, chemicals, or collagen
- slower than the extrinsic pathway, but more important
- measured clinically by the partial thromboplastin time (PTT).
intrinsic pathway
how is the intrinsic pathway measured
partial thromboplastin time (PTT)
- Activated by external trauma, such as blood escaping from the vascular system.
- quicker than the intrinsic pathway.
- measured clinically by the prothrombin time (PT)
extrinsic pathway
how is the extrinsic pathway measured
prothrombin time (PT)
- where both pathways eventually meet a
- where factor X is activated and fibrinogen is converted into fibrin to form a blood clot.
the common pathway
what happens in the common pathway
- factor X is activated
- fibrinogen is converted into fibrin to form blood clot
degradation of fibrin fiber
fibrinolysis
induced chemical or physical stress
thrombolysis
aggregation of particles to form a single large solid mass
agglutination
gelling or clumping of particles
coagulation
what is formed during agglutination
large solid mass of small particles
what is formed during coagulation
clump of small particles
where does agglutination mainly occur
between antigens and antibodies
where can coagulation be observed
blood
Common Diseases of the circulatory system
- arteriosclerosis
- myocardial infarction (MI)
- hypertension
- abdominal aortic aneurysms
- heart arrhythmia
thickening of the walls of arteries, reducing function
arteriosclerosis
specific form of arteriosclerosis where plaque builds up on the endothelium of arteries, causing them to narrow and reduce oxygen delivery to the tissues
atherosclerosis
artery that supplies blood and oxygen to the heart gets blocked
myocardial infarction (MI) or heart attack
measures how hard your heart works to push blood through your arteries
blood pressure
- force of blood is too high
- can harm your heart and lead to problems like heart disease, stroke, or kidney disease
hypertension
- bulge in a weak spot of the aorta in the abdomen
- sometimes, it can stay small and not cause any issues
- if it grows larger, pain might be felt in the abdomen or back
abdominal aortic aneurysms
- irregular heartbeat that happens when the electrical signals controlling the heart beats aren’t functioning correctly
- can result in the heart beating too fast, too slow, or in irregular pattern
heart arrhythmia
