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CIRCULATORY SYSTEM - Coggle Diagram
CIRCULATORY SYSTEM
PRIMARY FUNCTIONS OF CIRCULATORY SYSTEM
- Transport necessary materials to cells
- Transport waste products away from cells to be released into environment
3 TYPES OF CIRCULATION
1. GASTROVASCULAR
2. OPEN CIRCULATORY - anthropods, mollusks
3. CLOSED CIRCULATORY
OPEN CIRCULATORY SYSTEMS
- contain fluid (hemolymph)
- pumped by 1 or more hearts
- through vessels that open into body cavity (hemocoel)
- diffusion exchanges nutrients and wastes
CLOSED CIRCULATORY SYSTEMS
- Blood and interstitial fluid are physically separated (components and composition)
- blood under pressure by 1 or more contractile muscular hearts
- blood remains within vessels
- capacity to heal themselves when wounded (clots)
ADVANTAGES
- animal can grow larger with more efficient supply
- Blood flow selectively controlled
SINGLE CIRCULATION
- single atrium collects blood from tissues
- single ventricle pumps blood out of heart
- arteries carry blood away from heart to gills
- oxygen picked up and CO2 dropped off, then blood delivers oxygen and nutrients to cells and collects wastes
- partially deoxygenised blood is returned to heart by veins
- heart doesn't generate high pressure, limits rate oxygenated blood can be delivered
DOUBLE CIRCULATION
- ocygenated and deoxygenated blood kept separate
- heart has 2 sets of atria and ventricles with one way valves
- pulmonary circuit ( to the lungs and heart)
- systemic circuit (blood to the body and deoxygenated to the heart)
- two different blood pressures (higher in arteries than veins)
ADAPTIVE FUNCTIONS OF CLOSED CIRCULATORY SYSTEMS
- adapts to changing conditions (sleep, activity, emergencies)
EXERCISE
- blood must be routed to different areas in proportion to their need for oxygen and nutrients
- controlled by Vaso dilation/constriction
- Cardiac output increases
- EPINEPHRINE: hormones from adrenal gland increases cardiac output (increases stroke volume/ heart rate)
- blood pressure increases a bit (blood vessels dilate, reducing resistance)
COMPONENTS OF CIRCULATORY SYSTMES
- fluid containing cells and solutes
- system of vessels, that're hallow tubes
- one or more muscular structures that pump fluid through vessels
COMPOSITION OF BLOOD
- plasma, RBC, WBC, platelets
- contain dissolved nutrients, proteins, gases and other molecules
MYOGENIC HEART
- generates own action potential
- MYOCYTES form interlocking networks with other myocytes to rapidly spread electrical current
- nervous input can increase or decrease rate
EXCITATION OF VERTEBRATE HEART
1. ATRIAL PHASE
- electrical signals generated at SA Node (pacemaker)
- modified myocytes with unstable resting membrane potential
- action potentials spread quickly through gap junctions
- both atria contract together forcing blood through AV valves into ventricles
2. VENTRICULAR PHASE
- Electrical impulses reach the AV Node
- conducts impulse from atria to ventricles
- both ventricles contract together
CARDIAC CYCLE
1. Diastole:
- ventricles relaxed and fill with blood coming from atria
- low blood pressure
2. Systole:
- ventricles contract and blood is pushed through semi-lunar valves
- high blood pressure
ELECTRO CARDIOGRAM (ECG/EKG):
- Records electrical impulses generated during cardiac cycle
- displays amplitude and direction of electrical signal
- examine for frequency, strength, duration and direction of signals
- monitors the electrical activity produced by SA node
- P WAVE: begins when SA node generates action potentials
- QRS COMPLEX: begins when branches from AV node excite ventricles
- T WAVE: repolarisation of ventricles back to resting state
BLOOD VESSELS
ARTERIES AND ARTERIOLES ARTERIES
- layers of smooth muscle and connective tissue around smooth endothelium
- blood away from heart
- walls contain elastin
ARTERIOLES
- Formed as artery branches become narrower
- can dilate/constrict to control blood distribution to tissues
BARORECEPTORS
- stretch receptors in certain arteries (aorta and carotid)
- communicate with brain to signal when BP is outside normal range
- brai/nerves can decrease/increase cardiac output/resistance as needed
CAPILLARIES
- site of gas and nutrient/waste exchange
- composition: endothelium resting on basal lamina
- narrowest vessels
1. CONTINUOUS CAPILLARIES smooth walls and small number of tiny openings
2. FENESTRATED CAPILLARIES numerous larger holes
MOVEMENT OF WATER IN AND OUT OF CAPILLARIES
- blood enters capillary under pressure
- pressure forces some water out through openings into interstitial fluid
- Most fluid leaves is recaptured and end of capillary
- pressure decreases along cap
- proteins in blood create osmotic force to draw fluid back into blood
VEINS AND VENULESVEINS
- blood back to heart
- thinner
- less muscular
- blood pressure lower
- smooth muscle contractions propel blood
- veins squeezed by skeletal muscles
VENULES
- Small
- thin extensions of capillaries
- if valves weren't present contractions of leg muscles would force blood in both directions
RELATIONSHIP WITH BLOOD PRESSURE, BLOOD FLOW AND RESISTANCE: - Blood pressure is responsible for blood flow - resistance is the tendency of blood vessels to slow down blood flow
MATHEMATICA; RELATIONSHIP - Poiseuille's law
Flow (F) = change in Pressure (P) divided by Resistance (R)
RESISTANCE TO FLOW
- R is function of vessel radius, length and blood viscosity
- change in arteriolar R is mechanism for controlling blood flow
- radius is most important
- vasodilation increases radius
- vasoconstriction decreased radius
VASODILATORY FACTOR PRODUCED BY ENDOTHELIAL CELLS
- ACh causes vasodilation by relaxing smooth muscle in anteriolar walls
- ACh causes
- vasodilation in circular strips
- vasoconstriction in flat strips
- vasodilatory factor is nitric oxide (NO)
SYSTEMIC BLOOD PRESSURE
- CARDIAC OUTPUT (CO) is the amount of blood the heart pumps in litres per minute
- Flow refers to CO
- BP = CO x TPR
(TPR is the total peripheral resistance)
CARDIAC OUTPUT
- CO depends on heart size, BPM, and how much blood it ejects
- stroke volume amount of blood heart ejects at each beat
TOTAL PERIPHERAL RESISTANCE
- greater cardiac and resistance, higher blood pressure
- arterial blood pressure is function of
- CO
- how constricted/dilated of various arterioles
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