Module 4: Circulation and Gas Exchange Flashcards
Outline 4 components of diffusion and the circulatory system
- cells exchange oxygen and nutrients for carbon dioxide and waste
- diffusion is proportional to the square of distance
- a circulatory system is more efficient
- open vs. closed system
List 3 components of Open circulatory system
- heart pumps haemolymph
- simple and easy to maintain
- less energy and lower pressures
List 3 components of Closed circulatory system
- blood and small branch vessels into interstitial fluid
- increased efficiency at higher pressures
- meets high metabolic demand
Describe Single Circulation
- simpler organisms exhibit single circulation
- as they are constantly moving (swimming), the heart does not need to pump blood as powerfully
- blood is pumped by the heart, to the gills to be oxygenated, then to the rest of the body and back to the heart
Outline Double Circulation
- more complex organisms exhibit a more complex circulatory system
- the pulmonary (lung) and systemic (body) circulatory systems are separated, but blood mixes in the heart
Describe segmented double circulatory systems in mammals
- there is separation of the pulmonary circuit and systemic circuit
- there is separation of chambers of the heart, so oxygenated blood and deoxygenated blood does not mix
Draw a diagram of the heart
- see booklet for full diagram
List the 3 steps of the Cardiac Cycle
- Atrial and ventricular diastole (atrioventricular valves open, semilunar closed) = 0.4 seconds
- Atrial systole, ventricular diastole = 0.1 seconds
- Ventricular systole, atrial diastole = 0.3 seconds
Define systole and diastole
Systole = contraction Diastole = relaxation
Define and give the formula for Cardiac Output
Cardiac output= amount of blood leaving the left ventricle per minute
Cardiac output = heart rate * stroke volume
= bpm* L
= L*min
What is the cardiac output for the human heart at rest
5 L / min
What is the heart rate at rest
70 beats/minute
List/describe briefly the 3 muscle types
Skeletal: voluntary, striated
Smooth: non-striated
Cardiac: involuntary, striated
Describe some components to do with cardiac muscle cells and their self-excitability
- contraction occurs through excitation of pacemaker cell
- spontaneous action potential
- depolarisation wave
Describe how the Sinoatrial node/pacemaker sets rate and timing
- signal travels to atrioventricular node via a wave of depolarisation across cells
- impulses are delayed at AV node
- signal sent to Purkinje fibres, makes ventricles contract
What is the rate and timing of ventricle contraction affected by
- parasympathetic and sympathetic nervous systems
- hormones e.g. adrenaline
- body temperature
Describe the structure/function of Arteries
- thick
- muscular (smooth muscle)
- high pressure
Describe the structure/ function of Veins
- thin
- weak muscle
- valves to prevent back flow
- low pressure
Describe the structure/function of Capillaries
- 1 cell thick wall
- endothelial cells: lipid-soluble substances pass through, plasma proteins cannot cross, exchangeable proteins moved across by vesicular transport
- water-filled pores: small, water-soluble substances pass through
- precapillary sphincters control flow of blood
- capillary smooth muscle constricts the arteriole
- the lymph system drains interstitial fluid and keeps blood pressure up
Draw a flow diagram from the SA to contraction (5 steps)
- see booklet for full diagram
Draw a diagram of pressure between the different ends of the capillary and also outline osmotic pressure
- see booklet for full diagram
List/describe the 3 components of plasma
- Albumin: osmotic balance and pH buffering
- Fibrinogen: clotting
- Immunoglobulins: defence (antibodies)
What are the 3 main components of blood
- Plasma
- Buffy coat: platelets and white blood cells
- Red blood cells: erythrocytes
What does an erythrocyte increase indicate:
- erythrocyte increase: blood doping in sport: increases number of red blood cells carrying oxygen
Outline the 7 steps in blood clotting
- cuts in the skin are sealed by blood clotting; clotting factors are released from platelets, the cascade results in the rapid conversion of fibrinogen to fibrin by thrombin
1. Endothelial damage is sensed
2. Platelets are cell fragments in the blood
3. Clotting factors are released from damaged tissue or platelets
4. This sets off a cascade of reactions where the product of a reaction catalyses the next: the ensures that clotting only happens when necessary, it is a very fast process
5. In the final reaction, fibrinogen is altered by thrombin to form long proteins called fibrin
6. Fibrin is insoluble and forms a mesh of fibres across wounds
7. This forms a semi-solid clot; if exposed to air, the clot dries to form a scab
List 5 causes/consequences of blood clot formation in coronary arteries
- deposits of plaque can be caused by high blood pressure (hypertension), high blood cholesterol, smoking, obesity, or a lack of exercise
- if deposits of plaque in coronary arteries rupture, blood clots form (coronary thrombosis) which may completely block the artery
- this means that an area of cardiac muscle receives no oxygen and stops beating
- this is called a heart attack. Uncoordinated contraction of cardiac muscle is fibrillation
- sometimes the heart recovers, but severe heart attacks can be fatal
Briefly outline how gas exchange occurs across specialised respiratory systems
- passive diffusion across a moist surface in order to exchange oxygen and carbon dioxide, to allow for conversion of fuel to ATP
Briefly outline partial pressures and diffusion of gas
- partial pressure (pp) refers to the pressure exerted by a particular gas in a mixture of gases
- the total pressure of a group of gases is equal to the sum of the pressure of the gases along in the same volume
- partial pressure applies to liquids (Henry’s law)
- solubility of a gas in liquid is proportional to pp of that has in equilibrium with the liquid
- gases diffuse from regions of high pp to low pp (Fick’s law of diffusion)
Discuss quantitative partial pressures
- pp is measured in mmHg (mm mercury)
- 760mmHg = 101 kPa = atmospheric pressure
- air contains: 21% oxygen
pressure of oxygen= 0.21 * 760 = 160 mmHg
pressure of oxygen= 0.21 * 101 = 21.2 kPa
Outline mechanisms of transport of gases in blood
- respiratory pigments (low solubility of gas in blood)
- haemocyanin (blue/green)
- haemoglobin (red/brown)
- increases from 4.5mL to 200mL oxygen/L in blood (uses 2L/min)
Discuss gas exchange methods in gills
- counter-current flow makes for efficient gas exchange in water environments
- gills are organisations of capillary networks where arteries lead to and veins lead from a web of capillaries called lamella
- water flows parallel between the lamella, perpendicular to veins and arteries
- exchanges oxygen with carbon dioxide in blood
- very efficient system, results in only slightly lower pp of oxygen in blood than in water
Discuss gas exchange methods in trachea
- trachea lead to air sacs which diffuse oxygen directly into body cells
Discuss gas exchange methods in lungs
- lungs have a high surface area due to branching, leading to efficient gas exchange
- gas exchange in alveoli- capillaries
- mammals utilise double circulation: more efficient than single or an average of the systems
Discuss how breathing ventilates the lungs
- amphibia exhibit positive pressure breathing
- mammals exhibit negative pressure breathing
Outline how breathing ventilates the lungs in: Inhalation
- diaphragm contracts: moves down
- rib cage expands: rib muscles contract
Outline how breathing ventilates the lungs in: Exhalation
- diaphragm relaxes: moves up
- rib cage contracts (rib muscles relax)
Discuss the pleural sac
- the pleural sac is a double membrane around the lung, containing pleural fluid
- at rest, elastic recoil of the chest pushes outwards, lung creates inward pull
- (negative) 3mmHg inter pleural pressure
- if the sealed pleural cavity is opened, air flows in and collapses the lung
List the 5 steps of breathing regulation
- Homeostasis (7.4 pH blood)
- Low pH caused by rising carbon dioxide (dissolves to form carbonic acid: exercise)
- Sensors in major blood vessels detect decreases in blood and send signal to medulla, medulla detects decrease in pH of cerebrospinal fluid
- Signals to rib and diaphragm muscles increase rate and depth of ventilation
- Carbon dioxide levels return to normal
List the relative pressures of oxygen and carbon dioxide throughout the breathing cycle
Inhaled: - oxygen= 160 mmHg - carbon dioxide= 0.2 mmHg Alveolar spaces: - oxygen= 104 mmHg - carbon dioxide = 40 mmHg Oxygenated blood: - oxygen= 104 mmHg - carbon dioxide= 40 mmHg Body Tissue: - oxygen= <40 mmHg - carbon dioxide= >45 mmHg --> approx. equal to oxygen Deoxygenated blood: - oxygen= 40 mmHg - carbon dioxide= 45 mmHg Exhaled: - oxygen= 120 mmHg - carbon dioxide= 27 mmHg
List 4 points with regards to positive cooperatively of haemoglobin
- haemoglobin has less affinity to oxygen at low pH (high carbon dioxide)
- therefore, more oxygen can be unloaded to tissues during exercise (haemoglobin dissociation curve)
- adaptions of blood in diving mammals
- oxygen saturation is higher in a foetus than in its mother at the same pp
Discuss oxygen storage and oxygen conservation in adaptions of blood in diving mammals
Oxygen storage: - large volume of blood - large spleen (24 litres blood) - high concentration of myoglobin in muscles (red muscle) Oxygen Conservation: - decrease heart rate - decrease blood supply
