TRANSPORT IN ANIMALS Flashcards
What are features of an effective transport system?
- need fluid to carry oxygen, glucose, etc around body
- pump- creates pressure to push fluid around body (heart)
- exchange surfaces (allow O2 to leave blood- lungs, villi)
What does an efficient system include?
Tubes/vessels to carry blood
Two circuits- one to pick up O2 and other to take to tissues
What is a closed system?
Blood stays entirely in vessels
Tissue fluid bathes the cells
What is an open circulatory system?
Blood not always contained in vessels but circulates the body cavity which is called haemocoel (blood space)
Cells bathed directly in blood
How do insects pump blood around their body?
Squeeze blood towards head, flows into haemocoel
Body movements help blood flow
How is oxygen transported to cells in insects?
Blood doesn’t transport oxygen
Tubes with trachea openings called spiracles
Trachea penetrates into body= diffusion sufficient to stays insects O2 demand
What is a single circulatory system?
Blood only flows through the heart once for each complete circuit of the body
What is a double circular;atpry system?
Blood flows through the heart twice for each circuit of the body
What is the circuit called when blood pumps from the heart to lungs then back to the heart?
Pulmonary circuit
What is the circuit called when blood is pumped from the heart around the body and then back to the heart?
Systemic circuit
How does blood flow in a fish?
Heart
Gills
Body
Heart
How does blood flow in a mammal?
Heart Lungs Heart Body Heart
What is the circulation in a fish?
Closed
Single
What is the circulation in a mammal?
Closed
Double
Whats an advantage of having a double circulatory system?
Higher pressure, supplies O2 and glucose more quickly to body tissues
What is the order of blood vessels?
Arteries, arterioles, capillaries, venules, veins
What do veins contain to allow them to vasoconstrict and vasodilate?
Smooth muscle
In what vessels does blood leave the heart?
Arteries
What blood vessels carry blood back to the heart?
Veins
What is the structure of arteries?
Thick walls to withstand pressure- thick smooth muscle and elastic fibres (constrict and dilate vessels)
Folded endothelium- allows them to change size
Layer of elastic tissue- stretch and recoil
Narrow lumen
What is the structure of capillaries?
Allow exchange of materials- wall of endothelium (flattened)= one cell thick
Lumen big enough for RBC to move along
Walls are leaky= allows plasma and dissolved substances to leave blood
What is the structure of veins?
Unfolded endothelium cells (doesn’t need to change size)
Large lumen to decrease resistance
Thin layer of smooth muscle and elastic fibres
Describe valves
- return the blood at low pressure, veins are squeezed by surrounding muscles
- prevent backflip
- flaps or unfolding of endothelium
What do coronary arteries supple to heart muscles?
O2 and nutrients (e.g. glucose) for aerobic respiration
What do cardiac veins remove?
Waste carbon dioxide
What does restricted flow in vessels cause?
Angina and blockages of arteries
Leads to myocardial infarction (heart attack), as heart muscles are deprived of oxygen
What separates the two sides of the heart?
Septum
Prevents oxygenated and deoxygenated blood mixing
What valves separates the atria and ventricles?
Atrio-ventricular valves
- tricuspid (right)
- bicuspid (left)
What is the role of tendinous chords?
Prevents valves turning inside out
Where does the aorta transport blood to and from?
Left ventricle to head and body
Where does the pulmonary artery transport blood to and from?
From left atrium To lungs (only artery with deoxygenated blood)
Where does the vena cava transport blood to and from?
From body and head
To right atrium
Where does the pulmonary vein transport blood from?
From the lungs
To left atrium (only vein with oxygenated blood)
What forms the heart muscles?
Intercalated discs
Nucleus (one per cell)
Branched muscle fibres- produces squeezing muscle force by spreading contraction
Spaces between cells filled with loose connective tissue
What does it mean by the cardiac muscles being myogenic?
Can generate it’s own impulse
Contracts and relaxes without any nerve stimulation
In cardiac muscles, why are cells branched?
Produce cross bridges
Help spread contractions and allows heart to produce squeezing force
What is the function of intercalated discs in the cardiac muscles?
Facilitate a synchronised contraction
Describe atrial systole
Atria contracts
Small pressure in atria (less muscles)
Blood forced into ventricles through atria-ventricular valves
Ventricles fill with blood
No back glow because semi-lunar valves close
Describe ventricular systole
Ventricle contracts
Increases pressure
Higher pressure in ventricles than atria, pushing atria-ventricualr valves shut
High pressure in ventricles opens semi-lunar valves in aorta and pulmonary artery
Describe diastole
Atria and ventricles relax
Elastic tissue recoil to help ventricles go back to original size
Decreased pressure in ventricles
High pressure pulmonary artery and aorta= semi-lunar valves to shut
Blood flows into atria
Ventricles relax= atria fill up with blood= higher pressure in atria
Opens atria-ventriucalr valves
Blood flows into ventricles
What does the ‘lub dub’ sound of the heart mean?
Lub= atrioventricular valves shutting Dub= semilunar valves shutting
What are cardiac muscles
Myogenic- relax and contract on their own
Where is the Sino atrial node
Right atrium
What does the SAN initiate
Electrical wave of excitation (depolarisation), passes over walls of atria causing them to contract
What stops electrical waves passing into ventricles
Band of non-conducting collagen fibres between atria and ventricles
Why must the wave of exception not be passed into the ventricles
Blood from atria needs to be pushed out before entering ventricles
What is the atrioventricular node
Small group of non-conductive collagen fibres at top of septum
Function of AVN
Depolarisation through a small wave, travels down purine tissues and into septum
Function of purine tissue
Conducts electrical wave upwards and outwards through ventricle wall
Causing muscle contract bottom up
What are the stages of an ECG trace
Starts in right atrium, SAN (myogenic)- pacemaker
Muscles in SAN contract- electrical impulse through muscles into atria- atria contracts P WAVE
Impulse enters AVN, impulse down ventricles
Impulse move down septum along purkyne tissue, into ventricles up walls- QRS
Ventricles relax T WAVE, SAN contracts again and sequence repeats
Explain bradycardia
Heart rate slows below 60bpm
May need pacemaker
Explain tachycardia
Heart rate very rapid, over 100bpm
May need medication or surgery
Explain ectopic heartbeat
Extra heart beats out of normal rhythm
Can happen once a day, could be fatal
Explain atrial fibrillation
Abnormal heart rhythm
Rapid electrical impulses generated in atria
Contract very fast, up to 400 times a minute, down always contract properly so only some impulses are passed onto ventricles
Heart doesn’t pump effectively
Explain ventricular fibrillation
Rapid and irregular electrical activity
Ventricles unable to contract in a synchronised manner
Loss of cardiac output
What is blood made up of
55% plasma (water, CO2, mineral ions)
1% platelets (WBC)
44% RBC
What is tissue fluid
Fluid that bathes cells in tissues
Formed from plasma that has leaked out of capillaries
Essential for exchange of materials
How is tissue fluid formed
At end of arteriole blood has high hydrostatic pressure
Pushes fluid through gaps in capillaries
Tissue fluid has small hydrostatic pressure
Oncotic pressure affects movements of fluid
At the arteriole end of capillaries there is a NET hydrostatic pressure forcing fluid out capillary
What is oncotic pressure
Used rather than water potential in blood as its not a solution
Capillary wall permeable to ions so osmosis will not occur in normal way
How is tissue fluid returned to the blood
At venue end of capillary the hydrostatic (blood) pressure is much lower due to loss of fluid
However, plasma proteins are too large to fit through gaps in capillaries so there is still oncotic pressure
Venule end of capillary has NET movement of fluid into capillary due to oncotic pressure
What do lymph vessels collect and return to the blood system
10% of fluid which has leaked from capillaries
Explain lymph vessels
Allow tissue fluid to flow in buy not out (valves)
Valves allow proteins through as proteins too large to enter capillaries
What are adaptions to erythrocytes
Very small (7-8 micrometer)- squeeze through capillaries, short diffusion pathway
Biconcave disc- larger SA:V
No nucleus, mitochondria etc- more space for haemoglobin
Describe haemoglobin
Globular
4 polypeptide chains
Each polypeptide has a team prosthetic group contain iron
Haem group has affinity for oxygen, iron attracts and holds onto oxygen = oxyhemoglobin, reversible- unloads non body tissues
How is oxygen taken up
O2 molecules diffuse into blood plasma from alveoli
O2 binds to haemoglobin forming oxyhemoglobin
Taking O2 out of solution maintains a steep conc gradient
Meaning more O2 enters blood and diffuses into RBC
How is oxygen released
O2 molecules needed in the tissue for aerobic respiration
Oxyhemoglobin unloads releasing O2
What does haemoglobin’s affinity for oxygen depend on
Partial pressure of oxygen
As partial pressure increases so does affinity
O2 loads onto Hb to form oxyhemoglobin where there’s a high po2, unloads when low po2
Why is the disassociation curve S shaped?
- first O2 molecule binds slowly with first harm group
- binding of first harm group causes haemoglobin shape to change - as a result it is easier for 2nd and 3rd O2 mole to bind to harm group- curve becomes steeper
- curve flattens because its then harder for fourth harm group to combine to harm group
How is carbon dioxide transported
5% in dissolved plasma
10% in haemoglobin= carbaminoheamoglobin
85% diffuse into erythrocytes where enzyme carbonic anhydrase catalyses it E
Explain the chloride shift
Hydrogen carbonate ions diffuse out erythrocyte into plasma
Causes chloride ions to enter erythrocytes to balance change
Explain the Bohr effect
H+ ions cause an increase in cell acidity
Haemoglobin acts as buffer, take up H+ to form haemoglobonic acid
Oxyhaemoglobin releases oxygen
