Nature of Science theories are regarded as uncertain William Harvey overturned theories developed by the ancient Greek philosopher Galen on movement of blood in the body Galen 130 200 Greek physician amp philosopher ID: 247470
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Slide1
6.2 The blood system
REVIEW! Slide2
Nature of Science
: theories are regarded as uncertain:
William Harvey overturned theories developed by the ancient Greek philosopher Galen on movement of blood in the body.
Galen (130- 200) – Greek physician & philosopherPerformed many dissections & studied muscles, spinal cord, heart, urinary system, & proved that the arteries are full of blood believed that blood originated in the liver, and sloshed back and forth through the body, passing through the heart, where it was mixed with air, by pores in the septumIntroduced the spirit system, consisting of natural spirit or "pneuma" (air he thought was found in the veins), vital spirit (blood mixed with air he believed to found in the arteries), and animal spirit (which he believed to be found in the nervous system).This was not overturned until 1650 by William Harvey – 1400 years!Slide3
William Harvey
Lived
1578 to 1657
.First to correctly describe blood’s circulation in the body. (For 1400 years, Galen’s beliefs accepted without evidence!)Harvey showed that arteries and veins form a complete circuit that starts and leads back to the heart.The heart’s contractions drive the flow of blood around the whole body.Predicted existence of capillaries linking arteries and veins (no lenses powerful enough to see them then).Slide4
Harvey
“I
have often wondered and even laughed at those who fancied that everything had been so consummately and absolutely investigated by an Aristotle or a Galen or some other mighty name, that nothing could by any possibility be added to their knowledge.”
-WILLIAM HARVEYSlide5
Skills
:
Recognition of chambers & valves of heart & blood vessels connected to it in diagrams or dissected hearts.
How many chambers? How many valves?Right side’s job?Left side’s job?Which side has O2-rich blood?Which side has O2-poor blood?Slide6
Important
h
eart structure facts!
4 chambers2 atria2 ventricles4 valves2 atrioventricularTricuspid & bicuspid (mitral)2 semilunarPulmonary & aorticPulmonary circulation = blood pumped to LUNGS (from right side of heart)Systemic circulation = blood pumped to body systems (from left side of heart)
Right side
= deoxygenated (O2-poor blood)
Left side
= oxygenated (O2-rich blood)
Septum
= muscle wall separating right and left sides of heart
Apex
= bottom point of heart
Chordae
tendonae
= “heart strings” – tendons that support the valvesSlide7Practice drawing:Slide8
… just kidding! Use this one:Slide9Simplified diagram of heart:Slide10Cross-section of ventriclesSlide11Cross-section of ventriclesSlide12
Skills
:
Identification of blood vessels as arteries, capillaries or veins from structure of their walls.Slide13Transverse section (drawing)Slide14Transverse section (micrograph)Slide15Transverse section (micrograph)Slide16
Now YOU try! Drawing MicrographSlide17
Understanding
:
Arteries convey blood at high pressure from the ventricles to the tissues of the body.
Ventricles = main pumping chambers- thick wallsArtery = transports blood AWAY from heart (to tissues/cells) – thick wallsElastic & muscle layers control blood flow & make walls toughElastin fibers store energy that stretches with each pumping cycleSmooth muscle contraction determines diameter of lumen
Aneurysm
= bulging of artery due to high pressure
Pulse
= heart rate
Major arteries:
Renal artery
kidney
Hepatic artery liver
Coronary artery heartSlide18
Taking your pulsehttp://www.madsci.org/experiments/archive/857361537.Bi.html
RADIAL artery CAROTID arterySlide19
4 types of tissue(need to know this for next slide)Slide20
Understanding
:
Arteries have muscle and elastic fibers in their walls
3 layers of artery wall:Tunica externa (adventitia) = tough; collagen, elastin, fibroblasts (connective)Tunica media = thick; smooth muscle & elastic fibers made of “elastin”(connective)
Tunica intima
(
interna
) = smooth endothelium (
epithelial
)Slide21
Understanding
:
The muscle & elastic fibers assist in maintaining BP between pump cycles
Systolic pressure = highest pressure reached in an artery because heart is contracting (pushes wall out; stretches elastic fibers)Diastolic pressure = lowest pressure reached in artery because heart is relaxing (stretched elastic fibers squeeze blood in lumen)
BP = systolic/diastolicSlide22
Vasoconstriction
Vasoconstriction
= circular muscles in artery contractNarrows lumenIncreases
bp because restricts blood flowVasodilation = circular muscles in artery relax Increases lumenDecreases bp because increases blood flowArterioles
= smaller branches of major arteries
Hormones
&
nerve
impulses control blood flowSlide23Slide24
Understanding:
Blood flows through tissues in capillaries with permeable walls that allow exchange of materials between cells & blood
Capillaries
= narrowest blood vessels (diameter = 10 µm)Branch & rejoinTransport blood through almost all tissues (cornea & lens are exceptions)How do cornea & lens receive oxygen?One layer of thin endothelium cells Very permeable allows some plasma to leak & form “tissue fluid”Tissue fluid
= water, oxygen, glucose (not large proteins) allows cells to take these substances in & excrete waste products then fluid re-enters capillariesSlide25
Cruisin’ for a Bruisin
’
(bruise = “contusion”)
Damage to capillaries & leakage of blood into spaces between cells Capillaries quickly repairHemoglobin broken down to green & yellow bile pigments & removedPhagocytes remove blood cells by endocytosis (going INTO the cells)Slide26
Understanding
:
Veins collect blood at low pressure from tissues & return it to ATRIA of heart
Veins transport blood TO the heartLower pressure than arteriesThinner wall; fewer muscle & elastic fibersDilate to become wider & hold more blood
80% of sedentary person’s blood in veins
Blood flows thru veins via
:
Gravity
Squeezing action of skeletal muscle
Major veins
:
A
rms
subclavian veins
heart
Head
jugular veins
heart
Stomach & intestines
hepatic portal vein
liver
hepatic vein
heartSlide27
Understanding
:
Valves in veins & heart ensure circulation by preventing backflow
Valves are needed to prevent backflow of blood because BP can get very lowValves cause blood to flow in one direction only Slide28
Leaky vein valvesSlide29
Understanding
:
There is a separate circulation for the lungs.
The heart is a double-pump!Pulmonary circulation = to & from LUNGS (under LOW pressure)2.
Systemic circulation
= to & from all other ORGAN SYSTEMS
(under higher pressure)Slide30
Application
:
http://www.webmd.com/lung/video/causes-symptoms-copdCauses & consequences of occlusion of the coronary arteries.“sclerosis” = hardeningE.g. Multiple sclerosis, arteriosclerosis, atherosclerosis
“
arterio
”
= arteries & arterioles
Arteriosclerosis = thickening & hardening of arteries
“
athero
”
= atheroma = fatty tissue
Atherosclerosis
= a type of arteriosclerosis where there is a buildup of fat & cholesterol (plaques) on artery walls, which can restrict blood flow
Involves attraction of phagocytes & smooth muscle cells forming cap over plaquePlaques can burst, triggering a blood clot
Consequences:
Coronary occlusion
= blockage of a blood vessel that supplies oxygen to heart
Can cause
anoxia
(lack of O2),
angina
(pain) &
myocardial infarction
(heart attack).
Correlations (possible causes)
:
High concentrations of
LDL
(low density lipoproteins)
Chronic high
blood glucose
(overeating, obesity, diabetes)Slide31
High vs Low Density Lipoproteins
Lipoproteins
are how fats move through bloodSlide32
Understanding:
The heartbeat is initiated by a group of specialized muscle cells in the right atrium called the sinoatrial node
Cardiac muscles are unique
they don’t need stimulation from motor neurons“myogenic” = heart contraction is generated in heart muscle itself = “of its own accordMembrane of heart muscle cell depolarizes when cell contracts, activating other cells to contractSinoatrial node = SA node = region in right atrium who’s cells have fastest rate of spontaneous beating (first to depolarize due to extensive membranes)Slide33
SA nodeSlide34
Understanding
:
The sinoatrial node acts as a pacemaker.
SA Node initiates each heartbeatSA Node = “pacemaker” = it sets the pace for the heartbeatArtificial pacemaker = replacement for natural pacemaker = electronic device under skin with electrodes implanted in heart wallSlide35
Understanding:
The SA node sends out electrical signal that stimulates contraction as it is propagated through the walls of the atria & then the walls of the ventricles
. https://
www.youtube.com/watch?v=RYZ4daFwMa8Slide36
Understanding:
The heart rate can be increased or decreased by impulses brought to heart thru 2 nerves from medulla oblongata
2 nerves that regulate heart rate
:Vagus nerve = decreases heart rate (parasympathetic nervous system)2. Sympathetic cardiac nerve = increases heart rate (sympathetic n.s.)Slide37
Understanding
:
Epinephrine increases the heart rate to prepare for vigorous physical activity.
2 nerves and a hormone regulate heart rate!Epinephrine = adrenalinProduced by adrenal gland (adrenal medulla = middle of adrenals)“fight or flight” hormoneSecretion controlled by brainIncreases heart rateSlide38
Heart Sounds
http
://depts.washington.edu/physdx/heart/demo.htmlSlide39
Application
: Pressure changes in the left atrium, left ventricle & aorta during the cardiac cycleSlide40
Cardiac cycle
Systole
= ventricles contracting
Diastole = ventricles relaxinghttp://highered.mheducation.com/sites/0072495855/student_view0/chapter22/animation__the_cardiac_cycle__quiz_2_.htmlhttp://www.springer.com/cda/content/document/cda_downloaddocument/4901s.swf?SGWID=0-0-45-754914-0Slide41
EKG (
ECG)
http://www.rnceus.com/ekg/ekghowto.html
EKG = electrocardiogram = electrical activity of heart beatkardia = “heart” in Greek