Ch. 25 - Circulation

Front 1

circulation

Back 1

- pressure driven bulk flow of blood through a system of tubular vessels or passages
- rapid transport of oxygen, carbon dioxide, nitrogenous wastes, hormones, immunoglobulins, heat, nutrients, ions

Front 2

pumps

Back 2

- peristaltic pump
- wave of contraction pushes blood

Front 3

muscular heart

Back 3

- single chambered
- may have accessory or auxiliary hearts
- multichambered

Front 4

open circulation for single chambered

Back 4

- blood baths tissue directly
- no clear distinction between blood and extracelluar tissue
- fluid = hemolymph
- blood exits discrete blood vessels
- enters lacunae = small spaces around tissues
- enter sinuses = large spaces used as channels for blood flow

Front 5

blood flow through lacunae and sinuses

Back 5

- aorta and lateral artery branches end abruptly
- slow rate of blood flow
- circulatory system can remain simple because tracheal system
- blood flows principally form posterior to anterior in dorsal part of body
- anterior to posterior in ventral part of body

Front 6

circulation through body or crayfish or lobster

Back 6

Front 7

closed circulation for single chambered

Back 7

Front 8

vertebrate circulation

Back 8

- single loop
- double loop

Front 9

circulatory plan in gill-breathing fish

Back 9

- heart pumps blood anteriorly into ventral aorta
- gives afferent branchial vessels to gill arches
- blood perfuses gills
- blood is collected into efferent branchial vessels which empty into dorsal aorta
- blood distributed to systemic tissues by dorsal aorta
- great veins return deoxygenated blood from systemic tissues to heart

Front 10

circulatory plan through human

Back 10

Front 11

teleost heart

Back 11

- myocardium usually spongy and oxygenated by blood in ventricle
- sinus venosus are great veins that empty into it
- ventricle is main propulsive force
- bulbus arteriosus acts as an elastic chamber and pressure reservoir

Front 12

amphibians

Back 12

- 2 separate atrial chambers
- ventricular trabeculas and spongy myocardium help shunt right atrial blood into pulmonary arteries
- conus arteriosus is contractile and has spiral folds which contribute to shunting
- double loop circulation

Front 13

truncus arteriosus

Back 13

- formed from conus arteriosus
- systemic arch goes to body
- pulmocutaneous arch goes to lungs and skin
- carotid arch goes to head region

Front 14

crocodiles

Back 14

- ventricle incompletely divided by muscular ridges and spongy septa
- 2 systemic aortas: one from right and left ventricle
- formen of panizza prevents left systemic arch from carrying deoxygenated blood

Front 15

blood flow in ventricles and atrium of crocodiles

Back 15

- cog valve is constricted and dilated by muscle action
- foreman diameter can be actively regulated
- when blood flows to lungs
- pressure in right ventricle stays too low to push open the flap valve into systemic aorta
- lung resistance rises and/or cog valves closes
- pressure in right ventricle rises high enough to eject blood into systemic aorta

Front 16

vertebrate heart

Back 16

- anterior vena cava = superior vena cava
- posterior vena cava = inferior vena cava

Front 17

chordae tendinae

Back 17

- thread-like bands of fibrous tissue
- attach one end to tricuspid and mitral valves and the other end to papillary muscle
- serve to anchor the valves

Front 18

papillary muscle

Back 18

- originate in ventricule wall
- small muscle within heart
- anchor heart valves
- attach to tricuspid valve by chordae tendinae

Front 19

heart valves

Back 19

- pulmonary valve
- tricuspid valve
- aortic valve
- mitral valve

Front 20

heart contraction and relaxation

Back 20

- systole is period of contraction
- diastole is period of rest/relaxation
- atrial and ventricular diastole
- atrial systole and ventricular diastole
- ventricular systole and atrial diastole

Front 21

human heart

Back 21

- oxygenated blood travels to heat in pulmonary veins and enters left atrium
- blood flows through left atrioventricular valve to enter left ventricle
- strongly muscular left ventricle pumps oxygenated blood through aortic valve into systemic aorta
- slows to entire systemic circuit
- after passing through systemic circuit, blood is partly deoxygenated
- flows into venae cavae, then into right atrium
- blood flows through right atrioventricular valve to enter right ventricle
- right ventricle pumps deoxygenated blood through pulmonary valve into pulmonary trunk
- flows to lungs in pulmonary circuit

Front 22

heart rate

Back 22

- pacemaker generates wave of signals to contract
- signals are delayed at AV node
- signals pass to heart apex
- signals spread throughout ventricles

Front 23

pacemaker action potential

Back 23

- pacemaker cells are special myocardial cells that discharge rhythmically
- have special type of action potential
- first part of prepotential is caused by relatively smaller efflux of K+ in phase 4 of action potential
- transient type of calcium channel (T) opens
- form second part of prepotential
- as potential declines, the long lasting calcium channel opens
- leads to depolarization
- mostly due to Ca2+ with only little influence from Na+ influx
- absence of sharp depolarizing spike

Front 24

cardiac action potential

Back 24

- sodium enters the cell through fast Na channels
- fast Na channels close
- Ca and additional Na enter cell through slow channels
- K exits cell and resting membrane potential is reestablished
- equilibration of Na and K occurs

Front 25

conducting system

Back 25

- depolarization begins in SA node and spreads outward through atrial muscle
- spreads into AV node is delayed
- depolarized atria starts to contract
- once AV becomes depolarized, depolarization spreads rapidly into ventricles along conducting system
- atrial muscle starts to repolarize
- nearly simultaneous depolarization of cells throughout ventricular myocardium leads to forceful ventricular contraction

Front 26

human electrocardiogram

Back 26

Front 27

heart as a pump

Back 27

- cardiac output is volume of blood per unit time
- vertebrate cardiac output is volume of blood in left ventricle to systemic circulation
- product of heart rates in beats per minute
- stroke volume is volume of blood pumped per cardiac cycle

Front 28

anatomy of blood vessels

Back 28

- arteries carry blood away from heart
- veins carry blood back to heart
- capillaries connect smallest arteries to veins

Front 29

layers of muscular artery

Back 29

- tunica intima
- tunica media
- tunica externa/adventitia

Front 30

tunica intima

Back 30

- simple squamous endothelium
- overly basement membrane
- layer of fibrous tissue

Front 31

tunica media

Back 31

- usually thickest
- smooth muscle
- collagen
- some elastic

Front 32

tunica externa/adventitia

Back 32

- loose connective tissue with vasa vasorum

Front 33

large artery

Back 33

- conducting or elastic arteries
- internal elastic lamina
- expand during systole and recoil during diastole
- collagenous tissue
- aorta, common carotid, subclavian, pulmonary trunk, common illeac

Front 34

medium artery

Back 34

- muscular or distributing arteries
- brachial, femoral, renal
- internal and external elastic lamina

Front 35

arteriole

Back 35

- resistance arteries
- smallest of these are arterioles
- smooth muscles in walls are responsible for vasomotor control of blood distribution
- vasoconstriction and vasodilation

Front 36

arteries

Back 36

- become smaller in diameter
- walls become thinner
- very little drop in pressure in arterial system
- circumferential tension (stretch) developed within walls is directly proportional to tube radius
- small artery exposed to same blood pressure as larger one
- tension developed in walls is lower in large one because radius is smaller
- smaller artery can be less fortified than a larger one and not over-expand

Front 37

microcirculatory bed

Back 37

- arteriolar-venular anastomoses are direct connection between arterioles and venules
- when open provide way for blood to bypass capillary bed
- precapillary sphincters composed of rings of smooth muscle cells that act as muscular valves
- blood enters through arteriole at rate determined by arteriole radius
- controlled by smooth muscle cells in arteriole wall
- blood leaves through venule

Front 38

sphincters

Back 38

- smooth muscles and precapillary sphincters permit highly sensitive temporal and spatial control of blood distribution
- change blood pressure and blood flow

Front 39

fenestrated capillary

Back 39

- only endothelium
- filtration holes
- contain channels
- discontinuous and continuous cells
- important in kidneys, endocrine glands, smal intestines, choroid plexus of brain

Front 40

continuous capillary

Back 40

- endothelial cells held together by tight junctions
- may have pericytes that contract to regulate blood flow

Front 41

sinusoidal capillary

Back 41

- discontinuous capillaries
- irregular blood filled spaces
- liver, bone marrow, spleen
- blood forming organs
- huge sinus
- diffusion through cell
- thicker epithelium

Front 42

circulatory routes

Back 42

- simplest pathway = one capillary bed
- portal system
- arteriovenous anastomosis

Front 43

portal system

Back 43

- 1 capillary system to next capillary system
- hypothalamus and anterior pituitary
- small intestine and liver
- kidney

Front 44

arteriovenous anastomosis

Back 44

- can pass through capillary bed, around capillary bed, or combination of both
- embryonic
- shunt

Front 45

capillary exchange

Back 45

- only occurs across capillary walls between blood and surrounding tissues
- 3 routes across endothelial cells
- intracellular clefts
- fenestrations
- cytoplasm or transcytosis

Front 46

diffusion

Back 46

- most important mechanism of capillary exchange
- movement of material through OM
- high concentration to low concentration
- lipid soluble substances = steroid hormones
- O2 and CO2 diffuse easily
- insoluble substances
- glucose and electrolytes must pass through channels, fenestrations, or intracellular clefts
- large particles such as proteins are held back

Front 47

transcytosis

Back 47

- endothelial cells pick up material on one side of PM by pinocytosis or receptor mediated endocytosis
- transport it through cell to other side where it exits by exocytosis
- mediated by endocytosis and exocytosis
- enters one cellular face and leaves through another
- tissues to blood or blood to tissue
- large proteins and small peptides

Front 48

filtration

Back 48

- hydrostatic pressure forces fluid through a selectively permeable membrane
- driven by pressure differences
- capillaries give off fluid at arteriole end due to higher BP/hydrostatic pressure
- hydrostatic and osmotic pressure decrease along length of capillary
- create collodial pressure that's greater than outside pressure
- collodial osmotic pressure higher at venule end forces fluid back in (reabsorption)
- net filtration pressure is difference between outward and inward pressure

Front 49

blood plasma volume

Back 49

- loses volume in initial segment of blood capillaries
- regain fluid in final segments
- lose at arteriole and gain at venous
- hydrostatic pressure of blood pushes stuff out
- hydrostatic pressure of tissue and collodial osmotic pressure bring stuff in

Front 50

net filtration pressure

Back 50

- hydrostatic pressure of blood in capillaries
-minus hydrostatic pressure of tissue fluid outside capillaries
- plus collodial osmotic pressure of blood

Front 51

veins

Back 51

- lower blood pressure with fluctuation
- thinner walls
- less muscular and elastic tissue
- expand easily
- high capacitance
- valves aid skeletal muscles in upward blood flow

Front 52

venous sinuses

Back 52

- veins with thin walls
- large lumens
- no smooth muscle

Front 53

large vein

Back 53

- venae cavae, pulmonary veins, internal jugular, renal veins

Front 54

medium vein

Back 54

- many have valves
- infoldings of tunica interna
- skeletal muscle pump pushes blood through valve toward heart
- prevents backflow

Front 55

venule

Back 55

- post capillary
- surrounded by pericytes
- porous
- exchange fluid with surrounding tissue

Front 56

mechanism of venous return

Back 56

- pressure gradient
- gravity drains blood from head and neck
- skeletal muscle pump in the limbs = pushes blood back
- thoracic has negative pressure = draws blood up
- cardiac suction of expanding atrial space = sucks blood up

Front 57

venous return

Back 57

- valves in veins prevent backflow of blood
- skeletal muscles compress veins
- force blood towards heart

Front 58

blood distribution

Back 58

- majority in veins

Front 59

cross sectional area and capillaries

Back 59

- as blood flows from aorta to capillaries
- total cross sectional area increases
- average linear velocity decreases
- greatest cross sectional area in capillaries
- cross sectional area increases, velocity decreases
- velocity slowed down due to decreased pressure
- pressure decreases from arteries to veins
- never return to original velocity
- greatest velocity in arteries

Front 60

hematocrit

Back 60

- 43% erythrocytes (RBC)
- thin layer of leukocytes called buffy coat between erythrocytes and plasma

Front 61

red blood cells

Back 61

- erythrocytes
- 7-7.4 um
- biconcave
- increased surface area

Front 62

reticulocyte

Back 62

- immature RBC
- everyone has certain number
- carry almost as much oxygen as normal RBC

Front 63

sickle cell anemia

Back 63

- abnormal RBC
- get stuck in capillaries
- heterozygous have some sickling
- homozygous have a lot of sickling

Front 64

rouleaux

Back 64

- RBC done't settle very much
- some disease conditions increase production of fibrinogen and immunoglobulins causing RBC to clump
- ERS used to follow progress of certain disease conditions

Front 65

2 classes of leuckocytes

Back 65

- granulocytes
- a granulocytes

Front 66

granulocytes

Back 66

- have granules
- neutrophils
- eosinophils
- basophils

Front 67

a granulocytes

Back 67

- azurophilic granules
- some granules but very little
- lymphocytes
- monocytes

Front 68

neutrophils

Back 68

- larger than RBC
- one nucleus and variable number of lobes
- squeeze out of blood into tissue
- diaponeses is process of squeezing into tissue

Front 69

basophils

Back 69

- numerous granules cover nucleus
- release histamines
- deal with inflammatory response
- larger than RBC

Front 70

eosinophils

Back 70

- found in high numbers
- allergic reaction and parasitic infection
- larger than RBC

Front 71

monocyte

Back 71

- large kidney shaped nucleus
- cytoplasm slightly basophilic
- located in blood
- called macrophage in located outside blood
- phagocytic
- antigen presenting cell

Front 72

lymphocyte

Back 72

- killer cells, B and T cells
- antibody production = B cells
- mediated cell response = T cells
- specific protein receptors on cell surface

Front 73

platelets

Back 73

- derived from megakarocytes in bone marrow
- multi nucleated cells
- live in bone marrow
- fragments of cell
- contain growth factors and clotting factors

Front 74

blood cell production

Back 74

- controlled by cytokines
- almost all glycoprotins that act of stem cells

Front 75

3 factors of cytokines affect blood cell production

Back 75

- colony stimulating factors (CSF)
- erythropoietin
- interleukins

Front 76

colony stimulating factors (CSF)

Back 76

- made by endothelial cells and white blood cells

Front 77

erythropoietin

Back 77

- lack of oxygen or shortage of erythrocytes
- stimulates cells in kidney to synthesize and secrete hormone

Front 78

interleukins

Back 78

- made by lymphocytes
- serve as growth factor for B cells
- non-lymphocytes blood cells

Front 79

total fluid energy

Back 79

- true driving force for blood flow
- potential energy of pressure produced by heart
- plus kinetic energy
- plus kinetic energy of position in earth's gravitational field

Front 80

pressure change

Back 80

- important driving force
- around 100
- affects rate of blood flow
- above heart = arterial pressure decreases
- below heart = arterial pressure increases

Front 81

flow rate

Back 81

- dependent on differences in blood pressure and vascular resistance
- poiseuille equation
- proportional to pressure difference
- proportional to fourth power of radius
- inversely proportional to resistance
- inversely proportional to viscosity
- inversely proportional to length

Front 82

principles of blood flow

Back 82

- blood flow is amount of blood flowing through a tissue in given time
- perfusion is rate of blood flow per given mass of tissue
- blood flow and perfusion important for delivery nutrients and oxygen, and removal of waste
- hemodynamics are physical principles of blood flow based on pressure and resistance

Front 83

change in radius

Back 83

- muscles in walls of blood vessels change radius of vessel by contracting or relaxing
- exert profound control over flow rate

Front 84

heat

Back 84

- pressure and flow turn to heat during circulation

Front 85

velocity profile of laminar flow

Back 85

- velocity immediately next to tube wall are zero
- steady and non-turbulent flow, liquid moves in series of concentric layers that differ in linear velocity
- layers closer to center move faster

Front 86

frictional force

Back 86

- concentric layers encounter as they flow over each other
- total magnitude of internal friction depends in part on diameter and length
- viscosity also contributes to internal frictional force
- lack of intrinsic slipperiness between liquid layers moving at different velocities

Front 87

radius affects velocity

Back 87

- large radius = high average velocity
- small radius = slower average velocity
- slowed down by friction against vessel wall

Front 88

energy to heat

Back 88

- results in degradation of kinetic energy into heat
- pressure provided at entry end of heart is potential energy
- converted to kinetic energy
- kinetic energy converted to heat energy
- pressure converted to heat

Front 89

blood pressure

Back 89

- dependent on elasticity of arteries
- expansion and recoil maintain steady flow of blood throughout cardiac cycle
- smoothes out pressure fluctuations and decrease stress on small arteries
- rises with age because arteries less distensible (elastic)
- produce fewer elastic fibers as you age

Front 90

blood pressure determinants

Back 90

- cardiac output = volume of blood pumped by heart
- blood volume
- peripheral resistance = mean arterial pressure minus venous pressure divided by cardiac output

Front 91

mean arterial pressure

Back 91

- diastole last longer than systole
- equals diastolic plus (systolic - diastolic)

Front 92

cardiac output

Back 92

Front 93

starling's law

Back 93

- energy of contraction is proportional to initial length of cardiac fiber
- length of cardiac fiber is increased with increased filling
- when cardiac muscle is stretched it contracts more forcefully
- optimum overlap creates greatest contraction

Front 94

skeletal vs heart muscle

Back 94

- both have developed forces rise to peak at optimal length then then fall off at very long lengths
- declining portion in both is due to diminishing overlap between actin and myosin
- at lengths less than optimal, force declines because myosin collision with z line and Ca release from SR declines with short lengths
- resting force higher in cardiac and significant at lengths less than optimal
- intact heart can respond to increase of filling by improving contraction

Front 95

total peripheral resistance

Back 95

Front 96

regulation of BP and flow

Back 96

- local control
- neural control
- hormonal control

Front 97

local control

Back 97

- ability of tissue to regulate its own blood supply
- when tissue inadequately perfused = becomes hypoxic and metabolites accumulate
- metabolites are CO2, H+, K+, lactic acid, adenosine
- factors stimulate vasodilation
- short term stimulate by vasoactive chemicals like histamine and nitric acid
- derived from platelets, endothelial cells, perivascular tissue
- long term achieved by growth of new vessels

Front 98

neural control

Back 98

- control in vasomotor control center of medulla
- integrate baroreflexes, chemoreflexes, and medullary ischemic reflex
- change in blood pressure
- chemoreflexes monitor pH, O2, and CO2 levels
- issue signals to blood vessels through sympathetic nerve fibers
- medullary ischemic reflex responds to drop in perfusion by increasing heart rate and contraction force

Front 99

hormonal control

Back 99

- regulated by various hormones like
- angiotensin 2 = vasoconstrictor
- aldosterone = promotes Na+, water retention by kidney that increases BP
- atrial natiuretic peptide = increases Na+ excretion by kidney that lowers BP
- ADH = promotes water retention
- epinephrine and norepinephrine = bind to smooth muscle of blood vessels causing vasoconstriction

Front 100

vasomotion

Back 100

- generalized raising or lowering of BP
- selectively modifying perfusion of particular organ
- rate of oxygen delivery = cardiac output x ([arterial O2] - [venous O2])

Front 101

exercise

Back 101

- cardiac output increased by both heart rate and stroke volume
- cardiac rate result of vagus nerve inhibition and sympathetic nerve stimulation
- coordinated by cardiac centers in medulla
- arterial blood pressure doesn't rise because vascular resistance reduced by vasodilation
- arterioles shift blood flow with changing priorities
- increase perfusion of lungs, myocardium, and skeletal muscles
- decreases perfusion of kidneys and digestive tract