CV system Part 2 Flashcards
functions of blood
- transport: blood gases, nutrients, wastes, processed molecules, regulatory molecules
- regulation: pH, osmosis, body temp
- protection against foreign substances: antibody production
- clot formation: repair damaged tissues, stops clot formation
regulation as a function of blood
pH of blood is kept b/w 7.35 and 7.45
- osmosis: maintenance of fluid balance
- body temperature regulation with vasodilation and constriction
composition of blood
blood consists of 8% if our total body weight (4-6 L in adults)
- plasma: 55%
- formed elements: 45%
- buffy coat: layer when centrifuged composed of platelets and WBC
bicarbonate system
works as a buffer to avoid any large changes in blood pH
- also a way of carrying CO2 in our blood
blood plasma
the fluid portion that makes up 55% of our blood
7% proteins
91.5% water
1.5% other solutes
formed elements (blood)
45% of our blood
- includes platelets, WBC and mostly RBC
describe blood as a connective tissue
extracellular matrix: plasma
cellular component: formed elements
colloid
a fluid that contains suspended substances
- water, proteins, ions, nutrients, waste products, gases, regulatory substances
proteins present: albumins, globulins, fibrinogens
albumins
a protein present in plasma
- most abundant (58%)
- fairly small protein, doesn’t leave blood supply or pass into tissues therefore keeps concentration gradient regular (fluid comes into blood to keep it from becoming too concentrated)
- transports FAs, bilirubin and thyroid hormones
globulins
a protein present in plasma
- 38% of plasma proteins
- antibodies, transport lipids (cholesterol), iron, sex hormones (also cholesterol based)
- there are alpha, beta and gamma types
fibrinogen
a protein present in plasma
- 4% of plasma proteins
- important in blood clotting
components of formed elements
RBCs: erythrocytes
WBCs: leukocytes
platelets: thrombocytes
red blood cells
aka erythrocytes - make up 95% of formed elements
- biconcave discs with no nucleus, mitochondria or organelles
- contain hemoglobin which transports O2 and CO2
- converts CO2 and H2O into carbonic acid (H2CO3)
white blood cells
aka leukocytes - makes up 5% of formed elements
- 2 types: granulocytes and agranulocytes
granulocytes
one type of WBC
have large granules and have multi-lobed nuclei
3 types:
- neutrophils, eosinophils, basophils
agranulocytes
one type of WBC
have small granules and nuclei are not lobed
2 types:
- lymphocytes and monocytes
platelets
aka thrombocytes
- cell fragments that form platelet plugs and release chemicals necessary for blood clotting that signal neighbouring cells to come help
hematopoiesis/ hemopoiesis
the process of blood cell production
- when occurring post-birth, happens in red bone marrow and lymphatic system
stem cells
all formed elements are derived from a single population (hemocytoblast) found in red bone marrow
- basically differentiate into different types of formed elements
proerythroblasts
become red blood cells
reticulocyte
immature RBC that has no nucleus or organelles
- when released into blood, it takes 2 days to become a RBC
myeloblasts
differentiate into the granulocytes: basophils, neutrophils and eosinophils
lymphoblasts
become lymphocytes
monoblasts
become monocytes
megakaryoblasts
parts break off and cell fragments are known as platelets
amount of red blood cells found in adult woman and adult male
men: 5.4 million/uL
women: 4.7 million/uL
shape of RBC
8um diameter, biconcave disc that creates more surface area for gas exchange to occur
components of a RBC
- one third hemoglobin
- two thirds lipids, ATP and carbonic anhydrase
what do RBC transport
- oxygen: 98.5% is bound to Hb
- carbon dioxide: 23% is bound to Hb, 7% dissolved in plasma and 70% dissolved as bicarbonate
- hydrogen ions: generated by carbonic anhydrase reaction, also play a role in altering pH changes
hemoglobin
composed of:
- 4 globin molecules
- 4 heme molecules that each contain 1 iron atom which transports O2 and CO2 (carbonic anhydrase is involved)
- CO2 bind to globin and O2 binds to iron
3 states of hemoglobin
- oxyhemoglobin
- deoxyhemoglobin
- carbaminohemoglobin
oxyhemoglobin
transporting oxygen
- can be bound to alpha or beta globins
deoxyhemoglobin
has no oxygen bound
- does’t usually happen, but could during intense exercise
carbaminohemoglobin
is transporting CO2
erythropoiesis
RBC production, takes about 4 days
- 2 million RBCs are degraded per second but 25 trillion are in circulation
- and RBC lasts for 120 days in circulation: they can’t repair themselves once damaged because they have no organelles
erythropoietin
a hormone produced by the kidney that stimulates RBC production when blood O2 levels are low
- released based on oxygen delivery to the kidney
RBC recycling
- natural degeneration of RBCs: death and phagocytosis by macrophages in spleen, liver or red bone marrow
- separation of components
- globin protein: amino acids get recycled
- heme: iron is removed and recycled in the liver, spleen and red bone marrow ; heme is then transported through blood on transferrin (a carrying protein)
- iron-free heme: converted into bilirubin which creates colour in bile, urine and feces
function of WBCs
- protect body against microorganisms and remove dead cells and debris
- nucleated, no hemoglobin so not involved in transport of O2
- have different types of movements
types of WBC movements
3 types:
- ameboid movement
- diapedesis (emigration)
- chemotaxis
ameboid movement
- plasma membrane of WBC creates armlike projections that grab out and extend to digest things
diapedesis
aka emigration
- cells become thin and elongate and either move between or through endothelial cells of capillaries
- WBC leave CV system and enter into tissues surrounding blood supply
chemotaxis
- attraction to and movement toward foreign materials (which release chemicals that attract WBC) or damaged cells
- phagocytize bacteria and die off: this accumulation of WBC is pus
types of WBC
5 types:
- neutrophils
- eosinophils
- basophils
- lymphocytes
- monocytes
neutrophils
most abundant type of WBC (60%)
- 2-5 lobes on nuclei
- live for 10-12 hours in circulation, 1-2 days in tissues, and thus are produced more frequently
- phagocytize bacteria/foreign matter (are first responder by secreting lysozyme, an enzyme that metabolizes bacteria)
eosinophils
account for 2-4 % of WBCs
- nuclei have 2 lobes
- active in allergic rections, don’t want inflammatory response to get out of hand so that destroy inflammatory chemicals like histamine to reduce inflammation
- releases chemicals that help destroy larger bacteria such as tapeworms, flukes, pinworms, hookworms
basophils
account for 0.5-1% of WBCs
- create inflammatory and allergic response of tissues
- produce histamine which causes vasodilation and bronchial constriction
- produces heparin which inhibits blood clotting
- allows capillaries to be more permeable to WBC entering tissues
lymphocytes
account for 20-25% of WBCs
- are produced in red bone marrow and proliferate in lymphatic tissue
- produce antibodies that destroy bacteria, tumour cells, and cells containing viruses
monocytes
account for 3-8% of WBCs
- largest in size
- become macrophages after 3 days
- phagocytic cells increase with chronic infection
- leave circulation and enter into tissues to digest bacteria
how are platelets formed
they are cell fragments that are pinched off of megakaryocytes in red bone marrow
how do platelets work
surface glycoproteins make them sticky to allow them to adhere to molecules like collagen
platelet plug formation
- platelet adhesion to collagen fibres when it and the endothelium becomes damaged
- platelet release reaction: causes platelets to send signals that starts the clotting process
- platelet aggregation forms platelet plug
types of arteries
- elastic
- muscular
- arterioles
elastic arteries
include pulmonary trunk, aorta and immediate branches
- made up of fewer muscle fibers and more elastic fibers to allow for acommodation for pressure changes
muscular arteries
include branches of arteries
- made up of a large number of smooth muscle fibers
- can vasodilate and vasoconstrict, directing blood flow to where the body needs it
arterioles
- important for pressure maintenance
- smallest
- are responsible for directing blood flow to capillaries
capillaries
site of gas, nutrient, and waste exchange within tissues
blood vessel structure
3 general layers:
- tunica interna/ tunica intima
- tunica media
- tunica externa/ tunica adventitia
tunica intima
innermost layer
- endothelium: simple squamous epithelium
- basement membrane: collaged fibers that hold endothelial layer together and provide strength to inside walls
- internal elastic lamina: found in arteries only; has holes that allow molecules to move through, also gives arteries elastic properties
tunica media
middle layer that contains:
- smooth muscle: more in arteries than in veins
- external elastic lamina: present in arteries only and has holes to allow movement, gives arteries elastic properties (same functions as internal elastic lamina)
tunica externa/ tunica adventitia
outermost layer, adjacent to surrounding tissue
- contains collagen and elastic fibers
- CT for attaching blood vessels to surrounding tissues (collagen for larger, areolar for smaller vessels)
- nerve supply and blood vessels present here for larger blood vessels
elastic arteries
conducting arteries
- have a large diameter
- more elastic fibers in medial layer especially than smooth muscle
- function as pressure reservoirs that stretch to accommodate a large volume of blood
ex. pressure in aorta has to be larger than in left ventricle in order for blood to leave the heart during ventricular systole
muscular arteries
distributing arteries
- medium in diameter
- we have more of these in the body than other types of arteries
- more smooth muscle fibers, fewer elastic fibers
- distribute blood to various parts of the body with vasoconstriction and vasodilation
arterioles
transport blood from small arteries to capillaries
- smallest arteries where the 3 tunics can still be differentiated,
- outer layer is more areolar CT; has fewer muscular fibers
- terminal end called the metarteriole
metarteriole
the end of an arteriole where it enters the capillary bed
- it still has some smooth muscle around it but isn’t the same as a capillary (muscle cells get to be fewer and fewer)
histology of capillaries
- only has endothelial layer and basement membrane layer
- microscopic vessels that usually connect arterioles and venules
- because the walls are so thin and delicate (therefore pressure needs to drop a lot) capillaries permit exchange of nutrients and wastes between blood and tissue cells
2 ways that blood flow through capillaries
- precapillary sphincters relax and allow blood to flow into capillary beds to slow bloodflow through thoroughfare (ex. during exercise to slow this down and decrease BP and allow gas exchange)
- precapillary sphincters contract and blood flows through the thoroughfare channel faster , blood does not enter the capillary beds
thoroughfare channel
where the blood flows through and gas exchange occurs; the rest of the capillaries are simply there to increase SA and slow down rate of flow through capillary beds
post capillary venule
is structurally the same as a capillary
intercellular cleft
the small space between endothelial cells
types of capillaries
continuous
fenestrated
sinusoids
continuous capillaries
- have no gaps b/w endothelial cells
- are less permeable to large molecules than other capillary types
- only blood gases and nutrients move through the walls
ex. muscle and nervous tissue
fenestrated capillaries
- have pores (fenestrations) in endothelium
- areas where cytoplasm is absent and the plasma membrane is made up of thin, porous diaphragm
- highly permeable
ex. intestinal villi, ciliary process of eye, choroid plexus, glomerulus of kidney
sinusoid capillaries
- large diameter with large fenestrae
- less basement membrane (it’s incomplete)
ex. endocrine glands, liver, bone marrow (allow large molecules to cross)
venules
drain capillary network
- endothelial cells and basement membrane with a few smooth muscle cells (on muscular venules only)
- as diameter increases, the amount of smooth muscle also increases
veins
formed from the union of several venules
- thinner tunica interna and media layers, thicker tunica externa: has less elastic tissue and less smooth muscle than arteries causing them to be less stretchy
- VALVES
- diameter of a vein is larger than it’s matching artery
valves
found in all veins >2mm in diameter
- folds in intima layer that overlap, a lot like semilunar valves
- more valves are in veins in lower extremities than in veins of upper extremities
- function is to prevent backflow of blood
- muscle pumping: skeletal muscle contracts and squeezes veins when you move, pushing blood through the valves
varicose veins
dysfunctional valves, found more in lower extremities
- leak under pressure, an over stretching of veins when blood pools
- caused by pregnancy (fetus blocks off blood flow), defective valves (possibly genetic)
- symptoms: swelling, pain, ulcers in ankles (severe), usually problems with more superficial veins
vasa vasorum
blood vessels that supply the walls of arteries and veins (outer tunics, found right in tunica externa), that penetrate the walls of a blood vessel from the exterior
- the blood vessels that supply our blood vessels that are greater than 1mm in diameter
portal veins
2 in-series capillary networks without going back to the heart in between
- hepatic portal veins: bed from GI system and spleen to runs to bed in the liver
- hypothalamohypophysial portal veins: bed in the hypothalamus runs through infundibulum to beds on either side on anterior pituitary
hemodynamics
factors affecting blood flow
blood flow
volume of blood that flows through any tissue in a given period of time (mL/min)
cardiac output (CO) equation
CO is total blood flow
= heart rate x stroke volume
or
mean arterial pressure/resustance
pressure
force per unit surface area created by blood pushing against vessel walls
mean arterial pressure
the driving pressure of blood flow
- pressure from one end of the tube to the other end of the tube
flow
the volume of blood moving through (in mL/min)
aka CO
resistance
opposing force to the normal flow of blood
pulsatile flow
“spurts of blood” that happens when blood is ejected from the heart due to alternations of systole and diastole
- only in arteries, pressure drops by the time blood gets to capillaries, veins do not have pulsatile flow
where does the greatest drop in pressure occur?
in the arterioles before blood reaches the capillaries
laminar flow
silent, streamlined flow
- outermost layer moves slowest because of friction while the innermost moves fastest
turbulent flow
not laminar flow
- when fluid passes a constriction, sharp turn or rough surface
- swirling is partially responsible for heart sounds
taking blood pressure explanation
taken from brachial artery
- cuff flattens brachial artery so there’s no blood flow and no sound
- during systole, flow begins and the artery begins to opens as pressure in the cuff is released. the opening of the vessel creates the first sound and the pressure is about 120 mmHg
- at this point we hear the Korotkoff sounds as blood flow is turbulent (woosh)
- during diastole, blood vessel starts to open and in systole, blood vessel is nearly completely opened, sound disappears and pressure is about 80mmHg
importance of diastolic pressure
important because this is the pressure in the arteries that the heart needs to overcome to eject blood from the ventricles and can indicate risk of a cardiac event in young adults
velocity of blood flow
- velocity is inversely proportional to the cross sectional area of blood vessels
- at capillary beds, the cross sectional area increases quite a lot and this slows the blood down
pulmonary circulation
from right ventricle into pulmonary trunk
pulmonary trunk divides into L and R pulmonary arteries
2 pulmonary veins exit each lung and enter left atrium
aorta
exits left ventricle and divides into 3 parts:
- ascending aorta
- aortic arch
- descending aorta
ascending aorta
right and left coronary arteries branch from here
aortic arch
arches posterior and to the left, has 3 branches that supply the head, neck and upper limbs:
- brachiocephalic artery
- left common carotid artery
- left subclavian artery
descending aorta
includes:
thoracic aorta and abdominal aorta
thoracic aorta
region aboce diaphragm that supplies portions of the thoracic cavity (all but lung tissue)
abdominal aorta
region inferior to diaphragm, ends at the 2 common iliac arteries that lead to lower limbs
what is a STEMI
ST Elevated Myocardial Infarction
- ST segments are elevated above baseline because of blockage (usually in widowmaker coronary artery/anterior interventricular branch) which results in necrosis
- this causes an imbalance of ions here and thus causes the ECG tracing to be different
treatment of a STEMI
- inserting a stent: a mesh cage that holds the shape of a blood vessel
- bypass surgery: taking a vessel from a branch of artery just off the aorta and using it to supply that area of the heart; alternatively, can take a vein from the leg and attach it in to reroute the blood supply to the area (insert backwards because of valves present in veins)
drugs used to treat STEMI
- beta blockers: decrease HR and CO which decreases BP and makes heart beat more slowly
- calcium channel blockers: interrupts movement of Ca2+ into cells of the heart and blood vessels, making it so that the heart doesn’t have to work as hard
angina
symptoms of a heart attack caused by partial blockage of artery, but doesn’t cause death of the tissue
what does baby aspirin do?
thins blood, allowing it to more more easily through the heart which is why they suggest giving it to someone who you suspect has had a heart attack
