Circulatory System Flashcards
(110 cards)
1
Q
Three components of a circulatory system
A
1) pump 2) system of tubes, channels, or spaces 3) fluid that circulates
2
Q
Three types of pumps
A
1) chambered hearts 2) skeletal muscle 3) pulsating blood vessels/peristalsis
3
Q
Interstitial fluid
A
Extracellular fluid that directly bathes tissues
4
Q
Blood
A
Fluid that circulates within vessels of closed circulatory system
5
Q
Lymph
A
Fluid that circulates in a secondary system in vertebrates, called the lymphatic system
6
Q
Hemolymph
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Fluid that circulates in an open circulatory system
7
Q
Three main components of vertebrate blood
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1) plasma 2) erythrocytes/red blood cells 3) other blood cells and clotting cells (leukocytes and thrombocytes/platelets_
8
Q
Hematocrit
A
Part of blood made up of erythrocytes
9
Q
Albumin
A
Vertebrate carrier protein in blood
10
Q
Globulins
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Vertebrate carrier protein in blood
11
Q
Thrombin
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Vertebrate blood clotting protein
12
Q
Fibrinogen
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Vertebrate blood clotting protein
13
Q
Hemoglobin
A
Respiratory pigment whose major function is storing and transporting oxygen
14
Q
Mechanism that sponges and flatworms use to circulate fluids in the body
A
Ciliated cells move water within body cavity
15
Q
Mechanism that cnidarians use to circulate fluids in the body
A
Muscular contractions of the body wall pump water in and out of body cavity
16
Q
Circulatory system of annelids
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Open (ex. tube worms) and closed (ex. earthworm)
17
Q
Circulatory system of molluscs
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Open (most) and closed (cephalopods) but all have hearts and some blood vessels
18
Q
Circulatory system of arthropods - crustaceans
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Open; small sinuses function as vessels and there is some control over distribution of hemolymph flow inside body
19
Q
Circulatory system of arthropods - insects
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Open; multiple contractile “hearts” along dorsal vessel and a tracheal system for most gas transport
20
Q
Circulatory tract of vertebrates
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Heart -> arteries -> arterioles -> capillaries -> venules -> veins -> heart
21
Q
Function of capillaries
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Diffusion of molecules between blood and interstitial fluids
22
Q
Tunica extrema
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Outer layer of vessels made of collagen
23
Q
Tunica media
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Middle layer of vessels made of smooth muscle and elastic connective tissue
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Q
Tunica intima
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Inner layer vessels before endothelium made of a smooth sheet of endothelial cells
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Endothelium
Most inner layer of vessels
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Veins consist of...
Tunica externa, media, and intima, then endothelium
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Venules consist of...
Tunica externa, then endothelium
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Capillaries consist of...
Endothelium
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Arteries consist of...
Tunica externa, media, and intima, then endothelium
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Arterioles consist of...
Tunica media, then endothelium
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Three types of capillaries
Continuous, fenestrated, and sinusoidal
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Continuous capillaries
Cells are held together by tight junctions (ex. skin, muscle, CNS blood brain barrier)
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Fenestrated capillaries
Cells contain pores; specialized for exchange (ex. kidneys, endocrine organs and intestines)
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Sinusoidal capillaries
A few tight junctions but are the most porous for exchange of large proteins (ex. liver and bone marrow)
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Circulatory pattern of water-breathing fish
Single circuit (heart --> gills --> body --> heart)
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Circulatory pattern of air breathing tetrapods (amphibians, reptiles, birds, mammals)
Two circuits: pulmonary circuit (right side of heart) and systemic circuit (left side of heart)
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Amphibian and reptile heart structure
Only partially divided, with two atria and one ventricle
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Cardiac cycle phases
1) systole/contraction - blood forced into circulation 2) diastole/relaxation - blood enters the heart
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Arthropod heart
Heart pumps out hemolymph via arteries
Blood returns via ostia (holes) during diastole
Valves in ostia open and close to regulate flow
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Mechanism of placement and control in arthropod hearts
Heart is suspended with a series of ligaments and is neurogenic/contracts in response to signals from nervous system
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Mammalian myocardium: compact or spongy
Compact
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Fish myocardium: compact or spongy
Spongy
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Four main parts of vertebrate heart walls
1) pericardium
2) epicardium
3) myocardium
4) endocardium
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Pericardium
Sac of connective tissue which surrounds heart; space between outer/parietal layer and inner/visceral layers is filled with lubricating fluid
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Epicardium
Outer layer of heart which is continuous with visceral pericardium; contains nerves that regulate heart and coronary arteries
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Myocardium
Layer of heart muscles/cardiomyocytes
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Endocardium
Innermost layer connective tissue covered with epithelial cells called the endothelium
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Compact myocardium
Tightly packed cells arranged in regular patterns
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Spongy myocardium
Meshwork of loosely connected cells
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Chambers of fish hearts
1) sinus venosus 2) atrium 3) ventricle 4) bulbus arteriosus
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Function of noncontractile bulbus in fish
Serves as volume and pressure reservoir
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Chambers of amphibian hearts
Two atria, one ventricle
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Function of trabeculae in amphibian ventricles
Helps prevent mixing of oxygenated and deoxygenated blood in ventricle
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Function of spiral fold in conus arteriosus in amphibian hearts
Helps direct deoxygenated blood to pulmocutaneous circuit and oxygenated blood to systemic circuit
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Chambers of reptile hearts
Two atria, three interconnected ventricular compartments, cavum venosum, cavum pulmonale, cavum arteriosum
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Function of cavum venosum in reptiles
Leads to systemic aortas
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Function of cavum pulmonale in reptiles
Leads to pulmonary artery
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Right to left shunt in reptile hearts
Deoxygenated blood bypasses pulmonary circuit and enters systemic circuit; used during breath-holding
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Left to right shunt in reptile hearts
Oxygenated blood reenters pulmonary circuit; aids oxygen delivery to myocardium in right heart
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Chambers of bird and mammal hearts
Two thin walled atria, two thick walled ventricles
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Intraventricular septum
Wall separating ventricles in birds and mammal hearts
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Valves in bird and mammals hearts
One tricuspid atrioventricular valve, one bicuspid/mitral atrioventricular valve, one aortic semilunar valve and one pulmonary semilunar valve
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Atriventricular (AV) valves
Found in birds and mammal hearts; between atria and ventricles
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Tricuspid valve
Right AV valve in mammal and bird hearts
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Bicuspid/mitral valve
Left AV valve in mammal and bird hearts
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Aortic semilnar valve
Between left ventricle and aorta in bird and mammal hearts
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Pulmonary semilunar valve
Between right ventricle and pulmonary artery in bird and mammal hearts
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MAP
Mean Arterial Pressure; average pressure in aorta over time (2/3 diastolic pressure + 1/3 systolic pressure)
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Diastole
Relaxation phase of cardiac cycle
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Systole
Contraction phase of cardiac cycle
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Definition of blood flow (Q)
Volume of fluid transferred per unit time
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Definition of blood velocity
Distance per unit time
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Formula for blood velocity
V = Q/A
| where V= velocity, Q = flow, and A = cross sectional area of the channels
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Law of bulk flow
Q = (change in P)/R where Q = flow, P = pressure drop, and R = resistance
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Myogenic
Cardiomyocytes produce spontaneous rhythmic depolarizations
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Gap junctions in cardiomyocytes
Gap junctions electrically couple cardimyocytes to ensure coordinated contractions. This means action potentials can pass directly from cell to cell
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Sinoatrial node
Pacemaker cells in vertebrates excluding fish
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Sinus venosus
Pacemaker cells in fish
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How do cardiomyocytes prevent tetanus?
Plateau phase that corresponds to refractory period and lasts as long as the cardiomyocyte contaction.
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Which channels cause the plateau phase of cardiomyocytes?
L-type Ca2+ channels
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Four channels on pacemaker cells
- Funny channels (Na+ influx)
- T-type Ca2+ influx channels
- L-type Ca2+ influx channels
- K+ channels (gradient controlled, but generally efflux)
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P-wave of ECG
Atrial depolarization; wave of depolarization from SA node throughout atria
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QRS complex of ECG
Ventricular depolarization
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T-wave of ECG
ventricular repolarization
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Function of modified cardiomyocytes
They do not contract, but rapidly spread action potential throughout myocardium. They can undergo rhythmic depolarizations.
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SA node function
Initiates electrical activity and spreads it to internodal pathways
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Internodal pathways function
Spreads electrical activity from SA node to AV node
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AV node function
Delays the signal from internodal pathways so that atria can contact, before signal moves onto Bundle of His and Purkinje fibres
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Bundle of His function
Spreading electrical signal from AV node down intraventricular septum
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Purkinje fibres function
Spreads electrical signal from Bundle of His through apex and upwards, causing ventricular contraction
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Formula for cardiac output
Cardiac Output = Heart rate x stroke volume
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Bradycardia
Decreased heart rate
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Tachycardia
Increased heart rate
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How is cardiac output modified?
Regulation of heart rate and/or stoke volume
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Frank-Starling effect
If end diastolic volume is low, sarcomere length is low and stroke volume is low. So, heart increases end diastolic volume to stretch muscles and increase length/tension of sarcomeres to optimum length for strong contraction and high stroke volume
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Autoregulation of stroke volume
Heart automatically regulates stroke volume by compensating for volume of blood returning to the heart
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Mean arterial pressure (MAP) formula
MAP = [cardiac output] x [total peripheral resistance]
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Myogenic autoregulation
Smooth muscles in arterioles contact in response to stretch from high BP; this causes them to act as negative feedback and stop excessive blood flow into tissues
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How do arterioles react to increased tissue metabolic activity?
Vasodilation to increase removal of CO2 and waste, and increase delivery of O2
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Effect of norepinephrine on arterioles
Vasoconstriction
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Effect of Vasopressin (ADH) on blood vessels
Vasoconstriction
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Effect of Angiotension II on blood vessels
Vasoconstriction
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Effects of atrial natriuretic peptide (ANP) on blood vessels
Vasodilation
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Source of norepinephrine
Sympathetic neurons
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Source of ADH
Posterior pituitary
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Cause of angiotension II release
Low blood pressure
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Cause of ANP release
High blood pressure
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How does body maintain nearly constant mean arterial pressure (MAP)?
By varying cardiac output (CO) and total peripheral resistance (TPR)
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Medulla oblongata
Cardiovascular control centre
110
Baroreceptors
Stretch-sensitive mechanoreceptors in walls of many major blood vessels that send signals to medulla and regulate MAP
