1. Lecture 6. Transport/Circulation
Functions of the Circulatory System:
–
transport
–
defense
–
regulation

2. Animals without Circulatory System
protozoans
sponges
flatworms cnidarians

3. •
a single-celled protist living in water has a sufficient
surface area of plasma membrane to service its entire
volume
•
the gastrovascular cavity of hydra opens to the
exterior, both outer and inner layers of cells are
bathed in water

4. •
in cnidarians like Aurelia, the products of digestion in
the gastrovascular cavity are directly available to the
cells of the inner layer
•
only a short distance to diffuse to the cells of the
outer layer

5. •
flat body = way to maximize exposure to the
surrounding medium

6. – most organisms
have extensively
folded or
branched internal
surfaces specialized
for exchange with
the environment
– the circulatory
system shuttles
material among
all the exchange
surfaces within the
animal

7. Internal Fluid Environment
• cellular cytoplasm in unicellular animals
protozoans

8. Internal Fluid Environment
• multicellular animals

9. Two Types of Circulatory System
•
Two types of circulatory systems
•
Closed – heart pumps blood in a network of
blood vessels and capillaries
•
Open – heart pumps haemolymph into
tissue spaces

10. Two Types of Circulatory System
insects, other arthropods, earthworms, squids,
most mollusks octopuses, vertebrates

11. Plan and Parts of Vertebrate Circulatory System
• often called the cardiovascular system
• the heart consists of one atrium or two atria, and
one or two ventricles
• arteries, arterioles, veins, venules, and capillaries
• blood

12. Plan and Parts of Vertebrate Circulatory System
•
The Vertebrate Circulatory System
•
Closed type
•
Heart :
•
Atrium – receive blood from circulation
•
Ventricle – pumps blood to blood vessels

13. Plan and Parts of Vertebrate Circulatory System
•
The Vertebrate Circulatory System
•
Blood vessels :
•
Artery – brings blood AWAY from the heart
•
Arteriole – leads to capillaries
•
Capillary – where gas exchange takes place
•
Venule – leads to vein
•
Vein – brings blood TO the heart

15. – two-chambered heart
– subsidiary chambers:
CA sinus venosus (SV),
Artery conus arteriosus (CA)
SV
– blood circuit: single
circuit

16. – three-chambered
heart
– blood circuit: double
circuit
Vein Artery

17. Heart of an Amphibian with Lungs
Fig. 31.11

18. •
Reptiles also have double
circulation with
pulmonary (lung) and
systemic circuits
•
reptilian heart is three-
chambered (except for
crocodiles)
•
ventricle is partially
divided

19. – four-chambered
heart
– crocodilians, birds,
and mammals
– blood circuit: double
circuit
Vein Artery

20. Human Heart
(Bicuspid or mitral valve)
(Tricuspid valve)

21. Coronary System

23. The Cardiac Cycle
Systole - contraction Diastole - relaxation

25. •
cardiac output (5.25 L/min) depends on two
factors:
–
the rate of contraction or heart rate (number
of beats per second)
–
stroke volume (75 mL), the amount of blood
pumped by the left ventricle in each
contraction

26. •
the heart sounds we can hear with a stethoscope
are caused by the closing of the valves
–
sound pattern is “lub-dup, lub-dup, lub-dup”
–
“lub” is created by the recoil of blood against
the closed AV valves
–
“dup” is the recoil of blood against the
semilunar valves

27. •
the impulses generated during the heart cycle
produce electrical currents that are conducted
through body fluids to the skin
•
the currents can be detected by electrodes and
recorded as an electrocardiogram (ECG or
EKG).

28. The control of heart rhythm

29. Fig. 31.14

30. –
two sets of nerves (sympathetic and
parasympathetic) affect heart rate with one
set speeding up the pacemaker and the other
set slowing it down
–
the pacemaker is also influenced by
hormones
–
rate of impulse generation by the pacemaker
increases in response to increases in body
temperature and with exercise

31. The structure
of blood
vessels

32. 32
Blood flow in veins

33. The
interrelationship
of cross-
sectional area of
blood vessels,
blood flow
velocity, and
blood pressure.

34. Measurement of blood pressure
Makes use of a sphygmomanometer and the brachial artery
•
Systolic pressure - peak pressure in the arteries, which occurs near the end
•
of the cardiac cycle when the ventricles are contracting
Dyastolic pressure - minimum pressure in the arteries, which occurs near the
•
beginning of the cardiac cycle when the ventricles are filled with blood

35. Changes in blood pressure
Varies within the day due to circadian rhythm
•
Also change due to stress, nutrition, exercise,
•
drugs, disease, and simply standing up
Hypertension – when arterial pressure is abnormally
•
high
Hypotension – when arterial pressure is abnormally low
•

36. Blood flow in capillary
beds

37. Fluid exchange between capillaries and the interstitial fluid

38. The Blood

40. •
Hemophilia – inability to clot blood
– a sex-linked trait
•
Hemophilia A – clotting factor VIII deficiency
•
Hemophilia B – clotting factor IX deficiency