Transport in animals Flashcards
1
Q
3.1.2 a)
Why don’t single-celled organisms need transport systems?
A
processes such as; diffusion, osmosis, active transport, endocytosis and exocytosis can supply everything the cell needs to import/export
BUT WHY??
- Metabolic demand = Low
- smaller organisms = less active
- Smaller size = molecules, food, waste, etc. have short distances to travel
- shorter diffusion pathway
- SA:V ratio = High
- more SA for capacity of the organism = supplies organisms demand
2
Q
3.1.2 a)
What is the need of transport systems in multicellular animals?
A
important processes such as; diffusion, osmosis, active transport, endocytosis and exocytosis are not enough to supply the organism
BUT WHY??
- Metabolic demand = High
- lots of O2 + food required, lots of waste produced
- Long distances for stuff to travel (size of animal)
- increased diffusion pathway
- SA:V ratio = Low
- amount of SA to absorb/remove substances is too small for capacity of animal
3
Q
List the different types of circulatory systems?
A
- Open systems
- Closed systems:
- Single closed system
- Double closed system
4
Q
3.1.2 b)
Describe an open circulatory system
A
- Very few (open ended) vessels
- Hameolymph enters heart through pores called ostia then pumped towards head by peristalsis
- Haemolymph comes into direct contact with tissues and cells (body cavity bathed in haemolymph) = this is where food and nitrogenous waste products are exchanged between haemolymph and tissues
- Haemolymph pours straight into the haemocoel of the insect where it is then under low pressure
5
Q
3.1.2 b)
What is insect blood called?
A
- Haemolymph - transport medium
- doesn’t carry O2 or CO2
- gas exhchange takes place in the tracheal system
- transports food, nitrogenous waste, and cells involved in defending against disease
- doesn’t carry O2 or CO2
6
Q
3.1.2 b)
What is the body cavity of an insect called?
A
- Haemocoel
- body cavity - is split by a membrane
7
Q
3.1.2 b)
What organisms are open-ended circulatory systems found in?
A
- Mainly invertabrate animals
- including most insects
- some molluscs
8
Q
3.1.2 b)
Where is the heart in an insect?
A
- Heart (long muscular tube) extends along the length of thorax and abdomen, lies just under the dorsal (upper) surface of the body
- Haemolymph travels through heart then dorsal aorta (open-ended vessel)
9
Q
3.1.2 b)
What are the disadvantages of an open circulatory system?
A
- Haemolymph circulates but steep diffusion gradients cannot be maintained for efficient diffusion
- Amount of haemolymph flowing to a particular tissue cannot be varied to meet changing demands
- Blood pressure = low
- Blood flow = slow
10
Q
3.1.2 b)
How is a closed circulatory system different to an open circulatory system?
A
- Blood enclosed in blood vessels
- Blood doesnt come into direct contact with other cells in the body
- separate fluid (tissue fluid) bathes tissues + cells
- Heart pumps blood around the body under higher pressure and relatively quickly
- therefore faster delivery of O2 and nutrients
- faster removal of CO2 and waste
- Substances enter/leave blood by diffusion through walls of blood vessels
- Amount of blood flowing to a particular tissue can be adjusted by widening/narrowing blood vessels
- vasodilation/vasoconstriction
- Most closed circulatory systems contain blood pigment (e.g. haemoglobin) that carries O2/CO2
11
Q
3.1.2 b)
What organisms are closed circulatory systems found in?
A
- Found in many different phyla
- echinoderms
- starfish, sea urchins etc.
- cephalopod molluscs
- octopods, squid etc.
- annelid worms
- common earthworm etc.
- All vertebrate groups
- including mammals
- echinoderms
12
Q
3.1.2 b)
What organisms are single closed circulatory systems found in?
A
- Fish
- Annelid worms (e.g. common earthworm)
13
Q
3.1.2 b)
Describe the single closed circulatory system?
A
- Blood travels once through the heart for each complete circulation of body
- Blood passes through 2 sets of capillaries before returning to the heart
- for fish:
- first: capillaries in gills = exchanges O2 and CO2
- second: capillaries in the rest of the body = substances exchanged between blood and cells
- passing through 2 ses of capillaries = low blood pressure due to capillaries being narrow
- results in blood getting back to heart quite slowly = limits efficiency of exchange processes => activity level of animal = Low
14
Q
3.1.2 b)
Why are fish active even though they have a single closed circulatory system?
A
- single closed circulatory system is sufficient for fish demand
- countercurrent gaseous exchange mechanism in their gills = lots of intake of O2 from water
- Reduced metabolic demands due to:
- Body weight supported by water
- Do not maintain their own body temp oC
15
Q
3.1.2 b)
What organisms are a double closed circulatory system found in?
A
- Active land animals
- large + high metabolic demand
- Birds
- Most mammals
- large + high metabolic demand
16
Q
3.1.2 b)
What are the features of a good transport system?
A
- medium - carry nutrients, O2 and waste around body
- pump to create pressure - push fluid around body
- exchange surfaces - allowing substances to enter/leave blood
- tubes/vessels - carry fluid by mass flow
- two circuits - one to pick up O2, one to deliver to tissues
17
Q
3.1.2 b)
Describe a double closed circulatory system
A
- Blood travels twice through the heart for each circuit of the body
- Blood pumped from heart to lungs to pick up O2 and remove CO2 then back to heart (pulmonary circuit)
- Blood pumped all around body then back to heart (systemic circuit)
- each circuit only travels through one capiliary network
- relative high blood pressure and fast blood flow can be maintained
18
Q
3.1.2 e) i)
What is the heart?
A
- organ (made up of cardiac muscle)
- moves blood around the body
19
Q
3.1.2 e) i)
What external structures/features does the heart have?
A
- coronary artery
- cardiac vein
- inelastic pericardial membranes
20
Q
3.1.2 e) i)
What are the four chambers of the heart?
A
- consists of 4 chambers
- left ventricle
- pumps blood to the systemic circuit via aorta
- right ventricle
- pumps blood to the pulmonary circuilt via pulmonary artery
- left atrium
- filled with blood from systemic circuit via vena cava
- right atrium
- filled with blood from the pulmonary circuit via pulmonary vein
21
Q
3.1.2 e) i)
What are the structures/features of the heart?
A
- attached to each valve inside the heart are tendinous cords
- these prevent valves from turning inside out during ventricular systole (ventricle contractions)
22
Q
3.1.2 e) i)
What is the purpose of the inelastic pericardial membranes?
A
- Help prevent the heart from over-distending with blood (AKA filling up too much)
23
Q
3.1.2 e) i)
What are the issues associated with blockages in the coronary arteries?
A
- Heart is a hardworking organ
- vital for its muscle cells to get a constant supply of oxygenated blood and for its waste products to be removed
- If coronary artery gets blocked
- e.g. from a fatty diet, and a build up of low density lipids in the artery
- Amount of O2 and nutrients delivered to the heart will be reduced
- Patient may experience serious consequences
- angina (severe heart pain)
- heart attack (myocardial infarction)
24
Q
3.1.2 e) i)
What is the purpose of the septum?
A
- Seperates the left and right ventricle
- ensures that oxygenated blood in the left ventricle and deoxygenated blood in the right ventricle do not mix
25
**3.1.2 e) i)**
Explain the variation in thicknesses of the chambers in the heart?
* Left ventricle
* wall of left ventricle usually 2 to 3 times thicker than right ventricle
* needs to be thicker
* because oxygenated blood in left ventricle is pumped through aorta (blood in arteries under higher pressure than veins)
* and under a high pressure, because it has to travel a longer distance and needs to overcome the resistance of the systemic circulation
* Right ventricle
* wall of right ventricle is thicker than the walls of the atria
* higher pressure than the atria, because ventricles pump blood through arteries, not recieving through veins
* right ventricle pumps deoxygenated blood to lungs
* and lungs are in the chest cavity close to the heart meaning not a long distance needs to be covered
* therefore doesnt need to be as high a pressure as left ventricle, especially because alveoli are delicate and may be damaged by a high blood pressure
* Atria
* thinner muscle walls
* do not need high pressure, because main purpose is to recieve blood from veins
26
**3.1.2 f)**
What does it mean to describe the heart as a myogenic muscle?
* muscle that can initiate its own contractions
* (pacemaker)
27
**3.1.2 e) i)**
Describe the structure of the cardiac muscle?
* consists of fibres that branch
* this produces cross bridges (see middle of micrograph)
* help to spread stimulus around the heart, and ensure that muscle produces squeezing action rather than simple reduction in length
* lots of mitochondria between muscle fibrils (myofibrils)
* to supply energy for contractions
* muscle cells seperated by intercalated discs (thick wavy blue line)
* facilitate synchronised contraction
* each cell has a nucleus and is divided into contractile units called sarcomeres (thin blue lines)
28
**3.1.2 b)**
How does an open circulatory system differ in larger and more active insects?
* (e.g) locusts
* Have open ended tubes attached to the heart
* to direct blood towards more active parts of the body e.g. legs and wings
29
**3.1.2 a)**
What are the three main factors that influence the need of a transport system?
* size
* SA to V ratio
* level of metabolic activity
30
**3.1.2 a)**
Why do waste products need to be removed?
* If waste not removed
* there will be a build up of waste
* would become toxic
31
**3.1.2 a)**
Give specific examples of how size influences the need of a transport system?
* long distance to travel = increased diffusion pathway
* Molecules like hormones, enzymes = made in one place, needed in another
* Food digested in one organ system, needs to be transported cells for respiration
* Waste of metabolism needs to be transported from cells to excretory organs
32
**3.1.2 b)**
Why can't the blood in the pulmonary circuit be as high as blood flowing through the systemic circuit?
* if blood pressure is too high in pulmonary circuit, could damage delicate capiliaries in lungs
33
**3.1.2 b)**
**advantages of double closed circulatory system?**
34
**3.1.2) b)**
What are the disadvantages of a single closed circuit in comparison to a double closed circuit?
* blood pressure drops because blood passes through two sets of capiliares
* blood has a low pressure as it flows towards body = will not flow as quickly
* rate at which O2 + nutrients are delivered to respiring tissues and CO2 + urea removed, is limited.
35
**3.1.2 c)**
What are arteries?
* vessels that carry blood away from the heart
* under higher pressure than veins
36
**3.1.2 c)**
What are arterioles?
* small vessels that distribute blood from an artery to the capillaries
37
**3.1.2 c)**
What are capillaries?
* very small vessels with very thin walls
38
**3.1.2 c)**
What are venules?
* small blood vessels that collect blood from capillaries and lead into veins
39
**3.1.2 c)**
What are veins?
* vessels that carry blood back to the heart
40
**3.1.2 c)**
What are some examples of components utilised in some blood vessels?
* Elastic fibres - composed of elastin and can stretch and recoil (elastic recoil), providing vessel walls with flexibility
* smooth muscle - contracts or relaxes, changing the size of the lumen (channel within blood vessel)
* collagen - provides structural support to maintain volume and shape of vessel (prevent it from collapsing)
* endothelium - single layer of endothelial cells, is smooth, to reduce friction with flowing blood
41
**3.1.2 c)**
Which artery carries oxygenated blood and which carries deoxygenated blood?
* pulmonary artery carries deoxygenated to lungs
* systemic arteries (e.g. aorta) oxygenated to rest of body
* during pregnancy - umbilical artery, carries deoxygenated blood from fetus to placenta
42
**3.1.2 c)**
Describe the structure and function of an artery
* artery carries blood away from heart
* lumen = relatively small --\> to maintain high hydrostatic pressure
* artery wall = thick --\> withstand high hydrostatic pressure
* artery wall = 3 layers
* tunica interna/intima = thin layer of elastic tissue = allows wall to stretch and recoil (elastic recoil) within limits (maintained by collagen) --\> maintain high hydrostatic pressure and take larger volume of blood
* inner wall = folded to allow lumen to expand when blood flow = increased
* tunica media = thick layer of smooth muscle = contracts/relaxes -\> changes lumen size
* tunica externa/adventita = thick layer of collagen and elastic tissue --\> provides strength for high hydrostatic pressure and recoil = to maintain pressure
* inside lined with endothelium (endothelial cells) reduces friction with flowing blood
43
**3.1.2 c)**
Describe how it is possible to feel ones own pulse
* pulse = surge of blood when heart contracts
* elastic fibres reduce effects but cannot get rid of completely
* reduced by elastic recoil which returns fibres to original length
* to give continuous flow
44
**3.1.2 c)**
Describe the structure and function of arterioles
* arterioles = small blood vessels
* distribute blood from artery to capillaries
* more smooth muscle + less elastin in walls than arteries
* layer of smooth muscle - can contract/dilate to vary lumen size
* contraction of smooth muscle = vasoconstriction
* smaller lumen = increased resistance + reduces rate of blood flow (preventing blood flowing into a capillary bed)
* can be used to divert flow of blood to regions in need of more O2
* relaxation = vasodilation, therefore blood flows into capillary bed
45
**3.1.2 c)**
What is an aneurysm?
* bulge or weakness in blood vessel
* most common places: aorta and arteries in the brain
* can be fatal
* factors that can increase risk
* high blood pressure
* potentially if ratio of collagen to elastin is increased
46
**3.1.2 c)**
Describe the structure and function of capillaries?
* link arterioles to venules
* very thin walls - allow for diffusion between blood and tissue fluid
* walls consist of a single layer of flattened endothelial cells - reduces diffusion distance for exchanging materials
* (for most areas of body) gaps between endothelial cells = relatively large
* except CNS system (tight junctions between cells)
* therefore walls = leaky, allowing blood plasma and dissolved substances to leave blood
* narrow lumen = one red blood cell thick (cell has diameter of 7µm)
* large SA for diffusion
* total cross sectional area of capillary \> than arteriole = rate of blood flow falls - (relatively slow movement) allowing time for exchange
47
**3.1.2 c)**
Describe the structure and function of a venule?
* collect blood from capillary bed - lead into veins
* venule wall consists of
* thin layers of smooth muscle
* elastic tissue outside endothelium
* thin outer layer of collagen
* several venules join to form a vein
48
**3.1.2 c)**
What are the two main vessels carrying deoxygenated blood back to the heart?
* superior vena cava - from head + upper body
* inferior vena cava - from lower parts of body
49
**3.1.2 c)**
Why is the relative pressure in the veins very low?
* do not have a pulse
* surge from heart = lost after blood passes through narrow capillaries
* however large reservoir of blood
* 60% of blood in your veins at any one time
50
**3.1.2 c)**
Describe the structure and function of a vein.
51
**3.1.2 d)**
What is the main transport medium of human beings?
* Blood - enclosed in vessels
* contains a yellow liquid = plasma
* contains cells (eg. red blood cells and white blood cells)
* red blood cells = erythrocytes
* white blood cells = leucocytes
* contains platelets
52
**3.1.2 d)**
What does plasma contain?
* plasma makes up 55% of the blood by volume (most of that percentage = water)
* O2 and CO2
* dissolved glucose
* amino acids
* mineral ions
* hormones
* plasma proteins (e.g. albumin)
* fibrinogen
* globulins
53
**3.1.2 d)**
What is albumin important for?
* for maintaining the osmotic potential of blood
54
**3.1.2 d)**
What is fibrinogen important for?
* blood clotting
55
**3.1.2 d)**
What are globulins involved in?
* transport and immune system
56
**3.1.2 d)**
What do red blood cells do?
* carry O2 to the cells
* give blood its red appearance
57
**3.1.2 d)**
What are platelets?
* fragments of large cells called megakaryocytes
* cells found in the red bone marrow
* involved in the clotting mechanism of the blood
58
**3.1.2 d)**
What does the blood transport?
main functions of blood
* maintain steady body temperature
* acts as a buffer (minimising pH changes)
* transport
**_But transport of what??_**
* O2 to respiring cells
* CO2 from respiring cells
* digested food from small intestine
* nitrogenous waste from cells to excretory organs
* hormones (chemical messages/signals)
* food molecules from storage compounds to cells that need them
* platelets to damaged areas
* cells and antibodies involved in the immune response
59
**3.1.2 d)**
What is tissue fluid?
* the fluid that fills spaces between cells and tissues (bathes cells + tissues)
* comes into direct contact and supplies tissues with O2 and other nutrients
* exchange of nutrients occurs across plasma membrane by diffusion, facilitated diffusion and active uptake (O2 enters, CO2 leaves cells)
* formed by plasma leaking from the capillaries
* CO2 and other waste products carried back into capillary
* when some of the tissue fluid returns to capillary
60
**3.1.2 d)**
What is oncotic pressure?
* pressure created by the osmotic effects of the solutes
61
**3.1.2 d)**
What is hydrostatic pressure?
* pressure that fluid exerts when pushing against the sides of a vessel or container
62
**3.1.2 d)**
How is the composition of tissue fluid different to that of blood?
* blood plasma leaks through the capillaries
* carries all the disolved substances
* red blood cells, white blood cells, platelets and plasma proteins (particularly albumin) remain in blood
* too big to pass through gaps in capillary wall
63
**3.1.2 d)**
How does plasma leave the capillaries?
* through gaps in the capillary wall
* process called mass flow (not diffusion)
64
**3.1.2 e)ii)**
What heart is commonly used in dissection?
* sheep or pig
* similar shape and size to a human heart
65
**3.1.2 e)ii)**
What do you have to be aware of when drawing a heart?
* hearts obtained from butcher = not always intact
* major blood vessels cut off
* atria often remove
* because people don't want to eat all the tubes
66
**3.1.2 e)ii)**
What can be easily identified from the external view of a heart?
* coronary arteries
* supply the heart muscle with blood needed to beat
* narrowing or blockage in coronary arteries causes symptoms of coronary heart disease or even heart attacks
67
**3.1.2 h)**
What can be interpreted from the following ECG?
* sinus rhythm
* Normal ECG - no abnormalities
* beats evenly spaced
* rate between 60-100/min
68
**3.1.2 h)**
What can be interpreted from the following ECG?
* bradycardia
* slow heart rate
* beats evenly spaced
* rate \< 60/min
* many people have bradycardia because of being fit
* training makes heart beat more slowly + effectively
* severe bardycardia can be serious
* may need artificial pacemaker to keep heart beating steadily
69
**3.1.2 h)**
What can be interpreted from the following ECG?
* tachycardia
* fast heart rate - very rapid
* beats evenly spaced
* rate \> 100/min
* often normal
* e.g. after exercise, during fever, when frightened or angry
* if abnormal may be caused by problems in the electrucal control of the heart and may need to be treated by medication or surgery
70
**3.1.2 h)**
What can be interpreted from the following ECG?
* ectopic heartbeat
* altered rhythm
* extra (early/ectopic) ventricular beat
* followed by longer than normal gap before the next beat
* most people have at least one a day
* usually normal - but can be linked to serious conditions if very frequent
* patient often feels as if a heartbeat has been missed
71
**3.1.2 h)**
What can be interpreted from the following ECG?
* Atrial fibrillation
* irregular rhythm of atria - beating more frequently than ventricles - no clear P wave seen
* ventricles lose regular rhythm
* example of arrhythmia - means an abnormal rhythm of heart
* rapid electrical impulses are generated in the atria
* they contract very fast (fibrillate) up to 400 times a minute - but do not contract properly and only some of the impulses are passed on to the ventricles which contract much less often
* as a result - heart does not pump blood effectively
72
**3.1.2 h)**
What is an electrocardiogram?
* a trace that records and monitors the electrical activity of the heart
* doesn't directly measure electrical activity of heart
* instead number of electrode sensors painlessly attached to clean skin (to get good contact needed for reliable results)
* measures tiny differences in skin
* resulting from electrical activity generated by heart that spreads through tissues near heart and outwards to skin
* sensors pick up electrical excitation created by heart and this signal is fed into a machine that converts it into a trace
73
**3.1.2 h)**
Why is an ECG useful?
* ECG - used to help diagnose heart problems
* e.g. patient with heart attack
* recognisable changes take place in the electrical activity of heart
* diagnosis leads to problems being treated correctly and quickly
74
**3.1.2 h)**
Describe the shape of the trace of a healthy persons electrocardiogram?
* consists of a series of waves that are labelled P,Q,R,S,T
* wave P shows the excitation of the atria
* QRS indicates the excitation of the ventricles
* T shows diastole
75
**3.1.2 i)**
How are erythrocytes adapted to their main function?
* erythrocytes (red blood cells) = very specialised
* main function - transporting O2 from lungs to cells of the body
* also involved in removal of CO2 from cells to the lungs for gaseous exchange
* biconcave shape
* has a larger surface area than simple disc or sphere structure, for diffusion of gases
* also helps to pass through narrow capillaries
* in an adult
* erythrocytes continuously formed in red bone marrow
* when mature erythrocytes enter circulation, they have lose their nuclei
* maximises amount of haemoglobin that fits into the cells
* also limits their life - last about 120 days in blood stream
76
**3.1.2 i)**
What is haemoglobin?
* the red pigment that carries O2 and gives erythrocytes their colour
* a large complex globular conjugated protein with four subunits
* each subunit consists of a polypeptide chain and a haem (non-protein) prosthetic group
* each haem group contains a single iron ion (Fe2+)
* iron ion can attract and hold O2 molecule
* there are around 280 - 300 million haemoglobin molecules in each red blood cell
* each haemoglobin molecule can bind to 4 O2 molecules
* because each haem group can associate with one O2 molecule
77
**3.1.2 i)**
What does affinity mean?
* a strong attraction
* the haem groups in haemoglobin are said to have a high affinity for O2
78
**3.1.2 i)**
What happens to haemoglobin when it associates with O2?
* O2 binds quite loosely to haemoglobin
* forming oxyhaemoglobin
* the reaction is reversible
Hb + 4O2 ⇌ Hb(O2)4
Hb = haemoglobin
O2 = oxygen
Hb(O2)4 = oxyhaemoglobin
79
80
**3.1.2 j)**
How is fetal haemoglobin different to adult haemoglobin?
* fetal haemoglobin has a higher affinity for O2 than adult haemoglobin
* at every point along the dissociation curve, fetal haemoglobin is to the left
