transport animals Flashcards

1
Q

What is a transport system?

A

The system that transports required
substances around the body of an
organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why are specialised transport
systems needed in
multicellular animals?

A
• High metabolic demands (need 
lots of O2 and food & produce lots 
of waste products) so diffusion 
over long distances isn’t enough 
to supply the quantities needed
• SA:V ratio gets smaller as 
multicellular organisms get bigger, 
so the amount of surface area 
available to absorb or remove 
substances gets relatively smaller
• Molecules e.g. 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 
cell metabolism 
• Waste products of metabolism 
need to be removed from the cells 
and transported to excretory 
organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a circulatory system?

A
The transport system of an animal 
• Liquid transport medium that 
circulates around the system 
(blood)
• Vessels that carry the transport 
medium 
• Pumping mechanisms to move the 
fluid around the system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a mass transport

system?

A

A transport system where
substances are transported in a
mass of fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an open circulatory

system?

A
A circulatory system with a heart but 
few vessels to contain the transport 
medium. 
• Transport medium is pumped 
straight from the heart into the 
body cavity (haemocoel) , then it 
comes into direct contact with the 
tissues and the cells 
• This is where exchange takes 
place between the transport 
medium and the cells 
• Transport medium returns to the 
heart through an open-ended 
vessel
• Mainly found in invertebrate 
animals inc. insects and molluscs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the circulatory

system in insects

A
• Insect blood = haemolymph; it 
doesn’t carry O2 or CO2, it 
transports food and nitrogenous 
waste products & cells involved in 
defence against disease
• Body cavity is split by membrane 
and the heart extends along the 
length of the thorax and abdomen
• The haemolymph circulates, but 
steep diffusion gradient cannot be 
maintained for efficient diffusion
• Amount of haemolymph flowing 
through a particular tissue can’t be 
varied to meet changing demands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a closed circulatory

system?

A
A circulatory system where the 
blood is enclosed in blood vessels 
and does not come into direct 
contact with the cells of the body 
beyond the blood vessels 
• Amount of blood flowing to a 
particular tissue can be adjusted 
by widening or narrowing of blood 
vessels 
• Contain a blood pigment that 
carries the respiratory gases
• Found in many different animal 
phyla including: echinoderms, 
cephalopod molluscs, annelid 
worms and vertebrate groups 
(including mammals)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a single closed

circulatory system?

A
A circulatory system where the 
blood flows through the heart and is 
pumped out to travel all around the 
body before returning to the heart
• Blood passes through 2 sets of 
capillaries before it returns to the 
heart 
• 1st: Exchanges O2 and CO2
• 2nd: In the different organ 
systems, substances are 
exchanged between the blood and 
the cells 
• Due to passing though these 2 
sets of very narrow vessels, blood 
pressure in the system drops, and 
so the blood returns back to the 
heart slowly 
• Limits efficiency of the exchange 
processes, so the activity of 
animals tends to be relatively low
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Explain how fish can be so
active with a single closed
circulatory system

A
• Low metabolic demands on their 
bodies and efficient gaseous 
exchange 
• Body weight is supported by water 
they live in and they don’t maintain 
their own body temperature
• Countercurrent gaseous exchange 
mechanism in their gills that allows 
them to take lots of O2 from water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a double closed

circulatory system?

A
A circulatory system where the 
blood travels twice through the heart 
for each circulation of the body. 
Most efficient system for 
transporting substances around the 
body and involves 2 separate 
circulations
• 1st: Blood is pumped from the 
heart to the lungs to pick up O2 
and unload CO2, and then returns 
to the heart 
• 2nd: Blood flows through the heart 
and is pumped out to travel all 
around the body before returning 
to the heart again
Each circulate only passes through 
one capillary network, meaning that 
a high pressure and fast flow of 
blood can be maintained
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
Describe the following 
components found in some 
blood vessels: 
1. Elastic fibres 
2. Smooth muscle 
3. Collagen
A
1. Composed of elastin and can 
stretch and recoil, providing 
vessel walls with flexibility 
2. Contracts or relaxes, which 
changes the size of the lumen 
3. Provides structural support to 
maintain the shape and volume 
of the vessel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the roles of arteries

A
Carry blood away from the heart to 
the tissues of the body
• Carry oxygenated blood 
• EXCEPT in the pulmonary artery, 
which carries deoxygenated 
blood from the heart to the lungs, 
and the umbilical artery (during 
pregnancy) which carries 
deoxygenated blood form the 
foetus to the placenta 
• Blood in arteries is under higher 
pressure than blood in the veins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the structure of

arteries

A
Artery walls contain elastic fibres, 
smooth muscle and collagen. The 
outer layer of an artery (endothelium) 
is smooth so the blood flows easily 
over it
Wall consists of 3 layers:
• Inner layer (tunica intima) consists 
of a thin layer of elastic tissue 
which allows the wall to stretch 
(within limits maintained by 
collagen) to take the larger blood 
volume, and then recoil to help 
maintain blood pressure 
• Middle layer (tunica media) 
consists of a thick layer of smooth 
muscle 
• Outer layer (tunica adventitia) is a 
relatively thick layer of collagen 
and elastic tissue. This provides 
strength to withstand the high 
pressure, and recoil to maintain 
the pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to the elastic
fibres in between the
contractions of the heart?

A
The elastic fibres recoil ad return to 
their original length, helping to even 
out the surges of blood pumped 
from the heart to give a continuous 
flow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the structure of

arterioles

A
• Arterioles link the arteries and the 
capillaries 
• Have more smooth muscle and 
less elastin in their walls than 
arteries, as they have little pulse 
surge 
• Can constrict or dilate to control 
the flow of blood into individual 
organs 
• Vasoconstriction: when the 
smooth muscle in the arteriole 
contracts, it constricts the vessel 
and prevent blood flowing into a 
capillary bed
• Vasodilation: when the smooth 
muscle in the wall of an arteriole 
relaxes, blood flows into the 
capillary bed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are capillaries?

A
Microscopic blood vessels that link 
the arterioles with the venues, 
forming and extensive network 
through all the tissues of the body. 
They have very thin walls and allow 
the exchange of materials between 
the bloc and tissue fluid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are capillaries adapted for

their role?

A
• Provide a very large surface area 
for the dissuasion of substances 
into and out of the blood 
• Walls are 1 endothelial cell thick, 
giving a very thin layer for diffusion 
• Total cross sectional area of the 
capillaries is always greater than 
the arteriole supplying them so the 
rate of blood flow falls 
• Slow movement of blood through 
capillaries gives more time for 
exchange of materials by diffusion 
between the blood and the cells 
• Lumen is very narrow so red blood 
cells squeeze against the walls as 
they pass through, helping the 
transfer of O2 as it reduces 
diffusion path to the tissues. Also 
increases resistances and reduces 
rate fo flow 
• Walls are leaky allowing blood 
plasma and dissolved substances 
to leave the blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the roles of veins

A
• Carry blood away from the cells of 
the body towards the heart 
• They carry deoxygenated blood 
• EXCEPT pulmonary vein (carries 
oxygenated blood from the Lins to 
the heart), and umbilical vein 
(carries oxygenated blood from the 
placenta to the foetus)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the structure of veins

A
• Walls have lots of collagen, 
relatively little elastic fibre and the 
vessels have a wide lumen smooth 
endothelium to ease blood flow
• Thinner layers of collagen, smooth 
muscle and elastic tissue than in 
artery walls (because they don’t 
need to stretch and recoil and are 
not actively constricted in order to 
reduce blood flow)
• Contain valves to help the blood 
flow back to the heart and prevent 
it flowing in the opposite directions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is blood kept flowing in

the right direction in veins?

A
• As walls are thin, veins can be 
flattened by the action of 
surrounding skeletal muscle 
• Contraction of the surrounding 
skeletal muscle applies pressure 
to the blood, forcing the blood to 
move along in a direction 
determined by the valves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Do veins have a pulse?

A

No. The surges from the heart
pumping are lost as the blood
passes through the narrow
capillaries.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe venules

A
• They link the capillaries with the 
veins 
• They have very thin layers of 
muscle and elastic tissue outside 
the endothelium, and a thin outer 
layer of collagen 
• Several venules join to form a vein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the adaptations of
veins to overcome the problem
of transporting blood under
low pressure?

A
• Most veins have one way valves at 
intervals (flaps or inholdings of the 
inner lining of the vein) that only 
open when blood flows in the 
direction of the heart
• Many of the bigger veins run 
between the big active muscles in 
the body; when the muscles 
contract, they squeeze the veins, 
forcing blood towards the heart 
• Breathing movements of the chest 
act as a pump. The pressure 
changes and squeezing actions 
move blood in veins of the chest 
and abdomen towards the heart
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does blood consist of?

A
• Plasma (55%) - main component; 
yellow fluid containing many 
dissolved substances and carrying 
blood cells
• Red blood cells (erythrocytes)
• White blood cells (leucocytes)
• Platelets - fragments of large cells 
called megakaryocytes, and they 
are involved in the clotting 
mechanism of the blood 
• Dissolved glucose, amino acids, 
mineral ions, hormones 
• Large plasma proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Describe 3 plasma proteins
``` • Albumin - important for maintain the osmotic potential in the blood • Fibrinogen - important in blood clotting • Globulins - involved in transport and the immune system ```
26
What are the functions of the | blood?
``` Maintenance of a steady body temperature • Acts as a buffer, minimising pH changes Transport of: • O2 to, and CO2 from, the respiring cells • Digested food from the small intestine • Nitrogenous waste products from the cells to the excretory organs • Hormones • Food molecules from storage compounds to the cells that need them • Platelets to damaged areas • Cells and antibodies involved in the immune response ```
27
What is oncotic pressure?
``` The tendency of water to move into the blood in the capillaries from the surrounding fluid by osmosis as a result of the plasma proteins (which gibe the blood in the capillaries a low water potential) • - 3.3 kPa ```
28
What is hydrostatic pressure?
``` The pressure created by water in an enclosed system. As blood flows through the arterioles into the capillaries, it is still under pressure every time the heart contacts. This is hydrostatic pressure • 4.6 kPa at arterial end • 2.3 kPa at venous end ```
29
What is tissue fluid?
``` The solution surrounding the cells of multicellular animals. Similar to blood plasma, but doesn’t contain most of the cells found in blood, nor does it contain plasma proteins Diffusion takes places between the blood and the cells through the tissue fluid ```
30
Describe the formation of | tissue fluid
``` • At the arterial end, hydrostatic pressure is higher than oncotic pressure attracting water in by osmosis, so fluid is squeezed out of the capillaries • This fluid fills the spaces between the cells and is called tissue fluid ```
31
What happens as blood moves through the capillaries towards the venous system?
``` The balance of forces changes • Hydrostatic pressure falls to 2.3kPa in the vessels, as fluid has moved out and the pulse is lost • Oncotic pressure is now stronger than hydrostatic pressure, so water moves back into the capillaries by osmosis • By the time blood returns to veins, 90% of the tissue fluid is back in the blood vessels ```
32
What is lymph?
``` Modified tissue fluid that is collected in the lymph system • 10% of the liquid that leaves the blood vessels drains into lymph capillaries • Similar in composition to plasma and tissue fluid, but has less O2 and fewer nutrients • Contains fatty acids absorbed from villi in the small intestine ```
33
How is fluid in lymph vessels | transported?
``` • Through the squeezing of body muscles • One-way valves (like in veins) prevent back flow • Eventually lymph returns to the blood, flowing into the right and left subclavian veins ```
34
Describe the lymph nodes
``` • Found along the lymph vessels • Lymphocytes build up here when necessary and produce antibodies which are then passed into the blood • Also intercept bacteria and debris from the lymph, which are ingested by phagocytes found in the nodes • Major sites: neck, armpits, stomach, groin ```
35
What are enlarged lymph | nodes a sign of?
That the body is fighting off an | invading pathogen
36
``` Describe haemoglobin (in terms of transporting oxygen) ```
``` Very larger globular conjugated protein made up of 4 peptide chain, each with a Fe2+ containing haem group which is said to have a high affinity for oxygen • The Fe2+ ion can attract and hold a single O2 molecule • 300 million haemoglobin molecules in each red blood cell, and each can bind to 4 O2 molecules ```
37
What is the reaction for oxygen | binding with haemoglobin?
Hb + 4O2 ⇌ Hb(O2)4 | haemoglobin + oxygen ⇌ oxyhaemoglobin
38
Describe how oxygen is | carried by erythrocytes
``` 1. In the lungs, O2 moves into the erythrocytes and binds with the haemoglobin 2. Arrangement of haemoglobin molecule means that as soon as one O2 molecule binds to a haem group, the molecule changes shape, making it easier for the next O2 molecules to bind (known as positive cooperativity) 3. O2 is bound to the haemoglobin so, free O2 concentration in the erythrocyte stays low and steep diffusion gradient is maintained until all of the haemoglobin is saturated with O2 4. When blood reaches body tissues, O2 moves out of the erythrocytes down a concentration gradient 5. Once the first O2 molecule is released by the haemoglobin, the molecule changes shape, and it becomes easier to remove the remaining O2 molecules ```
39
What is an oxygen dissociation | curve?
``` Graph showing the relationship between oxygen and haemoglobin at different partial pressures of oxygen (pO2) • They show the affinity of haemoglobin for oxygen ```
40
Describe the oxygen | dissociation curve graph
``` • A very small change in the pO2 in the surrounds makes a significant difference to the saturation of the haemoglobin with O2 because once the first O2 is added, change in shape of molecule means other O2 are added rapidly • Curve levels out at highest pO2s because all the haem groups are bound to O2 so the haemoglobin is saturated ```
41
What is the effect of partial pressure on the movement of oxygen in the body?
``` • High pO2 in the lungs means that the haemoglobin in erythrocytes is rapidly loaded with O2 • Relatively small drop in respiring tissues means O2 is released rapidly from the haemoglobin to diffuse into the cells • This effect is enhanced by relatively low pH in tissues compared with the lungs ```
42
How much of the O2 carried in erythrocytes is released into the body cells when you’re not very active?
• Only 25% • The rest acts as a reservoir for when the demands of the body increase suddenly
43
What is the effect of carbon | dioxide?
``` At high partial pressures of CO2, haemoglobin gives up oxygen more easily. This is known as the Bohr effect • Bohr shift on oxygen dissociation curve = shift to the right Important in the body because as a result: • In active tissues with high pCO2, haemoglobin gives up its O2 more readily • In the lungs where the proportion of CO2 in the air is relatively low, O2 bids to the haemoglobin molecules easily ```
44
What is the difference between fetal and adult haemoglobin and why?
``` Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin at each point along the dissociation curve • Foetus completely depends on its mother to supply it with oxygen • Mother’s oxygenated blood runs close to the deoxygenated fetal blood in the placenta • If fetal blood had the same affinity for O2 as the blood of the mother, the little or no O2 would be transferred to the blood of the foetus • Fetal haemoglobin has a higher affinity for O2, so it removes O2 from the maternal blood as they move past each other • Fetal haemoglobin on oxygen dislocation curve = shift to the left ```
45
What are the 3 ways in which | carbon dioxide is transported?
``` • 5% is dissolved in the plasma • 10-20% is combined with the main groups in polypeptide chain of haemoglobin to form a compound called carbaminohaemoglobin • 75-85% is converted into hydrogencarbonate ions (HCO3-) in the cytoplasm of red blood cells ```
46
What happens when CO2 | diffuses into red blood cells?
``` It combines with water to form a weak acid called carbonic acid. This reaction is catalysed the enzyme carbonic anhydrase CO2 + H2O ⇌ H2CO3 The carbonic acid then dissociates to release H+ and HCO3- ions H2CO3 ⇌ HCO3- + H+ ```
47
What happens to the HCO3- | and H+ ions next?
``` Hydrogencarbonate ions (HCO3-) • Diffuse out of the red blood cell into the plasma • Chloride shift - charge in the red blood cell is maintained by the movement of chloride ions (Cl-) from the plasma into the red blood cell Hydrogen ions (H+) • Build of of these could cause the contents of the red blood cell to become very acidic • Taken out of solution by associating with haemoglobin to produce haemoglobinic acid (HHb) • The haemoglobin is acting as a buffer (a compound that maintains a constant pH) ```
48
What is the benefit of converting the carbon dioxide into hydrogencarbonate ions?
Carbon dioxide must be removed from the body or it makes the blood dangerously acidic .Since carbon dioxide is quickly converted into bicarbonate ions, this reaction allows for the continued uptake of carbon dioxide into the blood down its concentration gradient
49
What happens when the blood | reaches the lung tissue?
``` • Relatively low concentration of carbon dioxide • Carbonic anhydrase catalyses the reverse reaction, breaking down carbonic acid into CO2 and water • HCO3- ions diffuse back into the erythrocytes and react with H+ ions to form more carbonic acid • When this is broken down by carbonic anhydrase it releases free CO2, which diffuses out of the blood into the lungs • Cl- ions diffuse out of the erythrocytes back into the plasma down an electrochemical gradient ```
50
Describe the Bohr effect
``` Effect an increasing concentration of CO2 has on haemoglobin • CO2 enters erythrocytes forming carbonic acid, which dissociates to release H+ ions • H+ ions make pH of cytoplasm more acidic • Acidity alters tertiary structure of haemoglobin and reduces the affinity of it for O2 • Haemoglobin is unable to hold as much O2, and O2 is released from the oxyhemoglobin to the tissues • Respiring tissues = more CO2, so more O2 will be released ```
51
Why is the Bohr effect | important?
``` It results in more O2 being released where more CO2 is produced in respiration, which is what muscle need for aerobic respiration to continue ```
52
Describe the flow of blood | through the right side of the heart
``` Deoxygenated blood 1. Enters the right atrium from the superior and inferior vena cave at relatively low pressure 2. As blood flows in, slight pressure builds up until the AV valve opens to let blood pass into the right ventricle 3. When both the atrium and ventricle are filled with blood, the atrium contracts, forcing all the blood into the right ventricle and stretching the ventricle walls 4. As right ventricle starts to contract, AV valve closes, preventing back-flow of blood 5. Tendinous cords make sure that the valves are not turned inside out by the pressures exerted when the ventricle contracts 6. Right ventricle contracts fully and pumps oxygenated blood through the semilunar valves into the pulmonary artery, which transports it to the capillary beds of the lungs. Semilunar valves prevent back-flow of blood into the heart. ```
53
Describe the flow of blood | through the left side of the heart
``` Oxygenated blood 1. Enters the left atrium from the pulmonary vein 2. As pressure in the atrium builds, the AV valve opens, so the ventricle also fills with blood 3. When both the atrium and ventricle are full, the atrium contracts, forcing all the blood into the left ventricle 4. The left ventricle then contracts and pumps oxygenated blood through semilunar valves into the aorta and around the body 5. As the ventricle contracts, the AV valve closes, preventing any back flow of blood ```
54
``` How are the following chambers adapted for the blood pressure they handle? 1. Atria 2. Right ventricle 3. Left ventricle ```
``` Atria • Muscle of atrial walls is very thin • These chambers do not need to create much pressure • Function is to receive blood from veins and push it into ventricles Right Ventricle • Thicker walls than atria • Needed to pump blood out heart • Pumps deoxygenated blood to the lungs, which are beside the heart, so blood doesn’t travel very far • Alveoli in the lungs are very delicate and could be damaged by very high blood pressure Left Ventricle • Walls 2 or 3 times thicker than RV • Blood from LV pumped out aorta so needs enough pressure to overcome the resistance of systemic circulation ```
55
What is the cardiac cycle?
The events of a single heartbeat (which lasts about 0.8 seconds in a human adult), composed of diastole and systole
56
What happens in diastole?
``` • The heart relaxes • The atria and then the ventricles fill with blood • Volume and pressure of blood in the heart builds as the heart fills, but the pressure in the arteries is at a minimum ```
57
What happens in systole?
``` • The atria contract (atrial systole) followed by the ventricles (ventricular systole) • Pressure inside the heart increases 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 • Volume and pressure of the blood in the heart are low at the end of systole • Blood pressure in the arteries is at a maximum ```
58
Describe pressure changes | during the cardiac cycle
``` Aortic pressure (brown) • Rises when ventricles contract as blood is forced into the aorta • Then gradually falls but never below 12 kPa, as the elasticity of its wall creates a recoil action • Recoil produces a temporary rise in pressure at the start of the relaxation phase Atrial pressure (pink) • Always relatively low because thin walls of the atrium can’t create much force • Highest when they are contracting, but drops when the left AV valve closes and its walls relax • Atria then fill with blood leading to a gradual build-up of pressure • Slight drop when left AV valve closes and some blood moves into the ventricle Ventricular pressure (yellow) • Low at first, but gradually increases as the ventricles fill with blood as the atria contract • Left AV valves close and pressure rises dramatically as thick walls of ventricle contract • As pressure rises above aortic pressure, blood is forced into the aorta past the semilunar valves • Pressure falls as the ventricles empty and the walls relax Ventricular volume (green) • Rises as atria contract and ventricles fill with blood, then drops suddenly as blood is forced out into the aorta when the semilunar valve opens • Volume increases again as the ventricles fill with blood ```
59
Describe the sounds of the | heartbeat
``` • Made by blood pressure closing the heart valves • Two sounds of a heartbeat are described as “lub-dub” • 1st sound is when blood is forced against the AV valves as ventricles contract • 2nd sound is when a back flow of blood closes the semilunar valves in the aorta and pulmonary artery as the ventricles relax ```
60
Why is cardiac muscle said to | be ‘myogenic’?
``` It has its own intrinsic rhythm at around 60 bpm. • Prevents the body wasting resources to maintain basic heart rate • Average resting heart rate of an adult is 70 bpm because other factors also affect heart rate (e.g. exercise, excitement and stress) • Basic rhythm of the heart is maintained by a wave of electrical excitation ```
61
How is the basic rhythm of the | heart maintained?
``` 1. A wave of electrical excitation begins in the pacemaker area called the SAN, causing atria to contract and so initiating the heartbeat. Layer of nonconducting tissue prevents excitation passing directly to the ventricles 2. Electrical activity form the SAN is picked up the the AVN, which imposes a slight delay before stimulating the bundle of His ( a bundle of conducting tissue made up of Purkyne fibres) which penetrate through the septum between the ventricles 3. bundle of His splits into 2 branches and conducts the wave of exception to the apex of the heart 4. At the apex, the Purkyne fibres spread out through the walls of the ventricles on both sides, Spread of excitation triggers contracting of ventricles, starting at apex. Starting here allows more efficient emptying of the ventricles ```
62
What is the importance of the delay is the spread of the excitation from the SAN to the AVN?
Ensures that the atria have stopped contracting before the ventricles start
63
What is an electrocardiogram | (ECG)?
``` A technique for measuring tiny changes in the electrical conductivity of the skin that result from the electrical activity of the heart. This produces a trace that can be used to analyse the health of the heart ```
64
What is tachycardia?
``` • Heartbeat is very rapid; >100 bpm • Normal during exercise, fever, fear or anger • If abnormal, may be caused by problems in electrical control of heart • Treated by medication or surgery ```
65
What is bradycardia?
``` • Heart rate slows down < 60 bpm • Common in people who are fit - training makes heart beat more slowly and efficiently • Severe bradycardia can be serious and may need an artificial pacemaker ```
66
What is ectopic heartbeat?
``` • Extra heartbeats that are out of normal rhythm • Most people have at least 1 a day • Usually normal but can be linked to serious conditions when they are frequent ```
67
What is atrial fibrillation (example of | arrythmia)?
``` • Abnormal rhythm of the heart • Rapid electrical impulses generated in atria so they contract very fast and not properly • Only some of impulses passed to ventricles, which therefore contract less often, so heart doesn’t pump blood effectively ```