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Biology > 3.2 - Transport in Animals > Flashcards

3.2 - Transport in Animals Flashcards

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1
Q

describe the needs for transport systems in multicellular organisms (3)

A
  • high metabolic rate: more 02 needed for respiration and removal of CO2 = diffusion alone not enough
  • small SA:V ratio = diffusion distance too large
  • need to transport substances produced to parts in the body that need it
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2
Q

what do circulatory systems typically consist of?

A
  • a heart / some such pumping mechanism
  • fluid in which substances are transported
  • vessels in which fluid flows
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3
Q

why do unicellular organisms not need a specialised transport system?

A
  • large SA:V
  • low metabolic rate
  • short diffusion distance
  • less need to O2 and CO2 removal
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4
Q

types of circulatory systems?

A
  • open and closed
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5
Q

which organisms have an open circulatory system?

A

invertebrates, insects, molluscs

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6
Q

which organisms have a closed circulatory system?

A

vertebrates, mammals, many others

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7
Q

what is a mass transport system?

A
  • when substances are transported in a mass of fluid
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8
Q

describe an open circulatory system, what is the body cavity called in open circulatory systems?

A
  • few short vessels
  • fluid pumped straight from the heart into the body cavity
  • HAEMOCOEL
  • transport medium in hemocoel is under low pressure
  • fluid comes into DIRECT CONTACT with tissue and cells
  • fluid returns to the heart through an open-ended vessel
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9
Q

what is open system (we need to know insects) blood called?

A

haemolymph

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10
Q

describe the circulatory system in open system (we need to know insects)

A
  • haemolymph doesn’t carry O2 or CO2
  • instead carries food and nitrogenous waste
  • directly bathes tissue,, diffusion occurs
  • when heart relaxes, haemolymph sucked back into heart via pores called OSTIA
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11
Q

what causes haemolymph to move around organisms?

A

movement of organism

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12
Q

disadvantages of open circulatory system?

A
  • haemolymph circulates but STEEP DIFFUSION distance cannot be maintained for efficient diffusion
  • volume of haemolymph flowing to particular tissue can not be varied to meet changing demands
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13
Q

describe a closed circulatory system

A
  • within vessels at all times
  • high pressure/speeds
  • series of progressively smaller vessels
  • not in direct contact with cells
  • instead diffuses across the capillary wall
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14
Q

advantage of closed circulatory system?

A
  • amount of blood can be varied by WIDENING / NARROWING blood vessels
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15
Q

differences between open and closed circulatory system?

A

+ open: haemolymph bathes organs
+ open: no distinction between blood and tissue fluid ‘interstitial fluid’
+ open: blood pumped into body cavity (haemocoel)
+ open: no capillary system
+ open: no gases transported
+ open: no respiratory pigment found in haemolymph
+ open: volume of blood not controlled
+ open: blood flow slow/low pressure

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16
Q

where are single closed circulatory systems found?

A
  • many fish

- annelid worms

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17
Q

describe circulation through a single closed circulatory system

A
  • blood travels from heart to whole body, then heart

- ONLY ONE CIRCUIT for complete circulation

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18
Q

describe why single closed circulatory systems are not efficient?

A
  • blood flows through two sets of capillaries
  • first: gases are exchanged
  • second: subatances are exchanged
  • by the time it reaches heart again, blood is at a low pressure, reaches heart slowly
  • limits efficiency of exchange
  • activity = low
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19
Q

what are an exception to inactive organisms with a single closed circulatory system?

A

fish hehe

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20
Q

where are double closed circulatory systems found?

A
  • birds

- mammals

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21
Q

describe circulation through a single closed circulatory system

A

two separate circulations
1. Pulmonary circulation- Blood pumped from heart to lungs to pick up O and drop off CO2. Returns to heart.
second: blood to heart to body to heart
2. Systemic circulation- blood flows through hear and is pumped out all around body before returning again.
(Most efficient transport system)

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22
Q

how does blood maintain a high pressure in a double closed circulatory system

A

only passes through one capillary network

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23
Q

name the main blood vessels in mammals

A

arteries, arterioles, veins, venules, and capillaries

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24
Q

describe the structure and function of the inner layer of artery walls

A
  • tunica intima: thin layer of elastic tissue
  • allows wall to stretch (within limits allowed by collagen) and recoil TO MAINTAIN BLOOD PRESSURE
  • evens out surges of blood to give continuous flow
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25
Q

describe the structure and function of the middle layer of artery walls

A

tunica media: thick layer of smooth muscle

- contracts and relaxes to change size of lumen

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26
Q

describe the structure and function of the outer layer of artery walls

A

tunica adventitia: thick layer of collagen and elastic tissue

  • provides strength to withstand high pressures
  • structural support
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27
Q

describe the structure and function of the endothelium of arteries

A

lining of artery

- smooth to reduce resistance of blood

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28
Q

describe the structure of arteries (visible)

A
  • contain elastic fibres, smooth muscle, and collagen
    INSIDE TO OUT
    lumen, endothelium, elastic fibres, smooth muscle, collagen
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29
Q

function of arteries?

A
  • carry oxygenated blood away from heart
  • EXCEPT pulmonary artery- carries deoxygenated blood to lungs
  • AND umbilical artery- carries deoxygenated blood from the fetus to placenta
30
Q

describe structure and function of arterioles

A

distribute blood from arteries to capillaries

  • more smooth muscle / less elastin
  • CAN CONSTRICT/DILATE TO DIVERT FLOW OF BLOOD TO SPECIFIC ORGANS
  • smooth muslce contracts: constricts vessel, prevents blood from flowing into the capillary bed
  • VASOCONSTRICTION, and opposite
31
Q

the sequence of blood vessels from/back to heart?

A

heart - artery - arteriole - capillary - venule - vein - heart

32
Q

describe structure and function of capillaries

A

allow exchange of material between blood and tissue fluid

  • narrow lumen, 7-8.5μm, same as RBC. squashed against wall when exchange takes place
  • wall consists of a single layer of endothelium
  • leaky walls with holes, allow blood plasma and dissolved substances to leave
33
Q

adaptations of capillaries?

A
  • provide a large SA
  • total cross sectional ara of capillaires > arteriole supplying them so rate of blood flow falls
    + this slow movement gives more time for exchange
  • walls are single endothelial cell think, thin layer for diffusion
34
Q

describe function of veins/venules

A

carry blood away from cells to heart, deoxygenated, except pulmonary vein and umbilical vein
- capillaries then venules then veins

35
Q

describe structure and function of veins

A
  • no pulse
  • 60% of blood in veins at any time
  • walls contain lots of collagen and little elastic fibres
  • wide lumen
  • endothelium, so blood flows easily
36
Q

describe the features of veins that allow blood to flow in one direction

A
  • one way valves at intervals: flaps/infoldings
  • big veins closer to big muscles, muscle contraction squeezes the veins
  • breathing movements of chest act as pump for veins , changes in pressure
37
Q

How is deoxygenated blood returned to the heart?

A

-deoxygenated blood flows from capillaries to venules to larger veins.
Finally it reaches the two main vessels, carrying deoxy blood back to heart:
- Inferior vena cava (from lower body parts)
-superior vena cava (from head+upper body).
The blood is under low pressure and needs to move against gravity so there are adaptations to help this.

38
Q

What is the blood?

A

The main transport medium of the human circulatory system. Also considered a type of connective tissue.

  • consists of plasma (a yellow liquid) which carries dissolved glucose, amino acids, mineral ions, hormones and plasma proteins.
  • plasma =93% water. (Therefore Polar solvent)
  • Has rbc(most) and wbc( least) and platelets.
  • plasma makes up 55% of the blood by volume. (Rest is made up by stuff it carries^)
39
Q

What are the main plasma proteins and their roles?

A
  1. Albumin- important for maintaining osmotic potential of blood.
  2. Fibrinogen- important in blood clotting.
  3. Globulins- involved in transport and the immune system.
40
Q

What are platelets?

A

Aka thrombocytes
Fragments of large cells called megakaryocytes found in the red bone marrow.
- involved in clotting mechanism of blood.
- carried by the plasma in the blood.

41
Q

Functions of the blood

A
  • contributes to the maintenance of body temp. (Thermoregulation)
    -Acts as a buffer, minimising pH changes.
    Transport of:
  • oxygen to and carbon dioxide from respiring cells.
  • digested food from small intestine.
  • nitrogenous waste products from cells to excretory organs.
  • hormones.
  • food molecules from storage components to cells that need.
  • platelets to damaged areas.
  • cells/antibodies involved in immune system.
42
Q

What is oncotic pressure?

A

The tendency of water to move into the blood by osmosis, causes by proteins like albumin creating high solute concentration in plasma

43
Q

What is hydrostatic pressure?

A

The pressure from the surge of blood that occurs every time the heart contracts, by fluid pushing against the blood vessel wall

44
Q

Explain the osmotic effect of the plasma proteins.

A
  • The plasma proteins (especially albumin) give the blood in the capillaries high solute potential so therefore low water potential as compared to surrounding fluid.
  • due to oncotic pressure, water has a tendency to move into the blood in the capillaries via osmosis from the surrounding fluid.
45
Q

Explain the movement into and out of the capillaries. (Formation of tissue fluid)

A

At the arterial end of capillaries:
- blood entering from arterioles has high hydrostatic pressure. It is higher than the oncotic pressure attracting water in by osmosis so fluid is squeezed out. This fluid fills spaces between cells and is called tissue fluid, exchange occurs between tissue fluid and cells
At venous end:
- As blood moves through capillary, hydrostatic pressure decreases as fluid has moved out. Oncotic pressure= greater than hydrostatic so water moves back in via osmosis.
(By the time blood returns to veins, 90% of tissue fluid back in blood vessels)

46
Q

What is tissue fluid? made up of?

A

The fluid that fills spaces between cells, after being forced out of arterial end of capillaries
Same composition as plasma but without RBCs and plasma protein.
Diffusion takes place between the blood and the cells through the tissue fluid.

47
Q

What is lymph?

A

Not all the tissue fluid returns to the capillaries.
10% drains into a system of blind-ended tubes called lymph capillaries. Here it is known as Lymph.
- the lymph capillaries join up to form larger lymphatic vessels.

48
Q

What is the composition of lymph?

A
  • similar composition to plasma/tissue fluid but has less O2 and nutrients.
  • also contains fatty acids, which have been absorbed into lymph from villi of small intestines.
49
Q

How is lymph fluid transported and to where?

A

Transported through the lymphatic vessels by the squeezing of body muscles.

  • one way valves prevent backflow.
  • eventually it returns into the blood, flowing into the right and left subclavian veins (under the clavicle/collar bone).
50
Q

What are lymph nodes and lymphocytes? Function?

A

Along the lymph vessels are the lymph nodes.
Lymphocytes build up in the lymph nodes when necessary and produce antibodies which are then passed into the blood.
- lymph nodes also intercept bacteria from the lymph, which are ingested by phagocytes in the nodes.
- if tissue infected, capillaries become leaky, direct bacteria to lymph nodes

51
Q

What do enlarged lymph nodes show?

A

A sign that the body is fighting of an invading pathogen.

This is why doctors examine the neck, armpits, stomach or groin as these are the sites if major lymph nodes/glands.

52
Q

What is the heart (mammals)? what is the sternum?

A

A complex, four chambered muscular bag found in the chest enclosed by the ribs and sternum (large vertical bone holding ribs together)

53
Q

describe the external features of the mammalian heart?

A
  • form dark-red muscle called cardiac muscle
  • 2 ventricles, 2 smaller atria
  • coronary arteries lay over surface of cardiac muscle, supply oxygenated blood to heart muscle
54
Q

what is angina and what causes it? what else can this cause?

A

angina: attacks of chest pain caused by restricted blood/oxygen flow to heart
- myocardial infarction

55
Q

what surrounds the heart that stops it from ‘over stretching’?
what is this called?

A
  • inellastic pericardial membranes

- over distending

56
Q

describe the structure of cardiac muscle?

A
  • many fibres that branch and produce cross-bridges
  • spread stimulus around heart
  • ensure muscle san produce a squeezing action rather than a reduction in length
  • numerous mitochondria to supply energy for contraction
  • cells separated by INTERCALATED DISCS which facilitate synchronised conraction
  • each cell is divided into contractile units called SARCOMERES
57
Q

What is systole?

A
  • atria contract (atrial systole).
  • FOLLOWED BY ventricles contract (ventricular systole).
  • pressure in heart increases dramatically as blood is forced into lungs then out of heart
  • volume and pressure of blood are low at the end of systole.
  • blood pressure in arteries is at maximum AS BLOOD IS IN THE ARTERIES
58
Q

What is diastole?

A
  • the heart relaxes after blood
  • atria and then the ventricles fill with blood.
  • volume increases.
  • pressure decreases.
  • blood pressure in arteries is at minimum.
59
Q

where is the SAN?
what is the SAN?
what does it do?

A
  • top of right atrium, near where vena cava empties blood into R.A
  • sino-atrial node
  • small patch of tissue that generates electrical activity
  • creates wave of excitation 55-80 times a minute
  • causes the atria to contract and so initiating a heartbeat.
  • heart’s natural pacemaker
60
Q

where is the AVN?
what is the AVN?
why do we need it?
what does it do?

A
  • at the top of the interventricular septum
  • atrioventricular node
  • after the atrial systole, the tissue at the base of the atria is unable to conduct so impulse cannot go directly to ventricle walls SO ONLY ROUTE TO VENTRICLES
  • the wave of excitation is delayed in the node, allowed atria to finish contracting and blood to flow to ventricles
  • it then stimulates the bundle of his.
61
Q

where is the bundle of His?
what is it made of?
what does it do?

A
  • below AVN, runs down the interventricular septum
  • bundle of contucting tissue with two branches that end with purkyne fibres
  • passes impulse from AVN to left and right branches
  • impulse travels down septum to base (apex)
62
Q

What happens at the apex (electrical impulse)?

A
  • The purkyne fibres spread out over the walls of the ventricles on both sides (like vines)
  • the spread of excitation triggers the contractions of the ventricles, starting at the apex, then up
  • contractions starting at the apex allows more efficient emptying of ventricles.
63
Q

Explain the route of blood when it enters the heart till it leaves.

A
  1. Deoxy 🩸enters right atrium from the vena cavas. As it flows in, pressure builds up till tricuspid valve opens and allows blood into right ventricle.
  2. When atrium and ventricle are filled, atrium contracts, blood all forced to r ventricle.
  3. R ventricle starts contracting, t valve closes. Pumps deoxy 🩸through semilunar valves into pulmonary artery (takes to lungs).
  4. At same time, oxy🩸from lungs enters left atrium from pulmonary vein. As pressure builds b valve opens. L ventricle also fills with 🩸.
  5. Atrium contracts, forces all blood into L ventricle. L ventricle contracts, b valve closes, oxy 🩸 pumped through s valves into aorta to whole body.
64
Q

Role of tendinous cords in heart?

A

Make sure that when the atrioventricular valves close they aren’t turned inside out by the pressures exerted when the ventricles contract.

65
Q

Why are lymphatic capillaries called blind-ended?

A

closed at one end

66
Q

Describe the route of blood through the heart (SAN/AVN)

A
  • blood enters heart through vena cava
  • blood enters right atrium
  • blood travels through tricuspid valve
  • blood enters right ventricle
  • SAN impulse sent
  • atria contract (atrial systole)
  • AVN impulse sent
  • impulse travels down septum and then up ventricles
  • ventricles contract
  • blood travels through pulmonic valve into lungs
  • blood travels into alveoli, exchange takes place
  • blood reenters heart through pulmonary vein
  • blood travels through bicuspid valve
  • SAN impulse sent
  • atria contract
  • blood enters left ventricle
  • AVN impulse sent
  • impulse travels down septum and up ventricles
  • ventricles contract
  • blood travels through aortic valve out of heart
  • blood travels through body
67
Q

why does the contraction of the heart need to be coordinated the way it is (SAN/AVN)?

A
  • heart muscle is myogenic (initiates its own contractions)
  • atrial/ventricular muscles each have their own natural frequency of contraction
  • ATRIAL MUSCLE tends to contract AT A HIGHER FREQUENCY
  • VENTRICULAR MUSCLE tends to contract AT A LOWER FREQUENCY
  • if contractions not synchronised, leads to FIBRILLATION
68
Q

what is fibrillation and what causes it?

A
  • uneven, often very fast beating of the heart

- caused by the unsynchronised beating of different heart muscles

69
Q

describe the action of the semilunar valves curing the cardiac cycle

A
  • Before ventricular contraction, the pressure in the major arteries is higher than the pressure in the ventricles.
  • This means that the semilunar valves are CLOSED
  • Ventricular systole raises the blood pressure in the ventricles very quickly.
  • Once the pressure in the ventricles rises above the pressure in the major arteries, the semilunar valves are pushed open.
  • The blood is under very high pressure, so it is forced out of the ventricles in a powerful spurt.
  • Once the ventricle walls have finished contracting, the heart muscle starts to relax (diastole).
  • Elastic tissue in the walls of the ventricles recoils.
  • This stretches the muscle out again and returns the ventricle to its original size.
  • This causes the 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.
  • The semilunar valves are pushed closed by the blood collecting in the pockets of the valves.
  • This prevents blood from returning to the ventricles.
  • The pressure wave created when the left semilunar valve closes is the ·pulse’ that we can easily feel at the wrist or neck.
70
Q

describe the action of the atrioventricular valves during the cardiac cycle

A

After systole, the ventricular walls relax and recoil (see Figure 2).
• The pressure in the ventricles rapidly drops below the pressure in the atria.
• Blood in the atria pushes the atrioventricular valves open.
• Blood entering the heart flows straight through the atria and into the ventricles.
• The pressure in the atria and the ventricles rises slowly as they fill with blood
• The valves remain open while the atria contract, but close when the atria begin to relax.
• This closure is caused by a swirling action in the blood around the valves when the ventricle is full
• As the ventricles begin to contract (systole), the pressure of the blood in the ventricles rises.
• When the pressure rises above that in the atria, the blood starts to move upwards.
• This movement fills the valve pockets and keeps them closed.
• The tendinous cords attached to the valves prevent them from turning inside out.
• This prevents the blood from flowing back into the atria.

71
Q

how long does the cardiac cycle last?

A

about 0.8 seconds

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