Circulatory System Flashcards
Blood circulation
what are the 2 main circuits? Describe both
Pulmonary - de-O2 from heart -> lungs -> back to heart
systemic - O2 blood from heart -> body drop off O2 -> pick up CO2 -> back to heart
name the pericardial layers of the heart and related function (superficial to deep)
fibrous - connected to diaphragm
parietal - contains fluid to reduce friction
visceral - touches heart wall
list the heart wall layers
epicardium - outermost; made of connective tissue
myocardium - made of cardiac muscle; thickest layer
endocardium - innermost, smoothest layer, continuous w/ blood vessel lining; allows blood to flow easily
Blood flow path through the heart
heart, venae cavae (superior/inferior), right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary trunk, pulmonary arteries to lungs, pulmonary capillaries (gas exchange), pulmonary veins to heart, left atrium, bicuspid valve, left ventricle, aortic valve, aorta, body, back to heart
describe the atria (chambers) of the heart
top chambers, R & L, have thin walls bc not under pressure (only receive blood)
R&L are separated by interatrial septum
describe the structure of the ventricles
Describe structural differences between right and left ventricles and why these differences occur
How are the two ventricles separated?
thicker walls bc push blood out thus under more pressure
right - smaller and thinner; push blood out to lungs
left - larger, thicker, push blood out to body so more effort is required
separated via interventricular septum
what do the atriaventricular valves separate?
describe and name the 2 AV valves
define cardiac skeleton and it’s function
separate atria and ventricles
Right - tricuspid valve = 3 cusps Left- bicuspid/mitral valve
made up of chordae tendinae and papillary muscles - support and open/close valves
what do semilunar valves do?
name both semilunar valves and describe their structure
control movement of blood out of heart
pulmonary and aortic
- have 3 cusps so cardiac skeleton is not required
which arteries supply the heart with blood?
how does the heart get supplied w/ blood?
coronary arteries
through relaxation
define anatomoses
what is their significance?
connections btwn blood vessels to allow for multiple pathways for blood to reach target organ
in case of obstruction, other pathways for blood to flow
what are the 2 phases of the cardiac cycle and what occurs in each phase?
Systole - contraction
diastole - relaxation
list the steps of the cardiac cycle and describe each step
Atrial systole - atria contract, fill ventricles (AV valves = open)
atrial diastole begins - atria relax and remain relaxed until next cardiac cycle
ventricular systole early - ventricles contract while AV valves close, semilunar valves are still closed which means blood cannot move thus allowing pressure to build AKA isoduretic contraction
Ventricular systole late - pressure builds, opening semilunar valves and blood is ejected (ventricular ejection) ventricular diastole - ventricles relax, semilunar valves close, atria fill w/ blood while AV valves are closed
what unique feature does cardiac muscle have? describe
what does this feature allow to heart to do? what is the benefit of this feature?
intercalated discs connect cardiac muscle cells
- gap junctions = allow ions/action potentials to move btwn cells
-desmosomes = anchor cells together, preventing cell separation
allow all cardiac muscle cells to contract/relax at same time AKA functional syncytium = more force to push blood out
describe Sinoatrial (SA) node
pacemaker that sets heart rate (HR)
-pacemaker cells conduct electrical impulses via spontaneous depolarization
describe AV node
has pacemaker cells, doesn’t set HR
- can maintain HR at lower rate if there’s damage to SA node
what do purkinje fibers trigger?
ventricular systole
define EKG
electrocardiogram - shows electrical changes in heart
define arrhythmia
abnormal EKG
What effect does the parasympathetic NS have on HR
decreases HR via vagal nerves
what effect does the sympathetic NS have on HR
increases HR and force of contraction
what happens if the vagal nerves are cut?
HR increases
define cardiac output (CO)
volume of blood that leaves ventricles each minute
what information is needed to find CO
HR and stroke volume (SV)
define stroke volume
amount of blood that leaves ventricles each CYCLE
How does changing CO affect blood pressure?
lower CO = decrease BP
higher CO = increase BP
what are chronotropic agents?
Postive vs. Negative
factors that change HR
postive = increase
negative = decrease
what is end-diastolic volume?
amount of blood in the ventricles at the end of diastole
what is end-systolic volume?
amount of blood left after contraction
how is SV found?
SV = EDV - ESV
*factors that influence SV actual influence EDV/ESV
define venous return and how it affects SV
volume of blood returning to heart, determines EDV
- pre-load is the stretching of the heart wall due to load (how much blood do you have); greater volume - greater preload - larger SV = larger CO
define inotropic agents
external factors that change SV by altering force of contraction (contractibility)
negative - decrease
positive - increase
define afterload
resistance in arteries
- more resistance = less blood entering ventricles = smaller EDV = smaller SV
define edema
accumulation of fluid in interstitial spaces surrounding cells
list the 5 types of blood vessels
arteries - carry blood away from heart arterioles - smaller diameter capillaries - site of gas exchange veins- carry blood back to heart venules - smaller diameter
List and describe the 3 tunics of blood vessels
tunica interna - lines lumen, smooth for blood flow ease (touches blood)
tunica media - smooth muscle layer, responsible for vasoconstriction and vasodilation
tunica externa - anchors vessels, mostly connective tissue
What are some characteristics of arteries? how do they relate to its function?
strong and elastic
- under lots of pressure bc carries blood away
What are the 3 classes of arteries? describe structure and how it relates to function of each
- elastic - contain lots of elastic fibers, under greatest amount of pressure, ex. Aorta
- muscular - not as many elastic fibers, sill strong
- arterioles - smaller in diameter (lose some of tunica media), thick tunica media = keep structure when blood’s removed
What are some characteristics of capillaries?
How does this relate to function
smallest diameter, very thin only composed of endothelium (tunica Interna)
thinner membranes allow for faster diffusion of gases (function = gas exchange)
What are the 3 types of capillaries? describe structure, features, and how they relate to function. give example of locations w/in body
continuous - no space btwn cells, continuous membrane; locations - smooth cardiac/skeletal muscle
fenestrated - small pores in membrane, increases permeability; locations - endocrine organs/kidneys
sinusoid - large gaps btwn cells = increase permeability; locations - spleen, liver, bone marrow
describe veins/venules
thin tunica media/thick tunica externa = if blood is removed, vein will collapse bc structure is lost
contains valves which keep blood from moving back to heart, ex. lower extremities, valves keep blood from pooling in feet
can serve as blood reservoirs
what is the circulatory pathway of blood vessels?
artery, arterioles, capillaries, venules, veins, heart
what are some alternative pathways for blood vessels?
anastomoses - join vessels
portal system - allow blood to move directly btwn capillary beds EX. hepatic portal system connect digestive organs to liver
what is capillary exchange?
a vital combination of diffusion, filtration, and osmosis
where does filtration occur in capillary exchange
along the capillary
On what end of the capillary does reabsorption occur? venous end or artery end
venous end
define blood pressure
measurement of systolic / diastolic pressure
force of blood pushing against vessel walls
where is BP usually taken?
what is considered a normal BP?
where is pulse taken?
taken at brachial
120/80
radial artery
define blood volume and what is the average in L
how does it effect BP
sum of formed elements and plasma volumes in vascular system, average 5L based on body size
higher blood volume = higher BP
lower = lower BP
define peripheral resistance
how does it effect BP
friction btwn blood and blood vessel walls
larger diameter = less resistance = lower BP
small diameter = more resistance = higher BP
longer vessel = more resistance
shorter = less resistance
How does vasoconstriction and vasodilation effect BP?
vasoconstriction = increase BP vasodilation = decrease BP
how does blood viscosity effect BP
viscosity = thickness which effects blood flow ease
higher viscosity = more resistance = higher BP
lower viscosity= less = lower BP
How is BP regulated in the short term
via neural regulation (autonomic NS)
2 cardiovascular centers in medulla
- cardiac center: responsible for CO; parasympathetic = increased HR/SV/CO = increased BP; sympathetic = decreased HR/SV/CO = lower BP
-vasomotor center controls vasodilation and vasoconstriction; if BP increases – dilation; decreases –constriction
describe long term regulation of BP
via hormone regulation
- angiotensin II = vasoconstrictor, stimulates thirst center, also stimulates ADH and aldosterone
- ADH decreases urine output
- aldosterone - increases Na+ absorption –maintain H2O and blood volume
- atrial natriuretic peptide - released from heart, used to lower BP by stimulating vasodilation and increasing urine output
what is Hypovolemic shock?
caused by severe blood/fluid loss
blood vessels constrict to increase BP temporarily
HR will increase; if fluid loss continues – sharp drop in BP–heart goes into shock = fatal
list some functions of blood
transport O2, nutrients, wastes, hormones
aid in defense via WBCs
distribute body heat
help maintain ion concentrations in tissue fluid
what are the two main components of blood?
formed elements - WBCs, RBCs, platelets
plasma -mostly water
list some characteristic of blood
temp about 100.4 degrees F
5x more viscous than H2O
slightly alkaline
where are blood cells made
red bone marrow from hematopoietic cells
what are the 2 types of hematopoietic (stem) cells? What blood cells do they make?
myeloid stem cells - RBCs, platelets, most WBCs
lymphoid - lymphocytes (WBC)
what are some characteristics of erythrocytes?
main function?
small, biconcave shape, make up 1/3 of the trillion body cells, large surface area = more room for diffusion and hold more hemoglobin
flexible = move through narrow spaces
cannot repair/reproduce
transport O2
what is hemoglobin?
pigment protein made of 4 chains, each chain has heme unit that hold iron and where O2 binds
What is the function of leukocytes (WBCs)? what are some of their properties?
function = defense
- diapedsis =can move out of circulation into tissues
- phagocytotic
- respond to chemotaxis - movement toward chemicals
what are the 2 categories of WBCs
granulocytes and agranulocytes
Which WBCs are granulocytes
neutrophils - multi lobed nucleus, most abundant
eosinophils - bi lobed nucleus, help moderate/reduce inflammation (role in allergies)
basophils - release histamine to promote inflammation and heparin which thins blood to increase blood flow to infection site
which WBCs are agranulocyes
monocytes - largest WBC, phagocytotic
lymphocytes - large round nucleus takes up most of the cell, can make “memory cells”
define leukocytosis
WBCC < 10,000 = acute infection
define leukopenia
WBCC below 4,500 = sign of long-term/chronic infection
what is a normal WBCC?
4500-10000
describe characteristics of blood platelets (thrombocytes)
fragments; short life cycle; role = help w/ blood clotting
release seratonin to help with vessel constriction; amount in blood varies but higher number when an injury occurs
what are the functions of blood plasma?
transport, regulate blood pH, regulate ion and H2O balance
what are the 3 plasma proteins from most abundant to least?
albumins, gobulins, fibrinogens
function of albumins
regulate osmotic pressure in vessels
function of gobulins
transport
function of fibrinogens
blood clotting
List phases of Hemostasis (blood clotting)
vascular phase - vasospasm; constricting smooth muscle to prevent blood loss
platelet phase - make platelet plug; platelets stick to cut and attract more to make temporary plus and release seratonin to continuously constrict vessel
coagulation - form blood clot in series of reactions that rely on each other to happen
clot retraction - shrink clot to repair vessel damage
what are the 2 pathways that result in a blood clot?
extrinsic = damage outside vessel intrinsic = damage inside goal = convert fibrinogen (dissolvable) to insoluble fibrin (plasma protein)
define antigens and antibodies
antigen - surface molecule allow to recognize itself
antibodies - bind to specific antigens
what is agglutination and what causes it
clumping due to mixing incompatible blood types
