CIRCULATORY SYSTEM Flashcards
Blood function
transport
regulation
protection
blood transport
to deliver oxygen and nutrients to, and remove wastes from body tissues and cells.
oxygen
hormone
co2
nutrients
blood regulation
Blood helps maintain homeostasis of all body fluids
proteins and chemicals in blood act as pH buffers
blood osmotic pressure helps regulate the water content of body cells
blood protection
White blood cells protect against;
external threats, such as bacterial pathogens
internal threats, such as cells with mutated DNA that could become cancerous, or body cells infected with viruses.
Blood can clot, which protects against excessive blood loss and initiates the healing process.
blood characteristics
bright red when oxygenated
dark red when not
thicker then water
alkaline
composition of blood
Plasma- mainly water but 3 ( albumin, globulins, fibronogen)
formed elements
red blood cells
haemaglobin
Albumin
made by liver
transport fatty acids, hormones, ions
helps draw water from tissue
globulins
immunoglobulins (antibodies) - made by plasma cells, bind to specific antigens and mark them for destruction by specialised white blood cells
alpha and beta globulins - made by the liver, transport iron, lipids, and the fat-soluble vitamins A, D, E, and K to the cells; like albumin, they also contribute to osmotic pressure.
fibronigons
made by the liver
essential for blood clotting - form clots and produce long, insoluble strands of fibrin.
red blood cells
no nucleus
no mitacondria
no endoplasmic reticulum- so dont sysntheise proteins
biconcave
haemaglobin
found in red blood cells
it has iron and oxygen binds to it
haematostasis
process by which the body seals a ruptured blood vessel and prevents further loss of blood
vascular spasm
platlet plug
colagulation
vascular spasm
damage blood vessel casuses contraction of smooth muscle to vasoconstrict to decrease blood flow to the area
endothelial cells release endothiles hormones
platelet plug
platelets bind to the exposed collagen at the site of blood vessel damage, and become activated. Activated platelets bind to other platelets and the endothelial lining forming a platelet plug. Activated platelets also release chemicals into the plasma that contribute to haemostasis
colagulation
complex cascade of enzymatic reactions resulting in the conversion of fibrinogen (a soluble protein) into fibrin (an insoluble protein). As the fibrin mesh gorws, plateletes and blood cells are trapped, forming a clot that seals off
extrinsic pathway for colagulation
triggered when clotting factors outside the blood vessel leak into blood
fewer steps
intrinsic pathway for colagulation
triggered when clotting factors come into contact with substances inside the blood vessel
more steps
what do contractive proteins do in clotts
decreases the size of the damaged area
decreases the residual bleeding and stabilises the injury
permits healing.
fibronolysis
proccess clot is going away
thrombin and tissue plasminogen activator (t-PA) activate plasminogen
plasminogen produces plasmin
plasmin digests fibrin strands.
blood groups
detremined on presence of A or B surface antigen
reheus system is detecting of the D surface antigen
if you have it it is positive if not its negative
structure of the heart layers
3 layers- epicaridum, myocaridum endocardium
outermost layer of the heart
pericarium
protects and confines the heart it is a doubled layered membrane ( serous membrane )
pariteal- outer visceral inner
they contain fluid which lubes
myocardium
cardiac muscle tissue and is responsible for the pumping action of the heart.
endocardium
layer of endothelium with an overlying thin layer of connective tissue. It forms the lining of the chambers of the heart and covers the values of the hear
Pulmonary pump
blood to lungs
Systemic pump
delivers blood to/from the body
deoxygenated blood from the body enters the
right atrium via superior/ inferior venna carva
tricsupid valve is between
right atrium and right ventircle
doxygenated blood leaves heart via
pulmary artery from left venticle
oxygenated blood arrives at the heart
from the lungs to the left atrium from pulmonary vein
oxygenated blood leaves heart via
aorta from left venticle
bicuspid valve
seperates left atrium and ventricle
sinoatrial node
autorythmic- doesn’t need stimulisation
they depolarise
then sends electrical message to both sides
makes heart contract
it is the pace maker
atriventricular node
recives electrical response and trnasfer to bundles branches to inside
and then outside via perkinjie fibres
how does heart contract
sa node depolarises
message goes to AV node then to
AV bundle, bundle branches and perkinjie fibres
mechanical action of heart
inovate ventricle walls
P wave
represent depolarisation of atria
QRS wave
represent depolarisation of the ventricles
repolarisation of atria hiden by this
T wave
represents repolarisation of the ventricles
cardiac cycle
atrial systole- contract atria
atrial dyistole- relac
ventricular systole- contract
ventricular dyistole
atria contract
atrium get smaller and pressure increases
aorta contract
aorta gets smaller increase aortic pressure
ventricle contracts
ventricle pressure increase
arteries
efferent away from the heart
thick muscular walls
no valves
withstand high pressure
small lumen
veins
thin walls
large lumen
valves
low pressure
smooth muscle contract to pump blood back to heart
capillaries
connect the smallest arteries (arterioles) and the smallest veins (venules). The thin wall of capillaries allows the exchange of nutrients, dissolved gases, and wastes between blood and interstitial fluid.
Tunica intima
inner most layer of blood vessels
Tunica media
middle layer smooth musle contracts for vasoconstirction
Tunica externa
outermost layer is a substantial sheath of connective tissue primarily composed of collagenous fibers, stabilising and anchoring the blood vessel.
mean artiral pressure
made of both dystolic and systolic pressure
cardiac output
HR X SV
AMOUNT OF BLOOD EJECTED BY THE VENTRICLE EACH MINUTE
TOTAL PHERIPHERAL RESISTANCE
vessel diameter
length
vasoconstriction
vasodilation
influncce this
fluid exits sapilary why
because capilary hydrostatic is greater then blood collodial pressure
fluid is reabsobed by capilary
capilary hydorstatic is less then blood collodial
blood flow is determind from
high pressure to low pressure
Blood pressure MAP
CO x TPR
CO
Cardiac output = SV x HR
temperature pulse respiration is limited by
sysmpathetic nervous system
vasoconstriction increases resistance
vasodilation decrease resistance
parasympathetic has no effect on blood vessel diameter
Cardiac reserve:
ifference between resting and maximal CO
regulation of heart rate
Noradrenaline (& adrenaline) acting on β1 adrenergic receptors.
Effect: heart rate increases
Parasympathetic activity: Vagus nerve (cranial nerve X) via acetylcholine acting on muscarinic receptors.
Effect: heart rate decreases
Other factors influencing HR:
Positive chronotropic factors = increase heart rate, for example adrenaline, caffeine
Negative chronotropic factors = decrease heart rate, for example Beta-blockers, such as Propranolo
tachycardia
abnormal condition of a fast heart rate
bradycardia
abnormal condition of a slow heart rate
regulation of stroke volume
Intrinsic control
If ventricular wall stretched before contraction, contractile force increases
If End Diastolic Volume ↑ (meaning the ventricle chamber is stretching and putting pressure on ventricular wall) → SV ↑ → CO ↑
Extrinsic control: stimulation of sympathetic activity
Noradrenaline (& adrenaline injection) acting on β1 adrenergic receptors.
Effect: increased contractile force
autoregulation
at the blood vessel site causing immediate localised homeostatic adjustments
autoregulation that cause vasodilation
Hypoxia: decreased partial pressure of O2
Hypercapnia: increased partial pressure of CO2
Acidosis: decreased pH or increased concentration of H+
Hyperkalaemia: increased concentration of K+ extracellularly
Increased adenosine concentration
Increased temperature
Increased osmolarity
neural machanisim
espond quickly to changes (such as sympathetic system):
Cardiovascular centers and vasomotor centre in the medulla oblongata:
Vasomotor center = A cluster of sympathetic neurons in the medulla that oversee changes in blood vessel diameter
Part of the cardiovascular center, and work along with the cardiac centers
Maintains vasomotor tone (moderate constriction of arterioles) receives inputs from baroreceptors, chemoreceptors, and higher brain centers.
endocrine mechanism
long pathways
ADH
RAAS
EPO
RAAS
Renin-Angiotensin-Aldosterone
increase blood pressure increase blood volume
aldostrone triggers sodium reabsorption
ADH
INCREASE BLLOD PRESSURE INCREASE BV
EPO
Erythropoietin
increase blood pressure
baroreceptors
located in charotid sinus and aortic arch
respond to the pressure in the wall
send action potential to medulla
if increase send greater number of ap to medulla
chemoreceptors
eceptors sensing changes in the composition of arterial blood.
peipheral and central
peripheral chemoreceptors
present in the carotid and aortic bodies
Highly sensitive to hypoxia
Moderately sensitive to hypercapnia and acidosis
centeral chemoreceptors
located in the medulla oblongata
Highly sensitive to hypercapnia and acidosis
a decrease in total body water occurs in human body. This will lead to:
Decrease in blood volume
Increased blood viscosity
Sluggish blood flow → more work for heart
RBC become more deformed leading to
‘Stiffer’ membranes
More resistance in microcirculation
Impaired oxygen delivery to tissues
anemia
s a condition in which there is a lack of healthy red blood cells to carry adequate oxygen to body cells. It is Associated with:
↓ O2 delivery
Increased morbidity and mortality
age changes to blood vessels
1) Arteries become less elastic:
Due to decrease production of elastin protein by fibroblast
Pressure changes can cause aneurysm
2) Increase of calcium deposits on vessel wall → atherosclerosis and increased risk of stroke or infarction
3) Decrease of venous return:
Due to venous valve deterioration
Lack of movement
Dehydration
heart age changes
Reduced maximum cardiac output (in response to exercise or stress)
Cardiomegaly increases, thickening of the left ventricular wall
Decrease of contractility (cardiac cells less efficient to contract)
Changes in conductivity due to:
Reduction of number of pacemaker cells
Increase of fatty and fibrous tissue infiltration of SA node
Increase of scar tissue leading to reduction of heart conduction → heart block → slower heart rate
isovolumetric
contraction occuring but blood is not going anywhere
what is the sound of the heart
blood hitting the valve
what happens when contraction of the atrium
depolarisation occurs
AV node will delay message why
to make sure av valves are closed and ventricles are full
pre-load
the stretch of the heart muscles as the heart files
increase in pre load leads to
increase in blood in the ventricles
increase end diastole volume
increase stretch of ventricle wall
increase sacomere length and contractible force and blood ejects from the heart at greater volume
baroreceptors detect
vascular stretch
