CHAPTER 8 - TRANSPORT IN ANIMALS Flashcards
1
Q
Why do animals need specialised exchange systems
A
Greater distances to inner core - diffusion would be too slow
2
Q
Why are Specialised transport systems needed
A
Metabolic demand of most multicellular animals are high (so diffusion over the long distances cannot support an organism)
SA:V gets smaller as multicellular organisms get bigger so not only do the diffusion distances get bigger, but the amount of SA available to remove substances becomes relatively smaller
Molecules, such as hormones or enzymes 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 and other aspects of metabolism
Waste products of metabolism need to be removed from the cells and transported to excretory organs
3
Q
What are common features of a circulatory system
A
They have liquid transport medium that circulates around the system (eg. blood)
They have vessels that carry the transport medium
They have a pumping mechanism to move the fluid around the system
4
Q
What is a mass transport system
A
Substances are transported in a mass of fluid with a mechanism for moving the fluid around the body
5
Q
What is an open circulatory system
A
When the blood is pumped straight from the body cavity of the animal
(pg 175)
6
Q
What is the open body called in an open circulatory system
A
Haemocoel
7
Q
Does Haemocoel have high or low pressure
A
Low pressure - which comes into direct contact with the tissues and cells
8
Q
What is insect blood called
A
Haemolymph
9
Q
What are some animals that have open-ended circulatory systems
A
Invertebrates, insects and molluscs
10
Q
What does Haemolymph transport
A
Food and nitrogenous waste products and the cells involved in the defense against the disease
Doesnt carry oxygen or carbon dioxide
11
Q
How does the blood return to the heart in an open circulatory system
A
Open-ended vessel
12
Q
What is the body cavity split by
A
A membrane and the heart extends along the length of the thorax and the abdomen of the insect
13
Q
What is the issue with haemolymph
A
It circulates but steep diffusion gradients cannot be maintained for efficient diffusion,
The amount of haemolymph flowing to a particular tissue cannot be varied to meet changing demands
14
Q
What is a closed circulatory system
A
Where blood is enclosed in blood vessels and doesnt directly come into contact with the cells of the body
Blood is pumped by the heart around the body under pressure and relatively quickly, then returns to the heart
15
Q
How do substances leave and enter the blood in a closed circulatory system
A
Diffusion through the walls of blood vessels
16
Q
What are features of a closed circulatory system
A
Blood flowing to particular tissue can be adjusted by widening or narrowing blood vessels
Contain blood pigments which carry respiratory gases
17
Q
What are echinoderms
A
Animals such as sea urchins and starfish - any variety of invertebrate marine animals belonging to the phylum echinodermata, which have a hard covering or skin
18
Q
What animals have a closed circulatory system
A
Echinoderms, cephalopod molluscs, octopods, squid, most worms, and all vertebrates, including mammals
19
Q
What organisms have a single closed circulatory system
A
Fish and annelid worms
20
Q
What is a single-closed circulatory system
A
Where the blood flows through the heart and is pumped out to travel all around the body before returning to the heart
21
Q
What happens in the capillaries of a closed circulatory system
A
In the first set, they Exchange oxygen and carbon dioxide
In the second set, substances are exchanged between the blood and cells
This also leads to a drop in blood pressure and a slow return to the heart (and quite a slow exchange)
22
Q
Why do fish have a relatively efficient single circulatory system
A
They have a counter current gaseous exchange mechanism in their gills that allows them to take a lot of oxygen from the water.
The body weight is supported by the water in which they live so do not maintain their own body temperature.
This reduces the metabolic demands on their bodies are combined with efficient gas exchange explains how fish can be so active with a single close circulatory system.
23
Q
What are the two circuits in a double circulatory system?
A
Blood is pumped from the heart to the lungs to pick up oxygen and unload carbon dioxide, then returns to the heart - pulmonary circulation
Flows from the heart, and his pumped out, travel all around the body before returning to the heart again - Systemic circulation
This means the blood travels twice through the heart for each one circuit of the body and only passes to one capillary network, so it is high pressure and the fast flow blood can be maintained
(pg 177)
24
Q
The function of a circulatory system
A
Transports requirements for metabolism, e.g., oxygen, food molecules, to cells
removes waste products of metabolism from cells and carries them to excretory organs
transports materials made in one place to another place where they are needed
25
Explain why circulatory systems are found in multicellular organisms, but not in unicellular organisms
Unicellular organisms have large SA : V ratio so diffusion distances small and metabolic demands low
so diffusion can supply and remove substances quickly and efficiently enough
Multicellular organisms have small SA : V ratio, so long diffusion distances. Metabolic demands are high – diffusion alone can no longer supply all needs quickly and efficiently enough
26
Compare open and closed circulatory systems
Similarities:
liquid transport medium, vessels to transport the medium,
pumping mechanism to move transport fluid around system
Differences:
open has few vessels; closed has transport medium (blood) enclosed in vessels,
In open transport medium is pumped into body cavity (haemocoel) under low pressure; in closed heart pumps blood around body under pressure
In open, transport medium is in direct contact with body cells; in closed transport medium has no direct contact with body cells,
In open transport medium returns to heart through open ended vessel; in closed blood flows relatively fast and returns to heart all within vessels
27
Land predators such as foxes have a double closed, circulatory system. Aquatic practices such as Pike are effective with a single close circulatory system. Explain why these two types of predator have different circulatory systems.
Land predators top land predators hunt so need ability to move in fast bursts
they grow large and maintain own body temperature
need to support body against gravity
they may be pregnant and so have to support needs of growing fetus as well as own body needs high metabolic rate
they need a very efficient circulatory system supply. Double circulatory system supplies blood to lungs to be oxygenated and then returns it to heart to be pumped around body
so tissues receive a high level of oxygen and high levels of carbon dioxide
can be removed.
Aquatic predators such as pike need to hunt so also need efficient circulatory system
their single system less efficient than a double system but bony fish have operculum so continuous flow of water over gills to oxygenate blood countercurrent flow allows efficient oxygen uptake
they do not maintain their own body temperature and are supported by water
so demands of tissues much lower than those of an animal like a fox
so single circulation is adequate to supply their needs
28
What are some different components and uses in a blood vessel
Elastic fibres - composed of elastin and can stretch and recoil, providing vessel walls with flexibility
Smooth muscle - contracts or relaxes, which changes the size of the lumen
Collagen - provides structural support to maintain the shape and volume of the vessel
29
What are the job of arteries
Carry blood AWAY from heart and INTO organs/tissues of the body
30
What are the only two arteries which dont carry oxygenated blood
Pulmonary artery - deoxygenated from heart to lungs
Umbilical Artery - deoxygenated blood from foetus to placenta
31
What do arterioles do
link arteries and capillaries
32
What is the structure of an artery
Inside to out -
Lumen, Endothelium, elastic layer, muscle layer, collagen layer
(pg 178 & 179)
33
What do the arterioles do in vasoconstriction
Smooth muscle will contract and constricts the blood vessel, preventing blood flowing into a capillary bed
34
What do the arterioles do during vasodilation
Smooth muscle in arteriole wall relaxes, blood flows into capillary bed
35
What are the proportions of components in the artery wall
Page 179
36
What do capillaries do
Microscopic blood vessels that link the arterioles with the venules
37
How are capillaries adapted for their role?
Provide a very large surface area for the diffusion of substances into and out of the blood
The total cross-sectional area of the capillaries is always greater than the arterial supply, and then, so the rate of blood flow falls. The relatively slow movement of blood through capillaries gives more time for the exchange of materials by diffusion between the blood and the cells
The walls are a single endothelial cell thick, giving a very thin layer for diffusion
Small lumen, so they can only fit red blood cells in single file
38
What are the proportions of components in the vein wall
page 181
39
What do veins do
Carry blood away from the cells of the body, and towards the heart, and almost always carry deoxygenated blood (with two exceptions)
40
Why do vein walls not contain much elastin and muscle?
Blood pressure is very low compare with the arteries and they do not have a pulse of surges from the heart are lost. Therefore do not have to do with high blood pressure
41
What do venules do?
Link capillaries with the veins
42
How are veins adapted to their function?
Majority of veins have one-way valves intervals. These are flaps are infoldings of the inner lining of the vein, so when blood flows in the direction of the heart, the valves open and passed through if the blood starts flow backwards, the valves close preventing us from happening.
Many bigger veins run between the big active muscles in the body. For example, in the arms and legs. When the muscles contract, they squeeze the veins, forcing the blood towards the heart, valves preventing backflow in the muscle relaxes
Breathing movements of the chest acts as a pump. The pressure changes and squeezing actions Move blood in the veins of the chest and abdomen towards the heart
43
Veins have valves but arteries do not. Explain why
Arterial blood under pressure from pumping of blood and elastic recoil of artery walls, so no tendency for it to flow backwards (1).
After passing through capillary beds blood in veins under much lower pressure, there is no pumping from heart and little elastic recoil in veins so blood might flow backwards
as it moves back towards heart against gravity. Valves prevent this happening – they open as blood flows towards heart and close if it flows in opposite direction
44
Structure of an arterial is different from the structure of an artery. Describe the differences in structure and explain how they are related to the functions of the vessels.
Arterioles have more smooth muscle and less elastin in walls than arteries, as they have little pulse surge
smooth muscle means they can constrict or dilate to control flow of blood into individual organs by preventing blood flowing into a capillary bed (vasoconstriction) or allowing it to flow (vasodilation)
45
Explain how the different structures of large veins, medium veins and venues are related to their functions in the body
Large veins have thin walls as don't have to withstand high pressures of arterial system large lumen as they contain large volume of blood
smooth muscle in veins contracts/ relaxes allowing constriction/dilation to change amount and pressure of blood
walls contain collagen and relatively little elastic fibre, so there is a limit to amount of blood that can flow through them
wide lumen and smooth lining mean blood flows easily
Medium sized veins have similar structures and function to large veins but also have valves, which prevent backflow and move it through the venous system to largest veins and so back to heart
Venules less structure in walls than veins; very thin walls with a little smooth muscle to allow blood to flow onto into veins; venules do not have valves so cannot control blood flow
46
Explain why the venules and veins in the lungs are so unusual
In all other areas of adult body veins and venules carry deoxygenated blood back from body to heart
In lungs they carry oxygenated blood from lungs back to heart
47
What are the functions of blood
Transporting:
Taking Oxygen to and carbon dioxide from respiring cells
Digested food from the small intestine
Nitrogenous waste products from the cells to the excretory organs
Chemical messengers (hormones)
Food molecules from storage compounds to the cells that need them
Platelets to damaged areas
Cells and antibodies involved in the immune response
48
What does plasma do
Carries a wide variety of components eg. dissolved glucose, amino acids, mineral ions, hormones, proteins (albumin, fibrinogen and globulins)
Transports red blood cells, white blood cells, and platelets
49
What does albumin do
Maintains the osmotic potential of the blood
50
What does Fibrinogen do
Helps in blood clotting
51
What are platelets and what do they do
Fragments of Megakaryocytes found in red bone marrow
Involved in the clotting mechanism
52
What does blood also help regulate
pH and body temperature
53
Explain how hydrostatic and oncotic pressure affect the movement of fluid into and out of the capillaries
Hydrostatic pressure is the pressure from heart beat forcing liquid out through junctions of capillary, which at arterial end of capillaries is 3.2kPa
oncotic pressure is result of water potential in capillary from plasma proteins moving water into capillary which is −2kPa
At arterial end of capillary hydrostatic pressure higher than oncotic pressure, water is forced out of capillary and forms tissue fluid
as blood moves along capillary more fluid moves out and residual force from heart beat is lost. By venous end of capillaries hydrostatic pressure has fallen to 0.5kPa
plasma proteins don’t leave capillary as they can’t pass through loose junctions so oncotic pressure is still −2kPa
as a result water now moves back into capillary by osmosis and by end of the capillary network around 90% of tissue fluid is back in capillaries again
(pg 183!!!)
54
What is lymph
Some of the tissue fluid that does not return to the capillaries, leaves the blood vessels into blind ended tubes called lymph capillaries
55
Describe briefly, the journey of lymph
Lymph exits, the blood out of the capillaries as a result of hydrostatic pressure
It does not return to the capillaries, and instead goes down a series of blind and tubes called the lymph capillaries
These capillaries join up to form larger vessels, and the fluid is transported through them by squeezing the body muscles
Backflow is prevented by valves
ALong, the vessels contain lymph nodes
Eventually, the lymph returns, the blood flowing into the right and left subclavian vein is near the collarbone
(pg 184)
56
What are lymph nodes and why are they so important?
Lymphocytes buildup in the lymph node when necessary and produce antibodies, which are then passed into the blood.
Also intercept bacteria and other debris from the length which are ingested by phagocytes found in the nodes
Enlarged lymph nodes are a sign that the body is fighting off an invading pathogen. This is why doctors office examine the neck armpits stomach, a groin of their patients which are some of the major lymph nodes.
(pg 184)
57
Describe the main functions of the blood
Transport of oxygen
and carbon dioxide (to and from respiring cells, respectively)
transport of digested food from intestine to cells
transport of nitrogenous wastes from tissues to excretory organs
transport of: hormones
platelets (for clotting)
and antibodies
immune response
maintaining constant body temperature and pH
58
Summarise the similarities and differences between plasma tissue fluid and lymph
Plasma:
straw coloured liquid which contains water, dissolved glucose and amino acids, mineral ions, hormones and large plasma proteins including albumin (important for maintaining osmotic potential of blood), fibrinogen (important in blood clotting) and globulins (involved in transport and immune system).
Tissue fluid:
Liquid contains same constituents as plasma except the plasma proteins – so no albumin, fibrinogen or globulins
Lymph:
Liquid similar to tissue fluid but with less oxygen and digested food and more carbon dioxide and waste (it has been past the cells) and more fatty acids from small intestine
59
How do erythrocytes transport oxygen
Biconcave shape, giving a larger surface area than a disc or sphere, and allows them to pass through narrow capillaries
They are continuously formed in the red bone marrow, and once they are mature, they have lost their nuclei, which maximises the amount of haemoglobin that fits into their cells, although it also limits their life
The red pigment haemoglobin is a large globular conjugated protein made up of four peptide chains with an iron-containing haem prosthetic group, which binds quite loosely to oxygen forming oxyhaemoglobin
Hb + 4O2 <---> Hb(O2)4
(pg 185)
60
Oxygen dissociation curve show
It shows the affinity for haemoglobin for oxygen
% saturation of haemoglobin with oxygen is on the y-axis, partial pressure of oxygen is on the X axis
(pg 186)
61
Describe the process of erythrocytes loading and unloading oxygen
Red blood cells enter the capillaries in the lungs where the action levels in the cells are very low, creating a steep concentration gradient, so oxygen moves into the RBCs
Arrangement of haemoglobin means that as soon as one, oxygen molecule binds to him group, multiple changes shape, making it easier for the next oxygen molecule to bind - Positive cooperativity
Because the oxygen is bound to the haemoglobin, the free oxygen concentration in the RBC stays low, so we diffusion gradient is maintained until all of the haemoglobin is saturated with oxygen
Blood reaches the body tissues, the situation was reversed.
Each oxygen molecule is released from the haemoglobin, it changes the shape and makes it easier to remove the remaining oxygen molecules
62
Explain the shape of the oxygen dissociation curve for human haemoglobin
At low, pO2, few haem groups are bound to oxygen, so haemoglobin does not carry much oxygen
At higher partial pressure of oxygen, more haem groups are bound to action, making it easier for more oxygen to be picked up
The haemoglobin becomes very saturated at high pO2, as all the haem groups become bound
(pg 186)
63
What is the Bohr effect and what impact does it have on the body
As a partial pressure of carbon dioxide rises, haemoglobin gives up oxygen more easily
This is important because in active tissues with a high partial pressure of carbon dioxide haemoglobin gives a production more readily
and in the Lungs, where proportion of carbon dioxide in the air is relatively low, oxygen binds to the haemoglobin molecules easily
(pg 187)
64
Why is it vital that a fetal haemoglobin has a higher affinity for oxygen than its mother's haemoglobin?
Oxygenated blood from the mother runs close to deoxygenated fetal blood in the placenta
If the blood of the fetus had the same affinity fraction as a blood, mother and little or no, oxygen will be transferred to the blood of the fetus
As fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin at each point along the dissociation curve it removes oxygen from the maternal blood as they move past each othe
65
What are the three ways carbon dioxide is transported around the body?
5% is carried and dissolved in the plasma
10-20% is combined with the amino groups in the polypeptide chains of haemoglobin to form a compound called Carbaminohaemoglobin
75 to 85% is converted into hydrogen carbonate ions (HCO3 -) in the cytoplasm of the red blood cells
66
Which enzyme catalyses the reaction between carbon dioxide and water in red blood cell cytoplasm and why is this vital to life?
Carbonic anhydrase
CO2 + H2O <--> H2CO3 <--> H+ + HCO3 -
H, plus ions and hydrogen carbonate ions provide a buffer for the blood
67
What is the chloride shift?
When negatively charged hydrogen carbonate ions move out of the erythrocytes in to the plasma by diffusion down a concentration gradient
Negatively charged chloride ions, then move into the Aretha sites, which maintains the electrical balance of the cell
68
What happens inside red blood cells when they reach the lungs
A low concentration of carbon dioxide is in the lungs, so carbonic anhydrase, catalyses the reverse reaction, breaking down, carbonic acid (H2CO3 -) into carbon dioxide and water
This means that hydrogen carbonate ions diffuse back into the Aretha sites and react with hydrogen ions to form or carbonic acid.
This intern releases free Cam dioxide which diffuses out of the cell into the lungs, which means that chloride ions diffuse out of the red blood cells back into the plasma down an electrical chemical gradient
69
How does haemoglobin help maintain pH?
CO2 + H2O <--> H2CO3 <--> HCO3 - + H+
HbO2 + H+ <--> HHb + O2
70
Explain how the structure of erythrocytes is adapted to their function in the body
Biconcave shape gives large surface area for gaseous exchange
and makes it possible to move through capillaries
erythrocytes contain oxygen carrying pigment haemoglobin
mature erythrocytes have no nucleus so more room for maximum amount of haemoglobin
contains enzyme carbonic anhydrase involved in carriage of carbon dioxide in blood
71
Which side of the heart does deoxygenated blood flow through
Right side
72
Which side of the heart does oxygenated blood flow through
The left side
73
What is the heart made of
Muscle contracts and relaxes in a regular rhythm without the need for rest, as it does not get fatigued
Surrounded by inelastic pericardial membranes, which prevent the heart from over distending with blood?
74
Describe the flow of blood around the circulatory system, focusing on the heart
Oxygenated blood enters the left atrium through the pulmonary veins
Its passage down the bicuspid valves into the left ventricle, where it is, then pushed through the semi lunar valves out of the heart by the aorta to oxygenate tissue
Once the blood has given up all its oxygen, it returns to the heart via the inferior and superior vena cava, entering the right atrium
Blood, then descends down past the tricuspid valve into the right ventricle where it is, then push to another set of semi lunar valves up into the main pulmonary artery, which then separates into the right and left pulmonary artery which goes towards the lungs to oxygenate
75
What is diastole
When the heart relaxes and the atria and ventricles fill, with blood,
the volume and pressure of the heart builds as the heart feels that the pressure of the arteries is at a minimum
76
What is systole
When the atria contract followed closely by the ventricle contraction
The pressure inside the increase is dramatically and blood is forced out of the right side of the heart to the lungs, and from the left side to the main body circulation
Low blood pressure in the heart, and at the end of the systole the blood pressure in the arteries is at a maximum
(pg 192)
77
What creates the sound of a heartbeat?
Blood pressure closing the heart valves 'lub-dub'
The sound comes as blood is forced against the atrioventricular valves as the ventricles contract, and the second sound comes as a backflow of blood close is the semilunar valves in aorta and pulmonary artery as ventricles relax
78
Why is cardiac muscle described as myogenic?
Own intrinsic rhythm, which prevents the body from wasting resources
79
Some factors that affect heart
Exercise, excitement, stress, et cetera
80
Describe how the basic rhythm of the heart is maintained
Maintained by a wave electrical excitation, rather like a nerve impulse
Wave of excitation begins in the pacemaker area called the Sino-atrial node, causing a treat to contract and so initiate in a heartbeat. A layer of nonconducting tissue prevents the excitation passing directly to the ventricles.
Electrical activity from the SAN is picked up by the atrioventricular node AVN, which imposes a slight delay for stimulating the bundle of His, a bundle of conductive tissue made up of Purkyne fibres which penetrate through the septum between the ventricles
The bundle of his split into two branches and conducts the wave excitation to the apex (bottom) of the heart
At the apex can the Purkyne fibres spread out through the walls of the ventricles and both sides. The spread of excitation triggers the contraction of the ventricles, starting the apex, which allows more efficient, emptying the ventricles.
81
How can scientist measure the spread of electrical citation through the heart
Electrocardiogram
82
What is tachycardia
Heartbeat is very rapid over 100 BPM
It's not a normal size or feet of a fever, frightened or angry. If it is abnormal. It may be caused by problems in the electrical control of the heart and may need to be treated by medication or by surgery.
(pg 194)
83
What is Bradycardia
Heart rate slows down to below 60 bpm
Have bradycardia because they are fit training the heart makes it beat more slowly and efficiently
Severe bradycardia can be serious and may need an artificial pacemaker to keep the heart beating steadily
(pg 194)
84
What is ectopic heartbeat
Extra heartbeats that are out of the normal rhythm
Most people have at least one a day. There are usually normal, but they can be linked to serious conditions when they are frequent
(pg 194)
85
What is atrial fibrillation?
Example of arrhythmia, which means an abnormal rhythm of the heart
Electrical impulses are generated in the atria, meaning they contract very fast up to 400 times a minute
They don't contract properly, and only some of the impulses are passed onto the ventricles which contract less often so the heart does not pump blood effectively
86
Explain why healthy, coronary arteries are important for maintaining a regular heart rhythm
Heart cardiac muscles needs good supply of oxygen and glucose to contract with a regular rhythm
coronary arteries supply blood carrying glucose and oxygen to heart
healthy coronary arteries provide good supply of blood to heart muscle so it can continue to beat
87
Explain the relationship between the Heart sounds and the events of the cardiac cycle
Pressure difference between atria and ventricles as atria empty and ventricles s start to contract means blood is forced against the atrio-ventricular valves which close to prevent backflow of blood into the atria
pressure difference between blood in artery and ventricles as they empty means blood hits semilunar valves which are closed to prevent backflow of blood into heart
88
Why is bradycardia common in diving mammals, such as whales and seals?
Bradycardia is the slowing of the heart
when animals dive they need to conserve their oxygen and food to last for whole dive
they undergo bradycardia as part of slowing down metabolism to enable them to stay under water as long as possible
89
Many people experience tachycardia when they travel to high altitudes. Explain why
Tachycardia is speeding up of the heart
at altitude there is less oxygen available in air – this means there is less oxygen available in blood
heart speeds up to compensate and
carry more oxygen to tissues, even if it isn’t
