1. Biology, 9th ed, Sylvia Mader
Chapter 34
Circulatory Systems

2. Transport in Vertebrates Transport in Humans
Outline
Transport in Vertebrates
Transport in Humans
Heartbeat
Vascular Pathways
Blood Pressure
Blood
Components
Clotting
Transport in Invertebrates
Open versus Closed Circulatory Systems

3. Transport in Humans Human Heart Cone-shaped
Size of a fist-14cm long and 9cm wide
Inner surface is lined with endocardium
Thick muscular organ (special cardiac fibers)-myocardium
Lies within the pericardium, a thick membranous sac that secretes a lubricating liquid.

4. Thoracic cavity

5. Heart-lies behind the sternum and between lungs.

6. External Heart Anatomy

7. Human cardiovascular system includes two major circular pathways:
Vascular Pathways
Human cardiovascular system includes two major circular pathways:
Pulmonary Circuit
Takes oxygen-poor blood to the lungs and returns oxygen-rich blood to the heart
Systemic Circuit
Takes blood throughout the body from the aorta to the vena cava

8. Path of Blood

9. Human Heart: Gross Anatomy
Septum separates heart into left & right halves
The heart has four chambers
Upper two chambers are the atria
Thin-walled
Receive blood from circulation
Lower two chambers are the ventricles
Thick-walled
Pump blood away from heart

10. Valves open and close to control blood flow through heart
Human Heart: Valves
Valves open and close to control blood flow through heart
Atrioventricular valves (between the atria and ventricles
Tricuspid
Bicuspid
Semilunar valves (between the ventricles and their attached vessels)
Pulmonary
Aortic

11. Internal View of the Heart

12. Cross-section of the heart

13. Transport in the Vertebrates
All vertebrates have a Closed Circulatory System
Heart pumps blood to capillaries
Gases and materials diffuse to and from nearby cells
Vessels return blood to heart without it contacting tissues
Oxygen-poor blood never mixes with oxygen-rich blood (in humans)
Vertebrate vessels:
Arteries - Carry blood away from heart
Arterioles – Lead to capillaries
Capillaries - Exchange materials with tissue fluid
Venules - Lead to veins
Veins - Return blood to heart

14. Transport in Humans Blood returning to heart from systemic circuit
Enters right atrium
Right atrium pumps through tricuspid valve to right ventricle
Right ventricle pumps blood through pulmonary valve to the pulmonary circuit
Blood returning to heart from pulmonary circuit
Enters left atrium
Left atrium pumps through mitral valve to left ventricle
Left ventricle pumps blood through aortic valve to the systemic circuit

15. Blood Flow Through the heart

16. Cardiac Cycle-70 beats/min 100,000 x a day or 40 million x a year
A single cardiac cycle is made up of the events associated with one heart beat. Each cardiac cycle takes about 8 tenths of one second.
During each cardiac cycle pressure changes occur within the chambers of the heart as they relax and contract.
As the chambers relax, they fill with blood, diastole. When the chambers contract, this is called systole.

17. Cardiac cycle
When the AV-opens-blood flows into the ventricles from the atria (semilunar valves are closed).
Atrial contraction results from a series of events beginning with the spread of nerve impulses from the SA-node across the walls of the atria.
Ventricular filling is completed by atrial systole.
Impulses from the AV-node travels along the ventricular conduction fibers leading to contraction of the ventricles.

18. Heartbeat
In ventricular systole, increased pressure forces the AV valves closed, “Lub” semilunar valves open and blood is ejected from the ventricles.
Ventricular diastole, pressure in the ventricles decrease and blood in the aorta and pulmonary flows back toward the chambers, causing these valves to close “dub”.
Ventricular pressure falls below that of the atria, AV valves open and cycle begins again.

19. Heartbeat P- Atrial depolarization/systole
Electrocardiogram (ECG) Fluids contain ions that conduct electrical currents, electrodes placed on the skin are connected to a instrument that detects electrical changes of the myocardium.
P- Atrial depolarization/systole
QRS- Ventricular depolarization
T-wave- Ventricular repolarization

20. Conduction System of the Heart

21. One way venous valves
During muscle contraction, venous diameter decreases, and venous pressure rises. The increase in pressure forces the flow toward the heart.

22. Cross Section of a Valve in a Vein

23. Skeletal muscle contraction pushes blood in the veins toward the heart
Blood Pressure
The beat of the heart supplies pressure that keeps blood moving in the arteries
Systolic Pressure results from blood forced into the arteries during ventricular systole
Diastolic Pressure is the pressure in the arteries during during ventricular diastole
Skeletal muscle contraction pushes blood in the veins toward the heart
Blood pressure
Normally measured with a sphygmomanometer on the brachial artery
Expressed in the form: Systolic “over” Diastolic

24. Transport in Invertebrates
Small aquatic animals with no circulatory system
May rely on external water in gastrovascular cavity to service cells
Roundworms and other pseudocoelomates
Use a fluid-filled body cavity as a means of transporting substances
Fluid-filled cavity can also act as a hydrostatic skeleton
Animals that have a rigid skeleton
May still rely on body fluids for the purpose of locomotion
Bivalves pump hemolymph into the foot for digging into mud

25. Aquatic Organisms Without a Circulatory System

26. Open vs. Closed Invertebrate Circulation
Two types of circulatory fluids:
Blood - contained within blood vessels
Hemolymph - flows into hemocoel
Open Circulatory System
Heart pumps hemolymph via vessels
Vessels empty into tissue spaces

27. Open vs. Closed Circulatory Systems

28. Transport in Birds and Mammals

29. Comparison of Circulatory Circuits in Vertebrates

30. Comparison of Circulatory Pathways
Fish - Blood flows in single loop
Single atrium and single ventricle
Amphibians - Blood flows in double loop
Two atria with single ventricle
Other vertebrates - Blood flows in a double loop
Heart divided by septum into separate sides

31. Blood: Homeostasis Functions
Transports substances to and from capillaries for exchange with tissue fluid
Guards against pathogen invasion
Regulates body temperature
Buffers body pH
Maintain osmotic pressure
Clots prevent blood/fluid loss

32. Lack a nucleus and contain hemoglobin
Red Blood Cells
Small, biconcave disks
Lack a nucleus and contain hemoglobin
Hemoglobin contains
Four globin protein chains
Each associated with an iron-containing heme
Manufactured continuously in bone marrow of skull, ribs, vertebrae, and ends of long bones

33. Most types larger than red blood cells
White Blood Cells
Most types larger than red blood cells
Contain a nucleus and lack hemoglobin
Important in inflammatory response
Neutrophils enter tissue fluid and phagocytize foreign material
Lymphocytes (T Cells) attack infected cells
Antigens cause body to produce antibodies

34. Composition of Blood

35. Blood clot consists of:
Platelets
Platelets
Result from fragmentation of megakaryocytes
Involved in coagulation
Blood clot consists of:
Red blood cells
All entangled within fibrin threads

36. Blood Clotting

37. Capillaries very narrow – Tiny RBCs must go through single file
Capillary Exchange
Capillaries very narrow – Tiny RBCs must go through single file
Wall of capillaries very thin to facilitate diffusion of nutrients, gasses and wastes
Oxygen and nutrients exit a capillary near the arterial end
Carbon dioxide and waste molecules enter a capillary near the venous end

38. Capillary Exchange

39. Capillary Bed

40. Transport in Invertebrates Transport in Vertebrates
Review
Transport in Invertebrates
Open versus Closed Circulatory Systems
Transport in Vertebrates
Transport in Humans
Heartbeat
Vascular Pathways
Blood Pressure
Cardiovascular Disorders
Blood
Components
Clotting

41. Biology, 9th ed, Sylvia Mader
Chapter 34
Circulatory Systems