8/8/2019 As Blood Transport
1/37
F211
Exchange and Transport
Heart and Circulation
8/8/2019 As Blood Transport
2/37
LO: explain the need for transport systems in multicellular
animals in terms of size, activity and surface area to volume
ratio
All cells need energy, where do they get it from?
How is the energy released?
How do the food molecules and oxygen get to the cells in
simple organisms and complex organisms? How does the organisms activity level influence how fast the
food molecules and oxygen have to get to the cells?
Does the fact that some organisms are ectothermic (cold
blooded) and some are endo thermic (warm blooded) affecthow fast these molecules need to be supplied to cells?
8/8/2019 As Blood Transport
3/37
What are the features of an efficient oxygen and
nutrient molecule transport system?
A fluid medium to carry molecules
A pump to push the fluid round
Exchange surfaces for oxygen and nutrients toenter and leave the blood
Vessels to carry the fluid medium round the
organism Separate circuits to pick up oxygen from the
environment and deliver it to the cells.
8/8/2019 As Blood Transport
4/37
Explain the meaning of the terms single and double
circulation with reference to the systems of fish and mammals
What are the disadvantages of
this system?
Heart cannot pump at highpressure
Reduced blood pressure in
capillaries of gills to reduce
chance of damage
Slow rate of flow in rest of body
Limited rate of delivery of oxygen
and glucose to tissues
Fish have a single circulation
system. Blood flows from the heartto the gills and then on to the
body before returning to the heart
8/8/2019 As Blood Transport
5/37
Explain the meaning of the terms single and double
circulation with reference to the systems of fish and mammals
What are the advantages of themammalian system?
Heart can increase blood pressure
after blood passes through lungs Increased speed of delivery
Increased blood pressure in systemicsystem, oxygen and glucose get totissues quickly
Lower blood pressure in pulmonarysystem decreases the chance ofdamaging capillaries in the lungs
Mammals have double
circulatory systems. One circuit
(pulmonary) takes blood from
the heart to the lungs and back,the other(systemic) takes blood
from heart to body tissues and
back.
8/8/2019 As Blood Transport
6/37
Explain the meaning of the terms single and double
circulation with reference to the systems of fish and mammals
To see how the heart and
circulatory systems haveevolved go to:
http://mhhe.com/biosci/genbio/biolink/j_explorations
/jhbch05.htm
8/8/2019 As Blood Transport
7/37
Learning outcomes
Describe the external and internal structure of
the mammalian heart.
Explain the differences in thickness of the
walls of the different chambers of the heart in
terms of their functions.
8/8/2019 As Blood Transport
8/37
Heart diagrams
Label as much as you can on the diagram
using the labels on the sheet supplied.
8/8/2019 As Blood Transport
9/37
8/8/2019 As Blood Transport
10/37
External view of Heart
8/8/2019 As Blood Transport
11/37
Describe the cardiac cycle with reference to the action of the
valves in the heart.
8/8/2019 As Blood Transport
12/37
For animation of the cardiac cycle and explanation of
the changes in pressure that take place
http://library.med.utah.edu/kw/pharm/hyper
_heart1.html
8/8/2019 As Blood Transport
13/37
Be able to link
changes in pressure
and volume shown on
the graph with the
stages of the cardiac
cycle.
8/8/2019 As Blood Transport
14/37
Control of the Cardiac cycle
Read text book pages 58-59
Make notes on the meaning of:
Myogenic
Sinoatrial nodeAtrioventricular node
Purkyne (Purkinje) tissue
8/8/2019 As Blood Transport
15/37
Control of the cardiac cycle
Non conducting
tissue
8/8/2019 As Blood Transport
16/37
Interpret and explain electrocardiogram (ECG) traces
with reference to normal and abnormal heart activity.
8/8/2019 As Blood Transport
17/37
ECG interpretation
P-R interval (usually 0.12 to 0.2 secs) greater than 0.2 secs means a delay
in the transmission of the excitation wave to the ventricles due to damage
to the AV node or Purkine tissue
QRS complex is usually 0.06 to 0.1 sec in duration, if longer it indicates
problems with the conduction of the excitation wave across the ventricles. Small unclear P waves indicate atrial fibrillation due to damage to the SAN,
this means that the ventricles are not filled during atrial systole, so
ventricle contraction doesnt expel the normal amount of blood.
No regular PQRS pattern discernible indicates fibrillation of the atria and
ventricles, uncoordinated weak contractions of the chambers so thatblood is not pumped out of the heart effectively.
Deep S waves indicate an increase in ventricle thickness due to increase in
blood pressure.
8/8/2019 As Blood Transport
18/37
Interpret and explain electrocardiogram (ECG) traces with reference to
normal and abnormal heart activity.
P shows atrial excitationjust prior to atrial
systole QRS shows ventricle excitation that causes
ventricular systole
T shows repolarisation of the heart muscle
during diastole
Top ECG normal
Any changes to the shape and length of each
section of the trace can indicate heart
abnormalities
Raised ST section indicates heart attack, no
ion pumps workinging to repolarise cells
Fibrillation is unco-ordinated contraction ofeither / or / both atria and ventricles
Hypertrophy: extra muscle growth to
overcome increased blood pressure due to
blockages in blood vessels
8/8/2019 As Blood Transport
19/37
Complete the question on ECG traces
8/8/2019 As Blood Transport
20/37
Explain the meaning of the terms open and closed
circulatory systems with reference to insects and fish
Closed circulatory system
Vertebrates, and a few invertebrates, have a
closed circulatory system. Closed circulatory
systems have the blood closed at all times
within vessels of different size and wall
thickness. In this type of system, blood is
pumped by a heart through vessels, anddoes not normally fill body cavities.
Open circulatory system
The open circulatory system is common to
molluscs and arthropods. Open circulatory
systems (evolved in crustaceans, insects,
mollusks and other invertebrates) pump blood
into a hemocoel with the blood diffusing back to
the circulatory system between cells. Blood ispumped by a heart into the body cavities, where
tissues are surrounded by the blood.
8/8/2019 As Blood Transport
21/37
Describe the structure of arteries,
veins and capillaries
8/8/2019 As Blood Transport
22/37
Describe the structures and functions
of arteries, veins and capillaries
Cut up the table thatyou have been givenand sort it out!
When completedcollect a correct version
Learn the sequence oftissues that make up
the walls of arteries andveins. ie: endothelium,elastic fibres, smoothmuscle, collagen fibres
Make notes on thefunctions of:endothelium, elastic
fibres, smooth muscleand collagen fibres
How does skeletalmuscle help blood flowback to the heart?
What are valves for inveins?
8/8/2019 As Blood Transport
23/37
Features of arteries, veins and
capillariesFeature Arteries Capillaries veins
Wall thickness Thicker than veins Very thin, walls only
one cell thick
Thinner than arteries
Muscle in wall Thick muscle layer NO muscle layer Thin muscle layer
Elasticity of wall Thick layer of elastic
tissue
NO elastic tissue Little elastic tissue
Inner surface Smooth endothelium,
often folded, can
unfold when stretched
Only one layer of cells
made of endothelium
Smooth endothelium,
not folded
Shape of cross section Round round Irregular or flattened
Size of lumen small Tiny (only 7 m across) Larger than artery
Direction of blood flow From heart towards
organs
From arterioles to
venules
From organs back to
heart
Pressure of blood high low low
valves No valves apart from
at exit of ventricles
(semi-lunar valves)
No valves Pocket valves all along
length
8/8/2019 As Blood Transport
24/37
Sequence of tissues in arteries, veins
and capillaries
8/8/2019 As Blood Transport
25/37
Functions of tissues
Endothelium provides a smooth lining that offers little friction to slow down the
passage of blood. It may be folded lining arteries to allow it toexpand when blood surges though and the artery stretches
Elastic fibres-
allow vessels to stretch as high pressure blood flows through; andrecoil to maintain pressure in arteries when heart is in diastole.
Smooth muscle
in arteries and arterioles can be contracted to constrict the vesseland decrease the volume of blood flowing through
Collagen-
forms a strong external layer to withstand high pressure generatedby ventricular systole
8/8/2019 As Blood Transport
26/37
Importance of pocket valves in veins
Because blood pressureis low in veins there is atendency for blood topool due to the effects
of gravity. Valves prevent blood
flowing backwards
Veins are situatedbetween skeletal muscle,
when this contracts itsqueezes blood up theveins and assists in itsreturn to the heart
8/8/2019 As Blood Transport
27/37
Explain the differences between blood, tissue
fluid and lymph.Feature Blood Tissue fluid Lymph
Cells Erythrocytes(red) Leucocytes
(white) and platelets
phagocytes lymphocytes
Proteins Hormones and plasma
proteins
Hormones and protein
secreted by body cells
Few proteins
Fats Some transported as
lipoproteins (HDL, LDL)
NONE More than in blood (absorbed
from lacteals in small intestine)
Glucose 80-120mg per 100cm3 Less than in blood Gets
absorbed by cells
Less than in blood and tissue
fluid
Amino acids More than in other fluids Less than in blood Gets
absorbed by cells
Less than in blood and tissue
fluid
Oxygen More than in other fluids Less than in blood Gets
absorbed by cells
Less than in blood and tissue
fluid
Carbon dioxide Little More than in blood.Gets
absorbed by cells
More
8/8/2019 As Blood Transport
28/37
Describe how tissue fluid is formed
from plasma.
Arteries branch into arterioles andthen into capillaries around thetissues of organs
The contractions of the heartmaintain some pressure in thecapillaries (hydrostatic pressure)
This squeezes fluid out betweenthe endothelial cells of thecapillaries
The fluid contains oxygen, aminoacids and glucose; but no cellsapart from a few phagocytes andno plasma proteins which are toolarge to go through the pores
8/8/2019 As Blood Transport
29/37
Exchange in the capillary bed
Tissue fluid bathes the cells Nutrients (glucose, mineral ions
and amino acids) and oxygenare taken into cells by diffusion,
facilitated diffusion and activetransport
Waste such as CO2 and urea areremoved from cells by similarprocesses
Tissue fluid must now return tothe circulatory system tomaintain blood volume
8/8/2019 As Blood Transport
30/37
How does the fluid return to the
blood? Plasma proteins which remain in the
blood give blood a lower waterpotential than tissue fluid so watertends to flow back into thecapillaries down a water potentialgradient, solutes diffuse down theirconcentration gradients.
At the arteriole end of the capillaryhydrostatic pressure is greater thanosmotic pressure (solute potential)so there is net outflow from thecapillary
At the venule end of the capillarythe hydrostatic pressure hasdropped considerably due to fluidleaving the blood, it is now lowerthan the osmotic pressure(solutepotential);so there is net inflow tothe capillary
8/8/2019 As Blood Transport
31/37
Importance of the lymphatic system
Without the lymphatic system tissuefluid could accumulate and causeoedema
The lymph nodes contain largenumbers of phagocytic lymphocytesthat engulf and kill bacteria. Theyare part of the immune system
8/8/2019 As Blood Transport
32/37
8/8/2019 As Blood Transport
33/37
8/8/2019 As Blood Transport
34/37
Uptake of oxygen by haemoglobin
Rate of uptake of oxygen depends onthe partial pressure of oxygen
Partial pressure can be thought of asthe amount of a particular gas in amixture of gases measured in kPa
At low partial pressures it is difficult for
oxygen molecules to associate withhaemoglobin; it is hard for the firstoxygen molecule to get in to thecomplex and reach the haem group.
Once one oxygen molecule is in, the Hbmolecule changes shape and this makesit easier for more oxygen to get in.
Second and third O2 moleculesassociate quite easily To get the fourth one in and get almost
100% saturation the partial pressureneeds to be very high
8/8/2019 As Blood Transport
35/37
Uptake of oxygen by haemoglobin
This means that in areaswhere the partial pressureof oxygen is high,such asthe lungs, haemoglobin is
almost saturated. In areas where the partial
pressure of oxygen is low,such as respiring tissues,the oxygen dissociates from
the haemoglobin easily andthen diffuses out of theblood plasma to the cellsthat need it.
8/8/2019 As Blood Transport
36/37
Uptake and release of oxygen by
haemoglobin
faet
Foetal haemoglobin has ahigher affinity for oxygenthan adult haemoglobin
As the mothers blood
flows through theplacental tissue the PO2 islow so the oxygendissociates from thehaemoglobin
The foetal haemoglobinpicks up the releasedoxygen.
8/8/2019 As Blood Transport
37/37
Oxygen availability at altitude
The % of oxygen in the air is the same as at sea level but theatmospheric pressure is much lower
This means that fewer molecules of oxygen are inhaled per
breath, so % saturation of haemoglobin in the lungs is greatly
reduced
Lack of oxygen at altitude results in heavy breathing, and
increased heart rate as the body tries to maintain normal
levels of oxygen supplied to tissues.
Dizziness, headaches, nausea, increasing confusion, inability
to walk straight may follow
In extreme cases this can turn into HACE (high altitude
cerebral edema) or HAPE (high altitude pulmonary edema)
which are potentially life threatening conditions unless the
person descends to an area where oxygen availabilty is higher
Top Related