Animal Transport Flashcards
Transport def
the movement of substances such as oxygen, nutrients, hormones, waste and heat around the body
3 factors that influence need for transport system
- size
- SA:Vol ratio
- level of metabolic activity
Need for a transport system (5 reasons)
- Metabolic demands of most multicellular animals are high, so diffusion over long distances is not enough to supply the organism
- SA:Vol gets smaller as animal gets bigger
- Molecules such as enzymes or hormones may be made in one place but needed in another
- Food will be digested in one organ system but needs to be transported to every cell for use in respiration
- Waste products need to be transported to our excretory organs e.g. kidney, liver, lungs, skin
Effective transport system
- Fluid/transport medium to carry nutrients e.g. blood
- Pump e.g. heart
- Exchange surfaces e.g. capillaries, arteries, veins
Efficient transport system
- Other blood vessels e.g. arterioles, venules
- Double circulatory system
Single circulatory system
blood flows through the heart once for each circuit of the body
E.g. fish
+ less complex, doesn’t require complex organs
– low blood pressure
– slow movement of blood
– activity level of animal tends to be low
Double circulatory system
blood flows through the heart twice for each circuit of the body
E.g. birds, most mammals
+ fast flow of blood
+ high pressure
+ heart can pump blood further around the body
Open circulatory system
Blood is not held in vessels
E.g. insects
– blood pressure is low, blood flow is slow
– circulation of blood may be affected by body movements or lack of body movements
Closed circulatory system
Blood is held in vessels
E.g. all vertebrates (i.e. fish & mammals)
+ higher pressure so that blood flows more quickly
+ More rapid delivery of oxygen and nutrients
+ More rapid removal of carbon dioxide and other waste
+ Transport is independent of body movements
How is the left ventricle adapted to suit its function
- thicker
- more muscle
- pumping blood to whole body
- at higher pressure
Pathway of blood through the heart
- Deoxygenated blood flows through the vena cava into the right atrium
- Through the tricuspid valve into the right ventricle
- Through the semilunar valve out of the pulmonary artery where blood is taken to the lungs
- Oxygenated blood flows through pulmonary vein into the left atrium
- Through the bicuspid valve into left ventricle
- Through the semilunar valve out of the aorta to the rest of the body
Arteries
Take blood away from the heart
- endothelial layer- one cell thick and lines blood vessels
- lots of smooth muscle- strengthens arteries to withstand high blood pressure, and contract and relax to control blood flow
- lots of elastic tissue- stretches and recoils to maintain BP
- narrower lumen- helps maintain high BP
pulse is present
Arterioles
Controls blood flow throughout the body
- similar structure to arteries but smaller
- thick muscular layer to contract and relax to control blood flow
- smaller amount of elastic fibre
- large number of muscle cells allows them to contract and regulate blood flow
Venules
Connect capillaries to veins
- little bit of elastic fibre
- no smooth muscle as blood travels at low pressure
- larger lumen- reduces friction between blood and endothelial layer of vein
- valves are present
Capillaries
Allows gas exchange to take place
- one cell thick- reduces diffusion disatnce
- very small lumen- forces blood to travel slowly so gas exchange can occur
- large number of capillaries- covers large surface area for more gas exchange
- form capillary beds which are important exchange surfaces within the circulatory system
Diastole
Relax
Systole
Contract
Process of Diastole
- all chambers relax
- elastic recoil - increase volume, so more space for blood
- blood flows in
AV valves open
semilunar valves closed
Atrial systole
- atria contract- increase pressure, decrease volume
- ventricles relax
- push blood from atria into ventricles
AV valves open
semilunar valves closed
Ventricular systole
- ventricles contract- increase pressure, decrease volume
- atria relax
- apex produces larger contractions - force blood upwards
AV valves closed
semilunar valves open
Cardiac output
Volume of blood pumped out by the heart per minute
- cm3min-1
Heart rate
Number of beats per minute
• BPM
Stroke volume
Volume of blood pumped out of the left ventricle per beat
Fibrillation
Contractions aren’t synchronised
Conduction of cardiac cycle
- SAN initiates wave of electrical excitiation which spreads over atrial wall, causing atria to contract (atrial systole)
- A band of fibres between the atria and ventricles stops the wave of excitation passing directly to the ventricular walls
- The wave of excitation reaches the AVN on the septum
- Wave of excitation spreads down to the bundle of His and then the Purkyne fibres
- Ventricles contract simultaneously
- Ventricles contract from apex upwards to pump blood upwards into arteries to completely empty the ventricles
ECG’s aim
To monitor electrical activity of the heart
P, QRS, T
P wave- caused by the depolarisation of the atria, which results in atrial systole
QRS complex- caused by depolarisation of the ventricles, which results in ventricular contraction (systole)
- this is the largest wave because the ventricles have the largest muscle mass
T wave- caused by the repolarisation of the ventricles, which results in ventricular diastole
Tachycardia
• heart rate is faster than normal
• More than 100 bpm at rest
• Can start in upper or lower chamber of your heart
• Range from mild to life threatening
Bradycardia
• heart rate is slower than normal
• Resting heart rate of less than 60 bpm
• Fit people/athletes tend to have lower heart rate (resting)
Atrial fibrillation
• abnormal heart rhythm or arrhythmia
• Causes heart to beat abnormally
• Top chambers (atria) twitch- known as fibrillation
Ectopic heartbeat
Type of irregular heart beat
• Heart contracts too soon
• Heart can skip a beat or feel like it’s racing or fluttering
Hydrostatic pressure
Pressure that a fluid exerts when pushing against the sides of a vessel or container
- pushing force
Oncotic pressure
Pressure created by the osmotic effects of the solutes
- pulling force
Hypertonic
High in solutes therefore low WP
Hypotonic
Low in solutes therefore high WP
Formation of tissue fluid
Artery —> arteriole —> capillary —> venule —> vein
- due to the contraction of the heart, blood is at high hydrostatic pressure at the arteriole
- between cells of the capillary walls, there are small gaps
- the hydrostatic pressure is greater than the osmotic pressure
- this forces fluid out of the capillaries carrying plasma and dissolved substances e.g. oxygen, glucose
- RBC’s, WBC’s, proteins can’t leave capillary because they are too large
Which end of the capillary is hydrostatic pressure lower
- hydrostatic pressure is lower at the venule end
Hydrostatic & oncotic pressure in: blood plasma, tissue fluid and lymph
hydrostatic pressure
Blood plasma: high
Tissue fluid: low
Lymph: low
oncotic pressure
Blood plasma: high
Tissue fluid: low
Lymph: low
Partial pressure
The amount of pressure exerted by a gas, relative to the total pressure exerted by all bases in the mixture
- kPa
Oxyhaemoglobin dissociation curve
- At low pO2 - low saturation of haemoglobin with oxygen haem group is at centre- makes it difficult to associate
- As pO2 increases faster increase in saturation
• higher conc if O2 = steeper gradient for diffusion of O2 into haemoglobin
• When one O2 associated- conformational change in shape of haemoglobin makes it easier for O2 to diffuse in and associate
• Known as positive cooperativity - At high pO2- saturation is high but levels off as unlikely to reach 100%
• when 3 O2 associated, difficult for the fourth molecules to diffuse in and associate to reach 100% even at highest pO2
Bohr shift
- in lungs there is less CO2
- less CO2, higher pH, shape increases affinity for oxygen and makes it easier to load
Increase in carbon dioxide moves the curve to the right
myoglobin curve goes straight up then curves round at the top
Fetal haemoglobin
Higher affinity for oxygen than adult haemoglobin
• foetus gets oxygen from placenta
• pO2 in placenta is low
• Maternal haemoglobin releases oxygen
• Fetal haemoglobin has a higher affinity for oxygen
• This maintains a diffusion gradient towards the foetus
Diagram: s shapes curve, foetal curve is slightly to the left/above
Chloride shift
- CO2 from respiring tissues diffuses into RBC
- It reacts with water to from carbonic acid, catalysed by enzyme carbonic anhydrase
- Carbonic acid dissociates to give hydrogen ions (H+) and hydrogencarbonate ions (HCO-3)
- This increase in H+ ions causes oxyhaemoglobin to unload its oxygen so that haemoglobin can take up the H+ ions
- This forms haemoglobinic acid and stops H+ ions increasing cells acidity
- HCO-3ions diffuse out of the RBC and transported to blood plasma
- To compensate for loss of HCO-3ions from the RBC, chloride ions (Cl-) diffuse into the RBC
Chloride shift simplified
CO2 in
CO2 + H2O ————> carbonic acid
Catalysed by enzyme carbonic anhydrase
Carbonic acid ———> H+ + HCO-3
HbO2 unloads O2, takes up H+
Hb + H+ ———> haemoglobinic acid
HCO-3 in, Cl- in
