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biology > B8 - Transport in animals > Flashcards

B8 - Transport in animals Flashcards

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1
Q

Why do animals need specialised transport systems?

A
  • high metabolic demands (require lots of oxygen/produce lots of waste products)
  • small SA:V ratio (SA available for absorption/removal decreases)
  • larger size (increase in diffusion distance, which decreases rate of diffusion/its efficiency)
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2
Q

What are the features of a circulatory system?

A
  • liquid as a transport medium that circulates around the system
  • blood vessels that carry the transport medium
  • pumping mechanism that moves the fluid around the system
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3
Q

What are the different types of circulatory systems?

A
  • single (closed):
    • blood flows through the heart and is pumped out to travel around the body, then returns to the heart
    • (blood passes through two sets of capillaries)
  • double (closed):
    • blood travels through the heart twice for each circuit of the body
    • (each circuit passes through one capillary network)
  • open:
    • very few vessels that contain the transport medium
    • it comes into direct contact with the tissues/cells
  • closed:
    • blood is enclosed in blood vessels and does not come into direct contact with cells
    • the blood is pumped around under pressure
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4
Q

What is the open circulatory system? (insects)

A
  • very few vessels to contain the transport medium
  • pumped straight from the heart to the body cavity
  • open body cavity = haemocoel
    ‎
  • transport medium is under low pressure
  • comes into direct contact with the tissues and cells
    • where exchange takes place between the transport medium and cells
      ‎
  • found in insects and other invertebrates
    • insect blood = haemolymph
    • does not carry CO2 or O2 (transports food/nitrogenous waste/cells involved in disease defence)
      ‎
  • membrane splits body cavity
  • heart extends along thorax and abdomen
  • ** steep diffusion cannot be maintained and amount of haemolymph cannot be varied **
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5
Q

What is the closed circulatory system?

A
  • blood is pumped and enclosed within blood vessels
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6
Q

What is the single closed circulatory system?

A
  • blood passes through the heart once in each complete circulation, and is transported within blood vessels
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7
Q

What is the double closed circulatory system?

A
  • blood is pumped through the heart twice for each circuit of the body
  • blood is enclosed within blood vessels
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8
Q

What are some components of blood vessels?

A
  • elastic fibres:
    • composed of elastin
    • allows vessel to stretch and recoil (flexibility)
  • smooth muscle:
    • contracts/relaxes
    • changes the size of the lumen
  • collagen:
    • provides structural support
    • maintains shape/volume of vessel
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9
Q

What are arteries?

A
  • carry blood away from the heart to the body tissues
    • carries oxygenated blood
    • except the pulmonary/umbilical artery (carry deoxygenated blood from heart to lungs)
  • blood is under higher pressure
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10
Q

What are artery walls made of?

A
  • elastic fibres (inner layer):
    • helps to withstand the force of blood pumped away from heart
    • allows them to stretch and increase blood volume
    • they recoil and return to original size (evens out surges of blood)
    • generates blood pressure with the stretching and recoiling
  • smooth muscle (middle layer)
  • collagen (outer layer):
    • provides strength to withstand the high pressure
  • endothelium - smooth layer which allows blood to easily flow over it
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11
Q

What is the structure of arteries?

A
  • small lumen to maintain high pressure as the blood is transported around the body
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12
Q

What are arterioles?

A
  • they are vessels that link the arteries and the capillaries
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13
Q

What are arterioles made of?

A
  • less elastin:
    • they have little pulse surge (do not need to eliminate)
  • more smooth muscle:
    • allows the walls to constrict/dilate to control flow of blood into certain organs
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14
Q

What is vasoconstriction?

A
  • when the smooth muscle of the arteriole wall constricts and prevents the flow of blood into a capillary bed
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15
Q

What is vasodilation?

A
  • when the smooth muscle of the arteriole wall relaxes and allows blood to flow into the capillary bed
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16
Q

What are capillaries?

A
  • they are microscopic vessels that link the arterioles with the venules
    • form an extensive network through all the tissues of the body
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17
Q

What is the structure of capillaries?

A
  • small lumen:
    • red blood cells have to travel in single file
  • large enough gaps between endothelial cells (wall):
    • where substances pass out into the fluid
    • ** except the capillaries in the central nervous system (tight junctions) **
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18
Q

How are capillaries adapted to their function?

A
  • thin wall (one cell thick):
    • allows for short diffusion distance
    • substances can be exchanged through the capillary walls between the tissue cells/blood
  • large SA:
    • helps for efficient diffusion of substances into and out of the blood
  • greater cross-sectional area:
    • rate of blood flow falls
    • the relatively slow movement allows for enough time for exchange of substances
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19
Q

What are veins?

A
  • they are blood vessels that carry blood away from the cells towards the heart
    • carry deoxygenated blood
    • except pulmonary vein (oxygenated) and umbilical vein (during pregnancy) carries ox. blood from placenta to foetus
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20
Q

What are vein walls made of?

A
  • lots of collagen
  • relatively less elastic fibre (pulse is absent)
  • they do not need to withstand a high blood pressure
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21
Q

What is the structure of veins?

A
  • larger lumen
  • valves in medium-sized veins to prevent backflow
  • thin lining (endothelium) allowing for easy blood flow
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22
Q

What are venules?

A
  • they are blood vessels that link capillaries with veins
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23
Q

What are venules made of?

A
  • very thin walls
  • little smooth muscle
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24
Q

How does the body overcome low pressure/gravity?

A
  • veins have one-way valves:
    • close when blood flows backwards
  • bigger veins run through active muscles:
    • when muscles are active they squeeze the veins, forcing blood towards the heart
    • valves prevent backflow when muscles relax
  • breathing movements act as pump:
    • pressure changes and squeezing actions move blood in chest veins towards the heart
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25
Q

What does blood consist of?

A
  • plasma: 55%
    • carries dissolved glucose, amino acids, mineral ions, hormones
    • large plasma proteins (albumin, fibrinogen, globulins)
    • also transports rbcs and wbcs
    • carries platelets (fragments of large cells found in red bone marrow)
26
Q

What are the functions of blood?

A
  • transport of:
    • O2 to/CO2 from respiring cells
    • digested food from small intestine
    • nitrogenous waste products from cells
    • chemical messages (hormones)
    • food molecules from storage compounds
    • platelets to damaged areas
    • cells/antibodies (immune response)
      ‎
  • maintains steady body temp.
  • acts as buffer, minimises pH changes
27
Q

What is tissue fluid?

A
  • the fluid that fills the spaces between cells
  • has the same composition as plasma with no plasma proteins and rbcs
28
Q

What is oncotic pressure?

A
  • the tendency of water to move into the blood by osmosis (-3.3 kPa)
29
Q

What is hydrostatic pressure?

A
  • the pressure exerted by blood in an enclosed system (blood vessels)
30
Q

How is tissue fluid formed?

A
  • since plasma proteins cannot pass through capillary walls, they give the blood a low water potential
    • this causes water to move into the blood in capillaries (from arterioles)
      ‎
  • arterial end:
    • hydrostatic pressure = 4.6 kPa
    • higher than onc. pressure, so fluid is squeezed out (tissue fluid)
      ‎
  • venous end:
    • hydrostatic pressure = 2.3 kPa
    • lower than onc. pressure
    • water moves back into capillaries
    • 90% of the tissue fluid is back into blood vessels
31
Q

What is lymph?

A
  • 10% of the liquid that leaves the blood vessels and drains into lymph capillaries
  • similar in composition to plasma/tissue fluid but has less oxygen/nutrients
  • contains fatty acids
32
Q

What are lymph vessels?

A
  • joined up lymph capillaries which transport the. lymph
  • contain one-way valves to prevent backflow
  • ** lymph returns to blood (into the clavicle veins) **
33
Q

What are lymph nodes?

A
  • small glands that can contain lymphocytes that produce antibodies
  • they intercept bacteria (ingested by phagocytes)
  • enlarged lymph nodes are a sign that the body is fighting off an invading pathogen
34
Q

How is oxygen transported?

A
  • erythrocytes contain haemoglobin which carry O2
    • haemoglobin is a large globular conjugated protein
  • O2 binds loosely to haemoglobin forming oxyhaemoglobin (reversible)
  • steep conc. gradient between lungs (high O2) and erythrocytes (low O2)
    • O2 moves in and binds with haemoglobin
    • since free O2 levels are low, steep conc. gradient is maintained
35
Q

What is the oxygen dissociation curve?

A
  • percentage saturation haemoglobin plotted against partial pressure of oxygen
    • high partial pressure = haemoglobin is rapidly loaded with O2
36
Q

What is the Bohr effect?

A
  • as partial pressure of CO2 rises, haemoglobin gives up oxygen more easily
  • active tissue = haemoglobin gives up O2 more easily
37
Q

What is fetal haemoglobin?

A
  • higher affinity for O2 than adult haemoglobin as they will jot receive enough O2
38
Q

How is carbon dioxide transported?

A
  • react slowly with water to form carbonic acid
  • this then dissociates and forms H ions and hydrogen carbonate ions
    • carbonic anhydrase catalyses this reaction
39
Q

What is chloride shift?

A
  • when the negatively charged hydrogen carbonate ions move out of the erythrocytes into the plasma, chloride ins move into the cells
  • this maintains the electrical balance of the cell
40
Q

What does the heart consist of ?

A
  • it is made of a cardiac muscle
  • four chambers and two pumps
    • deoxygenated = right
    • oxygenated = left
      ‎
  • coronary arteries supply muscle with blood
41
Q

What is the external structure of the heart?

A
  • ** clockwise **
  • aorta (aortic arch)
  • pulmonary artery
  • pulmonary vein
  • left atrium
  • left ventricle
  • (descending aorta)
  • inferior vena cava
  • right ventricle
  • right atrium
  • superior vena cava
42
Q

What is the internal structure of the heart?

A
  • pulmonary veins
  • left atrium
  • bicuspid valve (left atrioventricular/tendinous cords)
  • left ventricle (thick muscular wall)
  • semilunar valves
  • aorta
    ‎
  • vena cava
  • right atrium
  • tricuspid valve (right atrioventricular/tendinous cords)
  • right ventricle
  • semilunar valves
  • left pulmonary artery
43
Q

What is the movement of deoxygenated blood through the heart?

A
  • enters the right atrium from the vena cava (inferior = lower body, superior = upper body) at a low pressure
  • pressure builds as blood flows in
  • tricuspid valve opens to allow blood to flow into the right ventricle
  • the valve then closes to prevent backflow
  • right ventricle contracts and pumps the blood through the semilunar valves
  • the blood is sent through the pulmonary artery
  • this transports it to the capillary beds of the lungs
44
Q

What is the movement of oxygenated blood through the heart?

A
  • enters the left atrium from the pulmonary vein
  • as pressure builds, bicuspid valve opens and allows blood to enter the left ventricle
  • valve closes to prevent backflow
  • left ventricle then contracts and pumps the blood through the semilunar valves
  • it then enters the aorta and is pumped around the body
45
Q

Why is the muscular wall of the left side much thicker than the right?

A
  • the lungs are relatively close to the heart and are much smaller than the rest of the body
    • so the right ventricle pumps the blood a relatively short distance
    • it only has to overcome the resistance of pulmonary circulation
  • the left ventricle has to overcome the resistance of the aorta and the arterial systems of the whole body
    • blood must also be pumped under pressure to all areas of the body
46
Q

What is the septum?

A
  • inner dividing wall of the heart
  • prevents the mixing of deoxygenated and oxygenated blood
  • allows for efficient supply of oxygen around the body
47
Q

What is the cardiac cycle?

A
  • the events that take place in a single heartbeat
  • this lasts about 0.8 seconds in an adult
48
Q

What is diastole?

A
  • the heart relaxes
  • atria then the ventricles fill with blood
  • volume and pressure of blood in the heart build as the heart fills
  • pressure in the arteries is at a minimum
49
Q

What is systole?

A
  • when the atria contract (atrial systole) and then the ventricles contract (ventricular)
  • increases the pressure inside the heart
  • this forces out the blood from the right (lungs) and the left (body)
  • volume and pressure of blood in heart are low at the end of systole
  • pressure in the arteries are at a maximum
50
Q

What is the cardiac output equation?

A
  • cardiac output = heart rate x stroke volume
51
Q

What happens to aortic pressure?

A
  • rises when the ventricles contract
  • then gradually falls (never falls below 12kPa due to its elasticity)
  • recoil produces a slight rise in pressure at the start of the relaxation phase
52
Q

What happens to atrial pressure?

A
  • always relatively low due to thin walls (less force)
  • highest when contracting
  • pressure builds when atria fill with blood until atro-ventricular valve opens
53
Q

What happens to ventricular pressure?

A
  • low at first, gradually increases when ventricles fill with blood
  • atrioventricular valves close and pressure rises (thick walls contract)
  • as pressure rises above the aorta’s, blood is forced into it
  • pressure falls as ventricles empty
54
Q

What happens to ventricular volume?

A
  • rises as the atria contract and ventricles fill with blood
  • drops suddenly as blood is forced out into aorta
55
Q

What is the lub-dub sound?

A
  • lub = blood forced against the atrio-ventricular valves (closes) as ventricles contract
    ‎
  • dub = blood closes the semilunar valves as ventricles relax
56
Q

Why is the cardiac muscle myogenic?

A
  • it is able to initiate its own contractions without the need for nervous stimulation
    • the average resting heart rate of an adult is around 70 bpm
57
Q

How is heart action initiated and coordinated?

A
  • the sino-atrial node (SAN) initiates the electrical activity in the atria
  • causes them to contract, starts the heartbeat
    ‎
  • it is picked up by the atrio-ventricular node (AVN) which causes a slight delay
  • the electrical wave then stimulates the bundle of His (consisting of Purkyne fibres)
    • they go through the septum
      ‎
  • the bundle of His splits into two branches and sends a wave of excitation down to the apex
    ‎
  • at the apex, the Purkyne fibres spread through the ventricle walls
  • this triggers the contraction of the ventricles
58
Q

What is an ECG?

A
  • electrocardiogram
  • measures the electrical differences in the skin which result from the heart’s electrical activity
    • they can be used to help diagnose heart problems (treated correctly/fast)
59
Q

What is tachycardia?

A
  • very rapid heartbeat (over 100 bpm at rest)
  • abnormal if caused by problems in electrical control of the heart
  • treated by medication/surgery
60
Q

What is bradycardia?

A
  • slow heartbeat (below 60 bpm)
  • fitness/training can cause this as heart beats more slowly and efficiently
  • severe cases require an artificial pacemaker
61
Q

What is ectopic heartbeat?

A
  • extra heartbeats that are out of the normal rhythm
  • mostly have it at least once a day
  • can be serious if it is very frequent
62
Q

What is atrial fibrillation?

A
  • example of arrhythmia (abnormal rhythm of the heart)
  • rapid electrical impulses are initiated in the atria
  • fibrillate up to 400 times a min
    • but it does not allow for proper contractions
    • heart does not pump blood around very effectively

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