Animal transport 2.3 Flashcards
What are the characteristics of an open circulatory system?
-Low pressure
-No separation between blood and interstitial fluid (haemolymph)
-Dorsal tube shaped heart
-No respiratory pigment
-No respiratory gases
How does the circulatory system of an insect work?
-Materials are exchanged between haemolymph and cells in haemocoel
-Heart pumps at low pressure, fluid returns slowly from haemocoel
-Fluid doesn’t travel through vessels, but bathes tissues directly
How do closed circulatory systems work?
-High pressure
-Blood confined to vessels and is separate from interstitial fluid
-One or more pumps
-Large vessels divide into smaller vessels
-Material diffuses between vessels and interstitial fluid
-Respiratory pigment carries gases
How does the circulatory system of an earthworm work?
-Vessels joined end to end in closed loop
-Dorsal vessel (main heart)
-Blood moves backwards to tail (ventral)
-Blood moves to head (dorsal)
-5 pseudohearts
-Capillary network in intestine
-Oxygen diffuses via moist body surface
What animals use an open circulatory system?
-Insects
-Crustaceans
-Most molluscs
What animals use a closed circulatory system?
-Vertebrates
-Cephalopods
-Annelid worms
What are afferent arteries?
They bring blood to an organ
What are efferent arteries?
They bring blood away from an organ
What are the characteristics of a single circulatory system?
-Lower pressure
-Less energy to power heart
-Higher pressure to gills
-Lower pressure to body
What are the characteristics of a double circulatory system?
-High pressure
-More energy to power heart
-Lower pressure to alveoli
-Higher pressure to body cells (more risk of damage)
What circulatory system do insects have?
Open single circulation
What circulatory system do fish have?
-Closed single circulation
What circulatory system do mammals have?
-Closed double
What happens when pressuring in atria>ventricle?
Left atrium contracts, pushing bicuspid open, pushing blood to left ventricle
What happens when pressure in aorta>ventricle?
Blood caught in ‘cup’ of semilunar valves, closing them, preventing backflow
What happens when pressure in ventricle>atria?
Left ventricle contracts, blood caught in ‘cup’ of bicuspid, bicuspid shuts, preventing backflow
What happens when pressure in ventricle>aorta?
Left Ventricle contracts, semilunar valves opens
What is the cardiac cycle?
A sequence of events that make up one heartbeat
What are the 3 phases of the cardiac cycle?
-Ventricular diastole
-Atrial systole
-Ventricular systole
What is systole?
Muscle contraction
What is diastole?
Muscle relaxation
What are the characteristics of ventricular diastole?
-Muscles relax
-Volume increases
-Pressure decreases
-Semilunar valves close
-Atrioventricular valves open
What are the characteristics of atrial systole?
-Muscles contract
-Volume decreases
-Pressure increases
-Semilunar valves close
-Atrioventricular valves open
What are the characteristics of ventricular systole?
-Muscles contract
-Volume decrease
-Pressure increase
-Semilunar valves open
-Atrioventricular valves close
What does myogenic mean?
The heart can pump without stimulation from the nervous system
What is stroke volume?
The volume of blood expelled by the heart in one cycle
What is cardiac output?
Volume of blood expelled in a minute
What is the equation for cardiac output?
Stroke volume X BPM
What is the importance of the time delay at the AVN?
Allows time for atria to contract
What is the role of the Sinoatrial Node?
It’s a pacemaker and initiates the electrical signal through the atria to Atrioventricular Node
What is the role of the Atrioventricular Node?
Causes a delay and passes impulse to ventricle through Bundle of His
What is the role of the Bundle of His?
Transmits signal to Purkinje fibres
What is the role of the Purkinje fibres?
Carries impulse through walls from apex upwards
What does an Electrocardiogram do?
Measures the electrical activity of the heart
Explain the P wave
SAN generates signal causing depolarisation of atria, leading to atrial systole
Explain the QRS peak
AVN transmitted signal via Bundle of His to Purkinje fibres. Depolarisation and ventricular systole
Explain the T peak
Repolariation of ventricle causing ventricular diastole
What can an ECG show?
-Rhythm changes
-Changes as a result of a heart attack (wide QRS)
-Effects of exercise
What are the key features of an artery?
-Thicker muscular walls
-Narrow lumen (maintain pressure)
-Smooth folded endothelium (reduce friction with blood)
Describe the Tunica externa in arteries
Collagen fibres to prevent overstretching
Describe the Tunica media in arteries
-Thick layer of smooth muscle to control diameter
-Elastic fibres for strength and recoil
Describe the Tunica interna in arteries
-Single layer of smooth squamous epithelium
-Folded to allow stretch
What are the key features of veins?
-Thinner muscular walls
-Wider lumen
-Valves
Describe the Tunica externa in veins
Low number of collagen fibres
Describe the Tunica media in veins
-Thinner layer
-Some smooth muscle and elastic fibres
Describe tunica interna in veins
-Single layer of smooth squamous epithelium
Describe capillaries
Fenestrations, pores between cells allow water and solutes to pass out under pressure
What are the features of capillaries?
-Narrow
-Very thin walls
-Capillary beds, dense network with large cross section area, reduces pressure
What is filtered out of the capillaries?
-Water
-Glucose
-Amino acids
-Small proteins
-hormones
What are reabsorbed into the capillaries?
-Water
-Urea
-CO2
-Spent hormones
What do plasma proteins do to the capillaries?
Lower water potential
Where does excess fluid go?
The lymphatic system, otherwise edema occurs
What does Hb affinity mean?
How easily Hb associates/disassociates with O2
What does PPO2/CO2 mean?
Pressure exerted if it were the only gas present
What shape is the Oxygen dissociation curve?
Sigmoid, “s”
What is the importance for foetal haemoglobin to develop to adult haemoglobin?
High affinity would mean it wouldn’t release O2 readily enough for respiring tissues
