Transcript Revision for Transport in Animals

Transport of Materials to and From Cells
Nutrients – from SMALL INTESTINE to blood – from blood to cells
O2 from the AIR to blood (LUNGS) – from blood to cells
CO2 from cells to blood – from blood to LUNGS – from lungs to AIR
Urea (nitrogenous waste) from LIVER to blood – from liver to KIDNEYS – formation
of urine
Features of a good transport system
A circulating FLUID or MEDIUM to carry materials around the body – BLOOD (Plasma
+ Cells)
A MUSCULAR pump to create pressure that will push the fluid around the body – the
HEART – composed of CARDIAC MUSCLE
Vessels to convey the medium from one region to another – ARTERIES,
CAPILLARIES, and VEINS
EXCHANGE SURFACES – enable useful materials to enter the blood and to leave it
again where they are needed.
TWO circuits (DOUBLE CIRCULATION)– one to pick up O2 and another to deliver O2
to the tissues
Single Circulation – e.g. fish
Blood passes through heart
ONCE per complete circuit
Blood pressure reduced as blood passes through the gill
capillaries - slows down flow to the rest of the body
Limits the rate of delivery of O2 and nutrients to cells and
removal of waste
Efficient for the level of activity of fish but not mammals –
also fish do not maintain their body temperature – need to
respire relatively less compared to mammals
Double Circulation – more efficient - e.g. mammals
Heart is composed of two separate pumps – right side pumps
blood to the lungs to pick up oxygen; the blood is returned to
the left side; the left side pumps oxygenated blood rapidly and
at high pressure to the body; the blood is returned to the right
side
Higher level of activity (energy) and need to maintain their
body temperature at 370C – through respiration
Need to deliver and remove materials to and from cells rapidly
– achieved by delivering blood at high pressure to tissues.
Pulmonary – oxygenates blood & removes CO2
Systemic – oxygenated blood from lungs pumped
rapidly at an increased pressure by the heart
Blood passes through heart
TWICE per complete circuit
Open Circulatory System
Some animals (e.g. insects) have an open circulatory system – the circulating blood is
not contained within vessels all the time. It flows freely through the body cavity and is
in direct contact with the body cells.
In lungs
O2 diffuses into RBCs
Blood oxygenated
Hb + O2
HbO2
CO2 diffuses into alveoli
DOUBLE circulation
2 circuits
Pulmonary & Systemic
Blood passes through
heart twice per
complete circuit
Blood circulated in a
closed circuit – comprising
the heart and blood vessels
- It is a CLOSED circulation
Hb = haemoglobin
In tissues
Blood deoxygenated
HbO2
Hb + O2
O2 diffuses into cells
CO2 diffuses into plasma
CO2
O2
O2
CO2
Pulmonary
circulation
O2
CO2
O2
Systemic circulation
CO2
Functions of Blood
Transport
red blood cells
Defence
Against pathogens - white blood cells - phagocytosis (neutrophils); immune
response - production of antibodies and antitoxins (lymphocytes)
Blood clotting
To prevent blood loss at site of damage & prevent entry of pathogens
(platelets)
1
Larynx
2
Trachea
3
Thymus gland
4
Right lung
5
Left lung
6
Heart
7
Diaphragm
1. Right Auricle
2. Right Ventricle
3.
Brachiocephalic Artery
(Oxygenated blood)
4.
Aortic Arch (Oxygenated
blood)
5.
Pulmonary Artery
(Deoxygenated blood)
6. Left Auricle
7. Interventricular Sulcus
8. Left Ventricle
Anterior view of heart
Activity - Label the diagram of the heart
Labels
A
B
C
D
E
F
G
H
I
J
Right ventricle
Bicuspid (mitral) valve
Tricuspid valve
Right atrium
Pulmonary vein
Pulmonary artery
Vena cava
Aortic semilunar valve
Pulmonary semilunar valve
Chordae tendinae
The cardiac cycle
Cardiac Cycle
Heart relaxed
AV valves are open
Deoxygenated blood from vena cava flows into RA
Oxygenated blood from pulmonary vein flows into LA
Blood passes into ventricles passively
SA node contracts – sends impulses through atria
Atria contract (top downwards) – forces additional blood into ventricles
through AV valves
Blood from RA to LA; blood from LA to LV
Ventricles receive impulses from AVN via Purkinje fibres – ventricles
contract (bottom upwards) – force of blood causes AV valves to close (lub)–
prevents blood flowing back into atria
Blood is forced from RV into PA through pulm semilunar valves and from LV
into aorta through aortic semi lunar valves
Heart relaxes – semilunar valves close due to force of blood (dub)- prevent
backflow from pulm artery and aorta into heart - AV valves open
Atria fill with blood again to start cycle again
Blood from RV to LA
Right ventricle muscle contracts-tricuspid valve closes- pulmonary semi-lunar
opens – blood forced into pulmonary artery – ventricles relax – pulmonary
semilunar valve closes – blood forced to lungs from pulmonary artery - blood
sent to left atrium via pulmonary vein – valves in veins prevent backflow
Atrial
Systole
Ventricular
Systole
Diastole
“DUB”
“LUB”
Cardiac cycle
= 0.8 sec
60/0.8 bpm
= 72 bpm
A
Atrioventricular (bicuspid / mitral) valve(s) closes (“snaps shut”– makes 1st
louder heart sound “LUB”
B
Semilunar valve(s) (aortic valve) opens
C
Semilunar valve(s) closes – makes second softer heart sound “DUB”- shut
due to blood accumulating in their pockets
D
Atriioventricular (bicuspid) valve(s) opens
Week 8
Pressures changes in the aorta, left ventricle and left atrium during one
heartbeat
© Pearson Education Ltd 2008
This document may have been altered from the original
Length of 1 cardiac cycle ~ 0.8 sec
No of beats per minute = 1 x 60/0.8 sec = 75 beats/min
Electrocardiogran (ECG)
Electrodes are placed on the skin over opposite sides of the heart, and the electrical
potentials generated recorded with time. The result is an ECG.
P wave = electrical activity during
atrial systole
QRS complex = electrical activity
during ventricular systole
T wave = ventricular repolarisation
(recovery of ventricular walls)
Q-T interval – contraction time
(ventricles contracting)
T-P interval – filling time –
ventricles relaxed and filling with
blood
Pattern are studied in different conditions and compared to the standard ECG in
order to diagnose heart conditions, such as arrythmias and fibrillation. Fibrillation is
stopped by passing a strong electric current through the chest wall – the heart stops
for up to 5 seconds after which it begins to beat in a controlled way
A normal ECG trace compared with others indicating an unhealthy heart
Regulation of the Heart
•Atria relaxed – fill with blood
•RA with deoxygenated blood from vena
cava
•LA with oxygenated blood from pulm vein
•SAN sends out 72 impulses/min over atrial
wall – atria contract 72 times/min
•Atria contract to force blood into ventricles
•Atria relax
•Impulse reaches AVN
•Delayed momentarily
•Impulse travels through nerve fibres of the
atrioventricular bundle and its branches
into walls of the ventricles
Cardiac Output
•Ventricles contract – from apex upwards to
force blood into arteries
Stroke Volume X Heart Rate = CO
•Oxygenated blood from LV to aorta – to
75 X 70 = 5250 ml/min – Normal
body
Factors that increase SV or HR increase CO •Deoxygenated blood from RV to
SV depends on how much blood enters the pulmonary artery – to lungs (to be
oxygenated)
ventricle during diastole
HR is regulated by several factors –
Chemical(e.g. CO2; pH) and physical ( blood pressure)
Exercise; Stress; Fright
Muscles – greater demand for
O2 and nutrients (glucose) for
energy; increased production of
waste – CO2 and lactic acid;
excess heat produced - need to
be removed. Increase in CO2
detected by chemoreceptors in
aortic arch and carotid artery
Accelerator (sympathetic cardiac)
nerve releases chemical
neurotransmitter (NE) at SAN to
increase rate and force of
contraction of heart to increase
cardiac ouput
Adrenaline is released from
adrenal gland – stimulates heart
(increase rate and force; dilates
blood vessels in muscles to
increase blood flow)
Decelerator (vagus) nerve
releases chemical (acetylcholine)
at SAN to slow heart
Carotid artery
Aortic arch
The pathway followed by the wave of excitation
Capillary – endothelium – large number – large surface area for exchange
Wall - one cell thick – short diffusion distance
Endothelium is continuous throughout circulatory system
Capillary
Vein
Wide lumen; Low pressure
Thin wall - less elastic and less muscular
Valves (semilunar) – prevent backflow
Deoxygenated blood to heart from tissues except pulmonary vein from lungs
Non pulsatile – smooth flow of blood
Artery
Narrow lumen; High pressure
Highly elastic – expand and recoil
Thick muscular wall – to withstand force;
more elastic fibres (recoil)
No valves (except aortic and pulmonary
semilunar at the start)
Oxygenated blood from heart – except
pulmonary artery to lungs
Pulsatile blood flow (expansion + recoil)
Pulse can be felt – e.g. wrist
Blood – a connective tissue
Blood cells are made from stem cells, mainly in the bone marrow and foetal
liver
Plasma (liquid part – 55%) – 90% water + 10% substances
Transports substances around the body
CO2 from cells to lungs; urea from liver to kidneys; hormones;
enzymes; antibodies; fibrinogen; heat
White blood cells (Leucocytes) – 5000 – 7000 per ml of blood
Defence
Lymphocytes (produce antibodies and antitoxins)
Phagocytes – engulf and destroy pathogens (microbes)
Platelets (Thrombocytes) – 200 000 – 300 000 per ml of blood
blood clotting – cell fragments - contain enzymes – released a the
site of a cut – converts soluble blood protein fibrinogen to insoluble
fibrin – forms blood clot – prevent loss of blood and prevent entry
of microorganisms
5 – 6 litres
Red blood cells (Erythrocytes) – 4 -6 million per ml of blood
45% of blood volume (termed the haematocrit) – lower in anaemia
Transport oxygen from lungs to cells
Contain blood group antigens on surface of membrane
Red blood cells (erythrocytes)
Contains haemoglobin (Hb) - formation requires Fe
Hb transports O2 from lungs to cells
Biconcave discs – large surface area for diffusion of O2
No nucleus – more space for Hb
Flexible – squeeze through capillaries in single file
Neutrophils
Defence - phagocytosis
Contain enzymes
Engulf (ingest) microbes and digest them
Lymphocytes
Defence – immune response
Produce antibodies and antitoxins
Killer cells – destroy cells infected with viruses
Platelets
Rupture and release enzyme at site of cut – initiates a
cascade of reactions – converts insoluble blood protein
fibrinogen to insoluble fibrin threads which trap blood
cells and platelets to form a blood clot
Activity -Blood Vessels
1
2
2
1
3
3
4
5
4
6
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5
6
7
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10
E
………………………..
Hole in the Heart
Congenital (at birth) – between atria or
ventricles
Allows mixing of oxygenated and
deoxygenated blood – blood passes
from RA to LA
Some blood does not enter ventricles
Some blood does not enter ventricles
and pulmonary artery
Reduces systolic pressure
Dangerous if not treated
Pressure reduced – some blood
bypasses lungs
Less O2 carried/picked up/loaded
Less respiration – decreased O2
supply to cells – less energy
Weakness; anaemia;
Platelets & Blood Clotting
(Haemostasis)
1
Damage / Cut
2
Vascular spasm (vessels constrict – to reduce
blood flow
3
Platelets become sticky – form a Platelet plug
4
Platelets rupture on contact with air and
damaged tissue - release thromboplastin
(enzyme)
5
Cascade of reactions (involving plasma
proteins (clotting factors)
6
Fibrinogen (soluble) to fibrin (insoluble)
7
Blood cells trapped – CLOT formed
8
Clot tightens (retracts) - fibrin seals open tissue
– hardens into a scab
9
Clot dissolves after blood vessel repair
Heparin prevents clotting normally – inhibits
conversion of prothrombin to thrombin – action of
anticoagulant drugs (e.g. warfarin) used clinically
Thrombosis – clotting in unbroken blood vessel
Stroke – clotting in cerebral blood vessel
Requires
Vitamin K
Streptokinase – enzyme used clinically to dissolve
blood clots in vessels
http://uk.youtube.com/watch?v=rguztY8aqpk
http://www.gwc.maricopa.edu/class/bio202/heart/inthrt.htm
http://www.zerobio.com/videos/sheep_heart_anatomy.html
http://www.vimeo.com/1813369?pg=embed&sec=1813369