Mod 3 Chap 8: Transport In Animals Flashcards
Explain the need for specialized transport systems in animals.🌟
- bigger organisms = greater distance between cells + outside of the body, so diffusion too slow for these bigger organisms to transport substances in and out
- also, metabolic demands of multicellular animals = high so diffusion over long distances = not enough to supply quantities needed
- SA:V ratio smaller in bigger multicellular organisms, so diffusion distances = bigger + amount of SA to absorb / remove substances becomes smaller too
- waste products of metabolism need to be removed from cells + transported to excretory organs
- food digested in one organ system, but needs to be transported to every cell for respiration
- hormones or enzymes may be made in one place but needed in another
So all require specialized transport systems.
What are the different types of circulatory systems.🌟
- open circulatory systems
- closed (single / double) circulatory systems
Describe open circulatory systems.🌟
- mostly found in insects
- blood or ‘haemolymph’ not enclosed in blood vessels at all times
- haemolymph pumped straight from heart into open body cavity of animal called ‘haemocoel’, via main artery
- transport medium in haemocoel is under low pressure + comes into direct contact w/ tissues + cells
- exchange between transport medium + cells takes place here
- transport medium then returns to heart through open ended vessel
- however, oxygen transported differently, via tracheal system
Describe single closed circulatory systems.🌟
e. g fish
- blood flows through heart, pumped out + travels all round body before returning back to heart, so travels once through heart for each complete circulation of body
- blood passes through 2 sets of capillaries (exchanging O2 + CO2 in one, + exchanging substances between cells in other) before returning to heart
- blood pressure now V low as capillaries / vessels are v narrow, so blood returns to heart slowly
- this limits efficiency of exchange processes, meaning activity levels in animal w/ single closed circulatory systems = relatively low
Describe double closed circulatory systems.🌟
e. g. Humans
- most efficient system for transporting substances around body as has 2 separate circuits
- one takes blood to lungs to pick up O2 (pulmonary circulation) + unload CO2
- other carries blood w/ O2 + nutrients around body to tissues + cells, then picks up waste (systemic circulation)
- so blood travels twice through heart for each circulation of body
- this increases pressure of blood after passing through lungs, so blood flows more quickly to body tissues when needed urgently.
Describe the structure and function of the arteries.🌟
Function:
- carry blood away from heart to tissues in body
- carry oxygenated blood, (apart from pulmonary artery = deoxygenated to lungs)
- carry blood at high pressure
Structure:
- small lumen but thick walls
- elastic fibres: allow arteries to withstand force of blood pumped out of heart + helps stretching to take larger vols of blood
- smooth endothelium lining: blood flows easily over it
- thick wall: w/ collagen for strength to contain high pressure blood
- some smooth muscle
Describe the structure and function of the arterioles.🌟
Function:
- link arteries to capillaries
- constrict or dilate to control flow of blood into organs (vasodilation and vasoconstriction)
Structure:
- more smooth muscle + less elastin than arteries
- little pulse surge
- some collagen
Describe the structure and function of the veins.🌟
Function:
- carry blood towards heart from cells in body
- mostly carry deoxygenated blood, but pulmonary vein carries oxygenated blood from lungs to heart
- carry low pressure blood
- veins flattened by surrounding muscle to force blood up vein (hence why movement is needed to prevent blood clot)
Structure:
- large lumen but thin walls, so carry large vol of blood
- valves: prevent back flow of blood
- more collagen than elastic fibres
- smooth, thin endothelium lining so blood flows easily
Describe the structure and function of the venules.🌟
Function:
- carry deoxygenated blood from capillaries to larger veins, so link capillaries w/ veins
- several venules join to form a vein
Structure:
- v thin walls
- small amount of smooth muscle
Describe the structure and function of the capillaries.🌟
Function:
- link arterioles w/ venules
- substances exchanged through capillary walls between tissues + blood
- mostly receives oxygenated blood from arterioles
- by time blood leaves capillary for venules, it is deoxygenated.
Structure:
- microscopic blood vessels
- lumen so small that red blood cells travel through single file
- large gaps between endothelial cells in capillary walls: substances can pass out of capillaries into fluid of surrounding cells
- large SA for diffusion of substances into + out of blood
- cross-sectional area of capillaries = greater than arterioles supplying them blood, so rate of blood flow falls, giving more time for exchange of materials
- walls only one endothelial cell thick, giving v thin layer for diffusion.
Describe the formation of tissue fluid from blood plasma.🌟
- blood under high pressure, as flows through arterioles into capillary at arteriole end of capillary, from surge of blood occurring w/ heart contractions (this = hydrostatic pressure, so here = high)
- oncotic pressure, attracting water in by osmosis, = lower than HP, so fluid squeezed out of capillaries
- fluid fills spaces between cells, = called tissue fluid
- tissue fluid has same composition as blood plasma, just without red blood cells + plasma proteins
- diffusion between blood + cells occurs through tissue fluid.
Describe what the cardiac cycle involves.🌟
- includes all events taking place in heart during one heart beat
- when cardiac muscle contracts, pressure in heart increases, so blood forced out (systole)
- when cardiac muscle relaxes, pressure in heart decreases, so blood flows in (diastole)
- ‘lub’ sound of heartbeat caused by closing of valves between atrium + ventricle due to increased pressure
- ‘dub’ sound of heartbeat comes from closing of semi-lunar valves due to increased pressure in arteries
Explain the order of events during one heartbeat (the cardiac cycle).
- atrial pressure in left atrium = low, but starts to rise, + is highest when walls contract forcing blood into left ventricle. Left ventricular pressure increases when filled w/ blood.
- atrioventricular valve (bicuspid) valve closes + walls relax
- left ventricle thick wall contracts, causing dramatic rise in ventricular pressure, w/ help from closed AV valve (bicuspid)
- semi lunar valves open, blood passes into aorta so pressure in aorta rises
- ventricle pressure decreases as walls relax, blood empties from ventricles. Aortic pressure (in aorta) falls due to elasticity of aorta wall creating recoil action
- semi lunar valves closes. Recoil in aorta causes temporary rise in aortic pressure at start of relaxation phase of ventricle (where ventricular pressure is still falling)
- pressure falls to lowest in ventricles, walls completely relax. Atrioventricular / mitral valves open, some blood moves into ventricle so pressure slightly decreases in atrium
- aortic pressure continues to decrease due to relaxation caused by recoil of walls due to elasticity
- ventricular volume rises as atria both contract, ventricles fill with blood
- ventricular volume drops suddenly as blood forced out into aorta when semi lunar valves open
- volume in ventricles increases again, ventricles fill with blood
Describe the use of ECG traces.
- Electrocardiograms record electrical activity in heart by measuring electrical differences in skin, as a result of heart’s electrical activity.
- electrodes stuck to clean skin to give good contact for reliable results
- signal from each electrode fed into machine which produces an ECG
- used to help diagnose heart problems
Explain the interpretation of ECG's by defining the terms a) Bradycardia b) Tachycardia c) Ectopic heartbeat d) Atrial Fibrillaation 🌟
a) Bradycardia: when heart rate slows to below 60bpm. Can occur in fit people as training slows heartbeat, but severe bradycardia may need artificial pacemaker to keep best steady
b) Tachycardia: when heart rate = v rapid, over 100 bpm. Often normal, e.g, when exercising. If abnormal, may be caused by problems w/ electrical control of heart, may need surgery / medication.
c) Ectopic heartbeat: extra heartbeats outside of normal rhythm. Most people have at least one a day, usually normal but can be linked to serious conditions when v frequent.
d) Atrial fibrillation: example of an Arrhythmia (abnormal rhythm of heart). Rapid electrical impulses generated in atria, + atria contract v fast (fibrillate). if don’t contract properly + only some impulses are passed onto ventricles which contract much less often, heart will not pump blood v effectively.
