adaptions for transport: ANIMALS (C3) Flashcards
Open circulatory system
use insects to explain
OPEN:
-blood is under LOW pressure as NOT contained within vessels
- HEAMOLYMPHY leaves circulatory system it bathes organs directly
- fluid is pumped from LONG DORSAL (top) TUBULAR heart into spaces within body cavity (HEAMOCEOL)
- o2 reaches GE surface via TRACHEAL system , NO respiratory pigment needed to carry o2
- o2 is transported DIRECTLY to tissues
Closed circulatory system
CLOSED:
-blood is under HIGH pressure and CONTAINED within vessels e.g arteries, veins, capillaries
- NEVER directly contact organ
- o2 DIFFUSES into blood and carried bound to HAEMOGLOBIN (respiratory pigment)
- o2 is transported from LUNGS to HEART then towards CAPILLARIES in body TISSUES
Open CS example
insects
Closed CS example and explain the less common one
- mammals
- fish
-earthworms (has DORSAL and VENTRAL vessels running length of body, connected by 5 pairs of PSEUDOHEARTS)
Two types of closed CS with examples
SINGLE circulatory system e.g fish
(passes once)
DOUBLE circulatory system e.g mammals
(passes twice)
Two circuits in double circulation
PULMONARY (lungs) circulation:
blood vessels involved in transporting blood from heart to lungs
SYSTEMIC (body) circulation:
blood vessels involved in transporting blood from heart to rest of body/tissues (excluding lungs)
Advantages of double circulation (4)
- maintains a high pressure in the systemic (body) circulation
- ensuring o2 is delivered to respiring tissues more efficiently - allows for lower pressure in pulmonary (lung) circulation
- prevents build up of tissue fluid in lungs - rapid circulation in the systemic circuit
- efficiently move blood at a larger distance due to faster circulation - oxygenated and deoxygenated blood is kept separate
- maintains a steep concentration gradient for o2 and co2 at tissues and lungs
What transport system is used in mammals?
closed, double
3 types of blood vessels and movements
ARTERIES - transport blood AWAY from heart
VEINS - transport blood TO heart
CAPILLARIES - smallest vessels that allow EXCHANGE of substances with body cells
Layers of the blood vessels
- arteries and veins name 5
- capillaries name 1
arteries and veins: (have the same layers yet proportions differ) -tunica externa -tunica media -tunica intima -endothelium (one cell thick) -lumen
capillaries:
-endothelium (one cell thick)
Function of blood vessel layer structures
- endothelium
- elastic fibers and smooth muscle
- collagen fibers
ENDOTHELIUM: inner most layer, one cell thick, provides a smooth lining = reduces friction reducing resistance to blood flow / in capillaries being one cell thick provides short diffusion path
(1)SMOOTH MUSCLE AND (2)ELASTIC FIBERS: middle layer, (1) thick smooth muscle withstands high blood pressure produced by pumping action of heart, can contract and relax directing blood flow (2) stretch and recoil to maintain high blood pressure
COLLAGEN FIBERS: outer layer, resistance to over stretching
Structure of veins
lumen? walls? muscle layer?
WIDE diameter LUMENS - so can deliver large volumes of blood back to heart
THIN WALLS - pressure inside much lower as further distance from heart
THIN MUSCLE LAYER - can be compressed easily, contracting muscles can squeeze veins pushing blood upwards to heart
Structure of arteries
lumen? muscle/elastic layers?
NARROWED lumen -compared to veins
THICK SMOOTH MUSCLE LAYER - withstand high blood pressure
THICK ELASTIC FIBERS - for elastic recoil to maintain high blood pressure
Structure of capillaries
lumen? wall? features?
NARROW LUMEN - restricts blood flow, slowing blood to allow more time for exchange of materials at tissues
THIN WALL - short diffusion pathway (1 endothelium cell thick)
some capillaries are PERMEABLE to water and dissolved substances e.g glucose, amino acids, o2, co2
What and where are pocket valves?
in the VEINS ensuring that blood flows in ONE DIRECTION (towards the heart)
*maintaining UNIDIRECTIONAL flow of blood in the heart and veins
How do valves work?
- blood tries to flow back
- blood fills pocket above valve
- this forces valve shut
= preventing back flow
(veins in/above heart have no valves as gravity draws blood down toward the heart)
Blood pressure in blood vessels
ARTERIES: high pressure
VEINS: low pressure
CAPILLARIES: falls as velocity of blood decreases
Description of heart
- four chambers
- consists largely of cardiac muscle
- specialized tissue capable of rhythmic contraction and relaxion over a long period without fatigue
Four chambers of the heart, thickness and order
- right atrium
- right ventricle
- left atrium
- left ventricle
atriums are at the top of the heart, ventricles at the bottom (A is first in alphabet so at the top)
ventricles have thicker walls, than thinner walled atriums
Mammalian circulatory system
- double circulatory
- first circuit: pulmonary circulation
- second circuit: systematic circulation
Fuction of tendentious cords
- due to increased blood pressure from VENTRICLES contracting the atrial ventricular (AV) VALVES close simultaneously preventing BACK FLOW of blow into the ATRIA
- the TENDINOUS CORDS prevent valves inverting into atria
External structures of the heart
- CORONARY veins
- CORONARY arteries
- providing heart it’s own blood supply system
Function of coronary veins
remove DEOXYGENATED blood from the CARDIAC MUSCLE
Function of coronary artery
SUPPLY the HEART cells with OXYGENATED blood
- if these are blocked due to accumulation of fatty material then the heart becomes starved of blood and o2 ( CHD )
Describe blood flow through the heart
- deoxygenated blood enters heart through inferior/ superior vena cava
- enters right atrium
- right atrium contracts pushing blood through the the TRICUSPID valve into right ventricle
- right ventricle contracts pushing blood through the semi luna (pulmonary valve) into the pulmonary artery
- travels to the lungs ( dissociates co2, associates o2)
- oxygenated blood reruns through pulmonary veins enters the left atrium
- left atrium contracts pushing blood through BICUSPID valve into left ventricle
- left ventricle contacts pushing blood through semi luna/aortic valve into aorta (major artery)
- oxygenated blood leaves heart travels to body tissues
What is the cardiac cycle? And it’s three stages in continuous process
the sequence of events in the heartbeat
1) ATRIAL SYSTOLE
2) VENTRICLE SYSTOLE
3) DIASTOLE
Summaries the cardiac cycle
- right atrium receives deoxygenated blood from the vena cava and the left atrium receives oxygenated blood from the pulmonary vein
- both atria contract together and both ventricles contract together
- a single heartbeat is on single contraction (SYSTOLE) and relaxation (DIASTOLE)
When the tri and bi cuspid valves (AV valves) open and close?
…open when the atrial pressure is greater than the ventricular pressure
…and close when the ventricle pressure is greater than atrial pressure
When do the semi luna valves open and close?
…open when the pressure in the in the ventricles is greater than the aorta and pulmonary artery
…close when the pressure in the arteries is greater than the ventricles and blood tries to flow back
Blood pressure changes in the vessels: ARTERIES
- HIGHEST pressure occurs in the aorta/arteries CLOSEST to the heart
- there is a RHYTHMIC RISE and FALL corresponding to the VENTRICULAR contraction and relaxation
Blood pressure changes in the vessels: ARTERIOLES
- FRICTION with vessel walls causes a progressive DROP in pressure (friction slows blood down)
- NARROWED lumen increases RESISTANCE, decreasing blood flow and therefore DECREASING blood pressure
- pressure in arterioles depends on if they are DILATED (wider) thus a smaller decrease in blood pressure or CONSTRICTED (narrowed) thus a larger decrease in blood pressure
Blood pressure changes in the vessels: CAPILLARIES
- SMALL DIAMETER, therefore FRICTION with walls slowing the blood flow and decreasing pressure
- some fluid LEAVES the capillaries into tissues, further REDUCING blood flow as well as pressure
Blood pressure changes in the vessels: VEINS
- pressure in veins is LOW but DOSEN’T fall to ZERO due to the massaging effect of the SKELETAL MUSCLES
- return flow of blood to the heart is NON-RHYTHMIC as the veins are TOO FAR from the heart to be affected by systole and diastole
The heart has myogenic nature - what does this mean?
the heartbeat is initiated from within the muscle itself and is not due to external stimulation
Control of the heartbeat in stages (6)
- sino-atrial node (SAN) found in wall of right atrium acts as a PACEMAKER which sends a wave of DEPOLARISATION (electrical impulse) across the atria causing them to CONTRACT simultaneously
- electric stimulation is PREVENTED from spreading to the ventricles by a thin layer of connective TISSUE which acts as a layer of INSULATION
- electrical impulse reaches the atrio-ventricular node (AVN) lying between the two atria, passing impulse to the VENTRICLES
- from AVN impulse passes down the BUNDLE OF HIS to the APEX of the heart
- the PURKINJE FIBRES in the ventricle WALLS carry the wave of depolarization UPWARDS through the ventricle MUSCLE
- impulse causes cardiac muscle in each ventricle to CONTRACT simultaneously from APEX UPWARDS
= this forces blood UP and OUT of the heart
What does ECG stands for?
ElectroCardioGram
How can the cardiac cycle be recorded to show an ECG?
- the ELECTRICAL ACTIVITY that spreads through the heart during the CARDIAC CYCLE can be detected using ELECTRODES placed on the SKIN
- the ELECTRICAL SIGNALS can then be shown on a CATHODE RAY OSCILLOSCOPE or a CHART recorder.
- the RECORD PRODUCED by this procedure is called an ELECTROCARDIOGRAM (ECG)
Explain the P wave
the FIRST part of the trace showing the DEPOLARISATION of the ATRIA during ATRIAL SYSTOLE/contraction
Explain the QRS wave
shows the SPREAD of depolarization through the VENTRICLES resulting in VENTRICLE SYSTOLE/contraction
Explain the T wave
shows the RELAXATION and REPOLARISATION of the VENTRICLES during VENTRICULAR DIASTOLE
What does the PR interval indicate?
TIME taken for the electrical impulses to spread from the ATRIA to the VENTRICLES through the AV node
Summarize the meaning of P, QRS and T waves
P - atrial depolarization
QRS - ventricular depolarization
T - ventricular repolarization
*wave of depolarization
Heart rate calculation - beats per minute
time taken between equivalent points e.g R to R
