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Biology GCSE > Blood and transport > Flashcards

Blood and transport Flashcards

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1
Q

Adaptations for gas exchange

A
  • Large surface area to allow faster diffusion of gases across the surface
  • Thin walls to ensure diffusion distances remain short
  • Good ventilation with air so that diffusion gradients can be maintained
  • Good blood supply (dense capillary network) to maintain a high concentration gradient so diffusion occurs faster
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2
Q

What process does gas exchange occur by?

A

diffusion

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3
Q

Why is breathing essential?

A
  • For maintaining high concentration gradients between the air in the alveoli and the gases dissolved in the blood
  • In particular, breathing keeps the oxygen level in the alveoli high and the carbon dioxide level low
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4
Q

How many alveoli does each lung contain?

A

around 250-300 million alveoli

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5
Q

What is the total surface area of each lung?

A

70 m^2

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6
Q

Ribs function

A

Bone structures that surround and protect the lungs, they also aid breathing (moving up and out or down and in)

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7
Q

Intercostal muscles function

A

Muscles between the ribs which control movement- causing inhalation and exhalation

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8
Q

Diaphragm function

A

A thin sheet of connective tissue and muscle at the bottom of the thorax that helps change the volume of the thorax to allow inhalation and exhalation.

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9
Q

Trachea

A

windpipe that connects the mouth and nose to the lungs, lined with goblet cells (to produce mucus) and ciliated epithelial cells (with cilia which move mucus up to the mouth).

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10
Q

Bronchus (plural- bronchi)

A

Large tubes branching off the trachea with one bronchus for each lung, also lined with goblet cells and ciliated epithelial cells.

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11
Q

Bronchioles function

A

The bronchi split to form smaller tubes called bronchioles in the lungs connected to alveoli.

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12
Q

Alveoli

A

Tiny, moist air sacs where gas exchange takes place, each alveolus is covered in capillaries.

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13
Q

Ventilation of the lungs

A

-Air passes through the following structures when we breathe in:
Trachea
Bronchus (plural: bronchi)
Bronchiole
Alveoli (the site of gas exchange where oxygen diffuses into the blood and carbon dioxide diffuses out)
-The diaphragm is a thin sheet of muscle that separates the chest cavity from the abdomen; it is ultimately responsible for controlling ventilation in the lungs
-When the diaphragm contracts it flattens and this increases the volume of the chest cavity (thorax), which causes a decrease in air pressure inside the lungs relative to outside the body, drawing air in
-When the diaphragm relaxes it moves upwards back into its domed shape and this decreases the volume of the chest cavity (thorax), which causes an increase in air pressure inside the lungs relative to outside the body, forcing air out
-The external and internal intercostal muscles work as antagonistic pairs (meaning they work in different directions to each other)
-During inhalation the external set of intercostal muscles contract to pull the ribs up and out:
-This also increases the volume of the chest cavity (thorax), decreasing air pressure, drawing air in
-During exhalation, the external set of intercostal muscles relax so the ribs drop down and in:
This decreases the volume of the chest cavity (thorax) increasing air pressure, forcing air out
-When we need to increase the rate of gas exchange (for example during strenuous activity) the internal intercostal muscles will also work to pull the ribs down and in to decrease the volume of the thorax more, forcing air out more forcefully and quickly – this is called forced exhalation
-There is actually a greater need to rid the body of increased levels of carbon dioxide produced during strenuous activity!
-This allows a greater volume of gases to be exchanged

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14
Q

Breathing in (C)/inspiration

A
  • external intercostal muscles contract
  • ribcage moves up and out
  • diaphragm contracts and flattens
  • volume of thorax increases
  • pressure inside thorax decreases
  • air is drawn in
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15
Q

Breathing out (R)/ exhalation

A
  • external intercostal muscles relax
  • ribcage moves down and in
  • diaphragm relaxes and becomes dome-shaped
  • volume of thorax decreases
  • pressure inside thorax increases
  • air is forced out
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16
Q

bronchioles

A

successve branch-like structures

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17
Q

Alveoli

A

The site of gas exchange

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18
Q

Alveolus

A
  • one alveoli
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19
Q

Alveoli adaptations

A
  • made of one layer of thin cells- short diffusion pathway: increases rate that carbon dioxide and oxygen can diffuse across
  • very large SA
  • Alveoli walls are moist- allows gases to dissolve (increases the rate of diffusion)
  • alveoli maintains concentration gradient
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20
Q

where is carbon dioxide in the blood?

A

Dissolved in the blood plasma

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21
Q

Double

A
  • carried deoxygenated blood from heart to lungs- gains oxygen flows back to heart
  • carries oxygenated blood to rest of body- gives up oxygen to rest of tissues- deoxygenated- flows back to heart- starting all over again
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22
Q

valves prevent

A

blood backflow

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23
Q

the cycle repeats around

A

70 times a minute

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24
Q

pacemaker cells

A

produce small electrical impulses which spread through the muscular walls of the heart, causing them to contract.

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25
Q

Artificial pacemaker

A

a small device placed under the skin above the heart- wire which carries an electrical current down to the heart- telling it to contract regularly like healthy, functioning pacemakers.

26
Q

The heart also needs its own supply of oxygenated blood

A

coronary arteries (branch off the aorta). These vessles circle the heart to make sure the muscle tissue gets all of the oxygen and nutrients that it needs.

27
Q

Arteries

A

carry blood away from the heart

28
Q

Capillaries

A

Exchange nutrients and oxygen with tissues

29
Q

veins

A

carry blood back to the heart

30
Q

The heart is part of a

A

double circulatory system

31
Q

What is the circulatory system?

A
  • It is a system of blood vessels with a pump (heart) and valves that maintain a one-way flow of blood around the body.
32
Q

How many chambers does the heart have?

A
  • It has four chambers separated into two halves.
33
Q

Right side of the heart

A

It pumps blood to the lungs for gas exchange (pulmonary circuit)

34
Q

Left side of the heart

A
  • It pumps blood under high pressure to the body (systemic circulation)
35
Q

Benefits of a double circulatory system

A
  • Blood travelling through the small capillaries in the lungs loses a lot of pressure which reduces the speed at which it can flow
  • By returning oxygenated blood to the heart from the lungs, the pressure can be raised before sending it to the body, meaning cells can be supplied with oxygenated blood more quickly
36
Q

The heart structure

A
  • The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs where oxygen diffuses in from the alveoli and carbon dioxide -diffuses out
  • The left side of the heart receives oxygenated blood from the lungs and pumps it to the body
37
Q

The chambers at the top of the heart are

A

atria

38
Q

The chambers at the bottom of the heart

A

ventricles

39
Q

Pathway of blood through the heart

A

-Deoxygenated blood enters the heart via the vena cava, emptying into the right atrium
-Blood flows down through a set of atrioventricular valves into the right ventricle
-When the ventricles contract, blood travels up through the pulmonary artery to the nearby lungs where gas exchange occurs (and the blood becomes oxygenated)
-Oxygenated blood returns to the heart via the pulmonary vein, emptying into the left atrium
Blood flows down through a set of atrioventricular valves into the left ventricle
-When the ventricles contract, blood travels up through the aorta, and to the rest of the body

40
Q

Adaptations of the heart

A

-The walls of the ventricles are much thicker than those of the atria as they are responsible for pumping blood out of the heart and so need to generate a higher pressure
-The wall of the left ventricle is much thicker than that of the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle is pumping blood at lower pressure to the lungs (which are close to the heart)
-There are two sets of valves inside the heart which function to prevent the backflow of blood in the heart:
-The atrioventricular valves separate the atria from the ventricles
-The semilunar valves are found in the two blood arteries that come out of the top of the heart
-They are unusual in that they are the only two arteries in the body that contain valves
These valves open when the ventricles contract so blood squeezes past them out of the heart, but then shut to avoid blood flowing back into the heart
The two sides of the heart are separated by the septum (with the portion separating the atria the atrial septum, the portion separating the ventricles the ventricular septum)
The septum is very important - it prevents the mixing of deoxygenated and oxygenated blood inside the heart
If blood were to mix, then less oxygenated blood would be pumped around the body
The heart is made of a special type of cardiac muscle tissue which does not fatigue like skeletal muscle
The coronary arteries supply the tissue of the heart with oxygenated blood - the heart needs a constant supply of oxygen (and glucose) for aerobic respiration to release energy to allow continued muscle contraction

41
Q

Which is the only artery in the body to carry deoxygenated blood?

A

The pulmonary artery

42
Q

Which is the only vein to carry oxygenated blood?

A

The pulmonary vein

43
Q

What is the natural resting heart rate controlled by?

A
  • a group of cells located in the right atrium

- These cells form a structure called the pacemaker

44
Q

What is the role of the pacemaker?

A

-It is to co-ordinate the contraction of the heart muscle, therefore it regulates the heart rate.

45
Q

Up to a point, the faster the heart contracts,

A

the more quickly oxygenated blood can be delivered around the body.

46
Q

A person at rest

A

the oxygen demand of their cells is relatively low and so a lower heart rate is maintained

47
Q

A person is excercising

A

the oxygen demand of their muscle cells increases and so a higher heart rate is necessary

48
Q

What does the pacemaker do?

A
  • The pacemaker sends out an electrical impulse which spreads to the surrounding muscle cells, causing them to contract
  • The pacemaker does this every time the heart needs to “beat”, so if a person has a resting heart rate of 60 beats per minute (bpm), then the SAN will be sending out electrical impulses on average once every second
49
Q

Sometimes the pacemaker of the heart stops functioning properly. What can this cause?

A

An irregular heartbeat

50
Q

What are artificial pacemakers?

A
  • They are electrical devices used to correct irregularities in the heart rate
  • The device is implanted just under the skin, with a wire that delivers an electrical current to the heart to help it contract regularly
51
Q

Blood flows through

A

the lumen of a blood vessel

52
Q

Artery structure

A
  • The wall is thicker than the walls of veins to withstand higher blood pressure
  • narrow lumen
  • A thick layer of smooth muscle and elastic fibres
  • Arteries must be able to withstand high pressures generated by the contracting heart, and maintain these pressures when the heart is relaxed
  • The wall of the artery is relatively thick with layers of collagen, smooth muscle and elastic fibres
  • The elastic fibres allow the artery wall to expand around blood surging through at high pressure when the heart contracts, these fibres then recoil when the heart relaxes – this alongside a narrow lumen maintains high blood pressure
53
Q

Veins structure

A
  • One way valves to prevent the backflow of blood
  • Thin layer of smooth muscle and elastic fibres
  • wider lumen compared to an artery
  • In contrast, veins receive blood that has passed through capillary networks; blood is at very low pressure and must be returned to the heart
  • The wall of the vein is relatively thin with thinner layers of collagen, smooth muscle and elastic fibres
  • The lumen of the vein is much larger than that of an artery
  • Veins contain valves that prevent the backflow of blood, helping return blood to the heart
54
Q

capillary structure

A
  • The wall of the capillary is made solely from a single layer of endothelial cells (this layer is also found lining the lumen in arteries and veins)
  • The wall is only one cell thick – this reduces the diffusion distance for oxygen and carbon dioxide between the blood and the tissues of the body
  • The cells of the wall have gaps called pores which allow blood plasma to leak out and form tissue fluid
55
Q

Function of blood

A
  • The role of blood in the body is to transport useful substances to every cell of the body, and to remove harmful waste substances
  • It also plays a vital role in transferring heat from “active” organs to cooler parts of the body (such as the extremities – hands and feet)
56
Q

What is blood?

A

It is a tissue consisting of the fluid plasma (which is largely water with dissolved substances in it)

57
Q

What is suspended in blood plasma?

A

Red blood cells, white blood cells and platelets are suspended in blood plasma

  • 55% plasma
  • 45% RBC, WBC,Platelets
58
Q

Red blood cells

A

-Red blood cells (RBCs) are cells with a distinctive biconcave disc shape
-This shape is a result of RBCs not having a nucleus
-The biconcave shape gives RBCs a large surface to volume ratio; this is a key adaptation to maximise the efficiency of diffusion of gases into and out of the cell
-The cytoplasm of an RBC is packed with the protein haemoglobin
-Oxygen binds reversibly with haemoglobin, forming the red pigment oxyhaemoglobin:
oxygen + haemoglobin ⇌ oxyhaemoglobin

59
Q

White blood cells

A

-White blood cells (WBCs) are part of the immune system, responsible for defending the body from infection by recognising and destroying pathogens
-WBCs defend the body in three particular ways:
-Phagocytes engulf and digest pathogens, destroying them
-Lymphocytes produce specific antibodies that help enhance phagocyte activity by sticking them together (clumping) or disabling pathogens
-Some lymphocytes produce a type of antibody called an antitoxin which is able to bind to toxic substances produced by pathogens, neutralising them
-WBCs have a variety of adaptations:
Phagocytes have a lobed nucleus and are autonomous - they leave the blood and patrol the tissues
Lymphocytes have a large nucleus and can produce antibodies extremely quickly

60
Q

Platelets

A
  • Platelets are fragments of cells (they contain cytoplasm but no nucleus)
  • When damage to a blood vessel occurs, the platelets are involved in forming a blood clot to prevent blood loss
  • Individuals with insufficient platelets cannot clot their blood effectively – this can be life-threatening if excessive damage occurs

Biology GCSE (15 decks)

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