1. The Circulatory System

2. Importance of Circulatory System
Carry nutrients to cells
Carry waste away from cells
Transport dissolved gasses
Transport chemical messages (hormones)
Regulate temperature
Highway for cells of the immune system
Around the world 2.5 equator ( km circumference)

3. 3 Fundamental Features
A fluid that transports material throughout the body
BLOOD
A network of hollow tubes in which the blood circulates
BLOOD VESSELS
A pump that pushes the blood through the tubes
HEART

4. BLOOD AND BLOOD VESSELS

5. Blood 70 kg person has ~ 5L of blood
Blood is a “fluid” tissue referred to as connective tissue due to its ability to link all cells and organs in the body.

6. The Components of Blood
Plasma
Red Blood Cells (Erythrocytes)
White Blood Cells (Leukocytes)
Platelets

7. Plasma
Plasma = fluid medium which transports the following around the body and accounts for 55% of blood volume:
Water: 92% of plasma
Proteins
Dissolved gasses: CO2 & O2
Nutrients: glucose, vitamins
Wastes
Hormones

9. Erythrocytes aka Red Blood Cells
Function:
Transport oxygen
No nucleus (more room for hemoglobin)
Contain hemoglobin:
Iron-containing protein with a high-affinity for oxygen
Carries oxygen from lungs  tissues
Has nothing to do with whether or not they are bound to oxygen. More like how superficial they are to the skin. Blue light passes through skin and illuminates the veins so we see them as blue. Optical illusion. Thread veins are illuminated by red light. Arteries would also be blue if they were closer to the surface, but they are deeper in the body since they carry higher pressure and need more protection.
2 million – 3 million Erythrocytes are produced each second! (developed in the bone marrow)

10. Hemoglobin
Protein which carries oxygen
Found inside red blood cells

12. Leukocytes aka White Blood Cells
Function:
<1% of total blood cells but will double when body is fighting infection
Have a nucleus
Several types of WBC’s, all of which serve a specific role in the immune system
Some WBC’s engulf invaders via phagocytosis  release enzymes that digest invader

13. 5 Types of WBC’s Granulocytes:
Neutrophil: Most abundant in body engulf and digest bacteria
Eosinophil: Found in lining of digestive and respiratory tracts. Attack and kill parasites and kill cancer cells
Basophil: Recognize pathogens and alert the immune system by secreting chemicals

14. 5 Types of WBC’s Agranulocytes
Lymphocytes: produce proteins called antibodies that incapacitate pathogens
Monocytes: help to destroy bacteria

15. Thrombocytes aka Platelets
Small cell fragment
No nucleus
Fragile
Rupture when they hit a sharp edge (i.e. torn blood vessel)  initiates blood clotting reaction (coagulation)

16. Blood Vessels

17. (gas exchange with body cells)
Summary of vessels
Capillaries
(gas exchange with body cells)
Arterioles
Venules
Arteries
(high pressure)
Veins
(low pressure)
Heart
Lungs
Arteries/arterioles carry blood away from heart
Veins/venules carry blood to the heart
oxygenated
deoxygenated

18. Arteries Carry blood away from the heart
Have thick walls - needed to withstand the high blood pressure
Walls contain smooth muscle and an elastic connective tissue
Pulse = change in diameter of arteries following heart contraction
Arteries branch into arterioles

19. Arterioles Smaller arteries
Walls contain muscles which can regulate the diameter of the arterioles
Vasoconstriction: diameter reduced, blood flow reduced
Vasodilation: diameter increased, blood flow increased
Arterioles branch into capillaries

20. Capillaries One cell thick (ideal for diffusion)
Site of gas/fluid exchange
Deliver O2/nutrients to body cells
Picks up CO2/wastes
Easily ruptured  bruising
Merge into venules

21. ALL Tissues are Surrounded by Capillaries

22. Venules Drain blood directly from capillaries
Thinner walls than arterioles
Lower pressure
Merge into veins

23. Veins Thinner walls than arteries, less muscle and connective tissue
Do not contract to help move blood back to the heart
Lower pressure
Arteries
Veins

24. Venules/Veins – Returning Blood to Heart
Solution
1. One-Way Valves
ONLY veins have them!
Prevent low pressure blood from flowing backwards
2. Contracting muscles
Example: the muscles of the leg help force blood through the valves in a step-wise fashion
stretching

26. Arteries Veins Arteries Veins Transport blood AWAY from the heart
Thick
Muscular
Do not have one-way valves
Transport blood TOWARDS the heart
Thin
Less muscle
Have one-way valves

27. Evolution of the Circulatory System
Unicellular and simple multicellular organisms do not need circulatory systems (use diffusion & osmosis)
Circulatory systems are an evolutionary adaptation to increase in size and complexity
The heart evolved from a simple
2-chambered structure to a
4-chambered structure

30. The Mammalian Circulatory System:

31. Heart Circuits
The pathway of vessels carrying blood to and from the lungs compromises the pulmonary circulatory system
The pathway of vessels carrying blood to and from the body compromises the systemic circulatory system

32. Systemic Systemic Pulmonary Capillary Beds of Head and Arms
Capillary Beds of Lungs
Pulmonary
Systemic
Capillary Beds of Trunk and Legs

33. Homework Read pages 482-488 Answer: Pg 486 # 7-12