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Module 3 > Transport in animals > Flashcards

Transport in animals Flashcards

1
Q

Why do small animals not need a transport system and large animals do

A

-Cells are close to the environment to which they live
-Diffusion will supply enough O2 and nutrients to supply the cell
-Larger organisms will have two layers of cells
-Diffusion distance too long
- Diffusion alone will be to slow to supply all the requirements

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2
Q

What factors influence the need for a transport system

A

-size
-SA:V
- Level of metabolic activity

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3
Q

How does size affect the need for a transport system

A
  • cells inside larger organism is further from the surface
    -diffusion pathway is increased
    -Diffusion rate is reduced and too slow to supply all the requirements
  • Outer layers of cells use up supplies so less will reach the cells inside the body
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4
Q

How does SA:V affect the need for a transport system

A
  • smaller animals have a large SA:V so have sufficient area of body surface in which exchange can occur
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5
Q

How does metabolic activity affect the need for a transport system

A
  • animals need energy for food so can move around
  • releasing energy from food by aerobic respiration requires O2
  • If animals active cell needs good supplies of O2 and nutrients to supply energy for movement
  • animals also need more energy for insulation
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6
Q

Features of a good transport system

A
  • a fluid/medium to transport O2 and wastes (Blood)
  • pump to create pressure that will push fluid around the body (Heart)
  • Exchange surfaces that enables substances to enter/leave the blood (capillaries)
    -tube/vessels to carry blood by mass flow
    -two circuits - one to pick up O2 and another to deliver O2 to tissues
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7
Q

What is a single circulatory system

A

Fish
Blood flows through the heart once
Heart - Gills - Body - Heart

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8
Q

What is a double circulatory system

A

Mammals
- two separate circuits, blood flows through the heart twice
Pulmonary circulation: blood to lungs to pick up O2
Systemic circulation: 02 and nutrients to tissues
Heart- Body - Heart - Lungs - Heart

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9
Q

Disadvantages of a single circulatory system

A
  • blood pressure drops as blood passes through the tiny capillaries of the gills
  • Blood has LP as flows around body and won’t flow very quickly
  • rate of O2 deliverance and CO2 removal limited
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10
Q

Why do fish have a single circulatory system

A

-not as metabolically active as don’t need to maintain their body temperature
-Need less energy
- SCS supplies enough O2 and nutrients to meet requirements

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11
Q

Why does the pressure change in DCS

A
  • blood pressure isn’t high in pulmonary circulation otherwise damages the delicate capillaries in the lungs
    -Heart increases pressure as it has passed through the lungs, so blood is under higher pressure and flows through body quickly
  • systemic circulation carries at higher pressure then pulmonary circulation
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12
Q

What is an open circulatory system

A

Blood is not held in vessels
-blood circulates through body cavity, tissues and cells bathed directly in blood

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13
Q

How does an insects circulatory system work

A

OCS
-muscular pumping organ like the heart that lies just underneath the dorsal (upper) surface of the body
- Blood from body enters heart through pores called ostia
-heart then pumps blood towards head by peristalsis
- at forward end of the heart (nearest the head) blood simply pours out into the body cavity

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14
Q

What happens in the CS of more active insects

A

-open ended tubes attached to the heart
-direct blood towards active parts of the body

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15
Q

Disadvantages of OCS

A
  • blood pressure low
  • Blood flow slow
  • circulation of blood affected by body movements/ lack (some have to be constantly active to help circulate the blood
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16
Q

What is a closed circulatory system

A

One in which blood is held within vessels

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17
Q

Advantages of a closed circulatory systems

A

-high pressure so blood flows more quickly
-rapid delivery of O2 and nutrients
- rapid removal of CO2 and other wastes
- transport independent of body movements

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18
Q

Features of arteries

A

-Carries blood away from the heart
- blood at high pressure so artery wall must be thick in order to withstand pressure
-lumen small to maintain HP
- Inner wall folded to allow lumen to expand as blood flow increases

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19
Q

3 layers of arteries

A
  • inner layer (tunica intima) - thin layer of elastic tissue which allows wall to stretch and recoil to help maintain BP
    -Middle layer (tunica media) - thick layer of smooth muscle
  • Outer layer (tunica adventitia) thick layer of collagen and elastic tissue - provides strength to withstand HP and recoil to maintain pressure
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20
Q

Features of arterioles and why the smooth muscle in it is so important

A

-small blood vessels that distribute blood from artery to capillaries
-Consist of a layer of smooth muscle
-Contraction of muscle constricts diameter of arteriole
- increases resistance to flow and reduced rate of blood flow
- Constriction of arteriole walls used to divert flow of blood to regions of the body demanding more O2

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21
Q

Features of capillaries

A

Have thin walls to allow exchange of materials between blood and tissue fluid
- narrow lumen same as RBC, RBC squeezed against walls helping transfer O2 as reduces diffusion distance, increases resistance and reduces rate of flow
- walls consist of a single layer of flattened endothelial cells - reduces diffusion distance
- Walls are leaky - allow blood plasma and other dissolved substances to leave the blood

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22
Q

Features of venules

A

Small blood vessels that collect blood from capillaries and leads them into the veins
- Consists of thin layers of muscle and elastic tissue outside the endothelium, and thin outer layer of collagen

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23
Q

Features of veins

A

carry blood back to the heart, BP is low so walls don’t need to be thick
- lumen large to ease flow of blood
- walls have thinner layers of collagen and smooth muscle and elastic tissue then arteries
- contain valves to prevent back flow
- walls are thin so contraction of surrounding skeletal muscle applies pressure to blood forcing blood to move in direction determined by valves

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24
Q

What does plasma consist of

A

Fluid portion of the blood
contains many dissolved substances i.e. O2, CO2, minerals, glucose, amino acids, hormones, plasma proteins
Cells i.e. RBC, WBC, platelets, lymphocytes
Plasma proteins

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25
Q

What is tissue fluid

A

fluid surrounding cells and tissues
- similar to blood plasma but does not contain most of the cells in blood/ plasma proteins

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26
Q

How is tissue fluid formed

A

By plasma leaking from capillaries
- surrounds cells in tissue and supplies them with O2 and nutrients
- happens because as plasma leaks it carries all the dissolved substances into the tissue fluid
- mass flow rather than diffusion
- waste products from cell metabolism carried back into capillary as some of the tissue fluid returns to the capillary
- some neutrophils/ few proteins/ few fats

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27
Q

Why does the formation of tissue fluid happen

A
  • artery reaches tissues branches into arterioles into capillaries
  • at arterial end of capillary blood is at high hydrostatic pressure which pushes blood fluid out of holes in capillary wall
  • fluid that leaves consists of plasma with dissolved nutrients and O2, cells and plasma proteins are too large to leave
  • tissue fluid surrounds so exchange of gases and nutrients can occur across plasma membranes
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28
Q

How does the tissue fluid return back to the blood

A

blood pressure at the venous end of the capillary is much lower
- carries CO2 and other waste products such as urea back into the blood

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29
Q

What happens to the tissue fluid that doesn’t return back into the blood

A
  • some tissue fluid is directed into another tubular system called the lymphatic system
  • drains excess tissue fluid out of the tissues and returns it to the blood system in the subclavian vein in the chest
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30
Q

What does the lymphatic system consist of

A
  • similar in composition to tissue fluid
  • contains more lymphocytes as these are produced by lymph nodes
  • few proteins/ more fats
  • lymph nodes play important role in immune response
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31
Q

Hydrostatic/ Oncotic pressure of blood plasma

A

high/ slightly negative

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32
Q

Hydrostatic/ Oncotic pressure of tissue fluid

A

low/ less negative

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33
Q

Hydrostatic/ Oncotic pressure of lymph

A

low/ less negative

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34
Q

What is hydrostatic pressure

A

pressure fluid exerts when pushing against the sides of a blood vessel

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35
Q

What is oncotic pressure

A

pressure created by the osmotic effects of the solutes
- if has negative figure tends to pull water back into the blood

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36
Q

How do you work out which way the fluid is moving

A
  • work out difference in hydrostatic pressure
    -work out difference in oncotic pressure
  • add them together, if number is negative then moves back into the capillary
37
Q

What kind of muscle is the heart

A

The cardiac muscle

38
Q

Where are the ventricles and atria in the heart

A
  • two main pumping chambers - ventricles
  • two thin walled chambers above ventricles - atria
39
Q

External features of the heart

A

Lying over the surface are coronary arteries that supply oxygenated blood to the heart
- if become constricted can have severe consequences
- restricted blood flow reduced delivery of O2 and nutrients
- may cause angia/ heart attack

40
Q

How does the blood enter the heart

A
  • deoxygenated blood flows through vena cava into the right atrium
  • oxygenated blood flows from pulmonary vein into left atrium
41
Q

What happens after blood enters the atria

A
  • blood flows through the atrioventricular valves into the ventricles
42
Q

What are attached to the valves

A

tendinous cords to prevent the ventricles turning inside out when the ventricle walls contract

43
Q

What separates the ventricles from each other

A

the septum
- ensure oxygenated/ deoxygenated blood stay separate

44
Q

What happens after the blood enters the ventricles

A

deoxygenated blood flows into pulmonary artery
oxygenated blood flows into aorta - carries blood to arteries

45
Q

What are the semi- lunar valves

A

at the base of the major arteries
- prevent blood flowing back to the heart as the ventricles relax

46
Q

Features of the atria

A
  • muscle of atria walls is very thin as don’t need to create that much pressure
  • function is to receive blood from the veins and push it into the ventricles
47
Q

Features of the right ventricle

A
  • thicker then walls of atria enabling it to pump blood out of the heart
  • pumps deoxygenated blood to the lungs
  • not very high pressure as could damage alveoli and lungs are just behind so does not need to travel very far
48
Q

Features of the left ventricle

A
  • 2x/ 3x thicker then right ventricle
  • blood pumped out of aorta and need sufficient pressure to overcome the resistance of systematic circulation
49
Q

Features of cardiac muscle

A

consists of fibres that branch producing cross bridges
- helps spread the stimulus around the heart and ensures muscle can produce a squeezing rather then a simple reduction in length
- lots of mitochondria between muscle fibrils to supply energy for contraction
- muscle separated by intercalated discs which facilitate synchronised contraction
- each cell has a nucleus and divided into contractile units called sarcomeres

50
Q

What is the cardiac cycle

A

the sequence of events in one full heartbeat

51
Q

Explain cardiac cycle sequence

A

1) Diastole - muscular walls of 4 chambers relax, elastic recoil causes chambers to increase in volume allowing blood to flow in from the vein
2) Atrial Systole - right and left atria contract, thin wall makes only small amount of pressure pushing blood into ventricles
3) Ventricular systole - right and left ventricles pump - contraction at base (apex) so blood is pushed upwards towards the arteries

52
Q

Main purpose of the valves

A

Blood flow is in correct direction
-opened/closed by changed in blood pressure in various chambers in the heart

53
Q

How do the atrioventricular valves work after systole

A

ventricular walls relax and recoil
-pressure in ventricles rapidly drops below pressure in the atria
-blood in the atria push the atrio-ventricular valves open
- blood entering heart flows straight through atria and into ventricles
-pressure in atria and ventricles rise slowly as they fill with blood
-valves remain open while atria contract but close when atria relax
-as ventricles contract (systole) pressure of blood in the ventricles rises
-when pressure rises above that in the atria the blood starts to move upwards
-this prevents blood flowing back to atria

54
Q

When are the semi - lunar valves closed

A

-before ventricular contraction, the pressure in the major arteries is higher then ventricles
- this means the semi - lunar valves are closed

55
Q

When are the semi-lunar valves open

A

Ventricular systole raises blood pressure in the ventricles quickly
- once pressure in ventricles is above pressure in arteries the semi-lunar valves are pushed open
-blood under high pressure so forced out in one powerful spurt
-once ventricles walls have finished contracting, the heart muscles start to relax (diastole)

56
Q

What happens to the semi-lunar valves after diastole

A
  • elastic tissues in the walls of the ventricles recoils
    -This stretches the muscle out again and the ventricle returns to its original size
    -This causes pressure in the ventricles to drop quickly
  • As it drops below the pressure in the major arteries, the blood starts to flow back towards the ventricles
  • Semi lunar valves are pushed closed by blood collecting in the pockets of the valves
    -this prevents blood returning to ventricles
57
Q

What is our pulse

A

Wave created when semi lunar valves close

58
Q

Why is their elastic tissue in the heart

A
  • artery walls stretch when blood leaves the heart
  • when blood leaves the heart these walls stretch
    -elastic recoil helps maintain pressure in aorta as pressure drops when blood moves out
  • further blood flows along arteries the more the pressure drops and fluctuations become less obvious
59
Q

Why is important to maintain the pressure gradient between the aorta and arterioles

A

to keep blood flowing towards the tissues

60
Q

What does myogenic mean

A

muscle can initiate its own contraction
- muscle will contract relax rhythmically even if not connected to the body

61
Q

What is fibrillation

A

When the contractions of the heart chambers aren’t synchronised

62
Q

What is the SAN (sino-atrial node)

A

at top of right atrium, near the point where vena cava empties blood
- small patch of tissue that sends out waves of electrical excitation at regular intervals in order to initiate contractions
- also known as the pacemaker

63
Q

How do the atria contract

A
  • wave of excitation spreads over both walls of the atria
  • travels along membranes of muscle tissue
  • as wave of excitation passes it causes the cardiac muscle to contract
  • this is an arterial systol
64
Q

What is the atrio- ventricular node (AVN)

A

tissue at base of atria unable to conduct wave of excitation so cannot spread down ventricle walls
- at top of interventricular septum is AVN
- only route that can initiate wave of excitation through to the ventricles

65
Q

Why is the wave of AVN excitation delayed

A

allows time for atria to finish contracting and for blood to flow down into ventricles before they begin to contract

66
Q

How do the ventricles contract

A

-after delay wave of excitation carried away from AVN and down specialised tissue called purkyne tissue
- this runs down interventricular septum
- at base of septum wave of excitation spreads out over walls of ventricles
- as excitation spreads up from the base (apex) of the ventricles it causes it to contract
- this means ventricles contract from base upwards
-this pushes blood up towards major arteries of the heart

67
Q

What is purkyne tissue

A

consists of specially adapted muscle fibres that conduct wave of excitation from AVN down to septum of the ventricles

68
Q

How do you monitor the activity of a heart

A

Using an electrocardiogram
- involves attaching a number of sensors to the skin
- electrical activity generated by the heart spreads through tissues next to the heart and outwards towards the skin
- sensors on the skin pick up electrical excitation created by the heart and convert it into a trace

69
Q

What do the different letters of the waves show

A

P wave - excitation of atria
QRS wave - excitation of the ventricles
T wave - diastole

70
Q

Different types of heartbeats

A

Sinus rhythm - normal
Bradycardia - slow
Tachycardia - fast
Atrial fibrillation - atria beating more frequently then ventricles
Ectopic Heart beat - third beat is an early ventricular beat

71
Q

What does haemoglobin become when it picks up oxygen

A

oxyhaemoglobin

72
Q

Features of haemoglobins haem group

A
  • each polypeptide chain contains single iron ion
  • iron ion can attract and hold an oxygen molecule - high affinity for O2
73
Q

How is O2 transported around the body

A

O2 becomes associated with haemoglobin at alveoli and bind reversibly
- takes O2 out of solution and maintains a steep conc gradient allowing more O2 to enter the blood and diffuse into cells
- blood carries O2 from lungs to heart before round body to supply tissues
- O2 then dissociated from haemoglobin at tissues as cells need O2 for respiration

74
Q

What is meant by partial pressure of O2

A

concentration of O2 measured by the relative pressure that it contributes to a mixture of gases
- measured by KPa

75
Q

What is the S shaped curve called to describe Percentage saturation with oxygen vs partial pressure of O2

A

haemoglobin dissociation curve

76
Q

What happens at low oxygen tension

A

haemoglobin does not readily associate with O2 molecules
- haem groups that attract O2 are at the centre of the haemoglobin molecule
- difficult for O2 to reach the haem group and associate
- difficulty in combining with first O2 molecule accounts for low saturation level of haemoglobin at low O2 tensions

77
Q

What happens as O2 tension rises

A

diffusion in haemoglobin molecule increases
- after one group attaches causes conformational change changing haemoglobins shape so O2 can associate with haem groups more easily

78
Q

What happens as the haemoglobin reaches 100% saturation level

A

Curve levels off

79
Q

How is fetal haemoglobin different

A

has a higher affinity for 02 then adult haemoglobin so to the left of the curve
- because fetal haemoglobin must be able to associate with O2 in an environment where oxygen tension is low enough for adult haemoglobin to release O2

80
Q

Why is the oxygen tension low in the placenta

A

fetal haemoglobin absorbs O2 from surrounding fluid
- this causes O2 from mothers blood fluid into the placenta
- reduces O2 tension in mothers blood, which in turn makes maternal haemoglobin dissociate with more 02

81
Q

What does affinity mean

A

a strong attraction

82
Q

How is CO2 transported

A

5% directly in the plasma
10% combined directly with haemoglobin to form carbaminohaemoglobin
85% transported in the form of hydrogencarbonate ions

83
Q

How are hydrogencabonate ions formed

A

-CO2 diffuses into blood plasma of RBC where it forms a weak acid called carbonic acid catalysed by carbonic anhydrase
-carbonic acid dissociates to release H+ and hydrogencarbonate ions

84
Q

What is the chloride shift

A

Hydrogen carbonate ions move out of the cell chloride ions move into the erythrocytes to balance the charge

85
Q

Formation of haemoglobinic acid

A

To stop blood from becoming acidic from hydrogencarboante building up in the blood hydrogen ions are taken out of solution by associating with haemoglobin to form haemoglobinic acid
- haemoglobin acts as a buffer

86
Q

What happens as haemoglobin releases oxygen

A

haemoglobin becomes available to take up hydrogen ions forming haemoglobinic acid
- where tissue is more active more CO2 is released affecting the haemoglobin

87
Q

What is the Bohr effect

A

Describes the effect an increasing concentration of CO2 has on haemoglobin

88
Q

Describe the Bohr effect

A

CO2 enters RBC forming carbonic acid which dissociates to release H+ ions
- H+ ions effect pH of cytoplasm making it more acidic
- increased acidity alters tertiary structure of haemoglobin and reduces affinty of haemoglobin for oxygen
- haemoglobin can’t hold as much O2 and O2 released into tissues - more respiring tissues - more CO2 so more O2
- more CO2 present haemoglobin becomes less saturated with O2

89
Q

What happens to the haemoglobin dissociation curve if more CO2 is present

A

Shifts downwards and to the right

Module 3 (3 decks)

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