1. Unifying Concepts of Animal Circulation
Every organism must exchange materials and energy with its environment.
Most animals are too large and complex for exchange by diffusion

2. Open and Closed Circulatory Systems
All but the simplest animals have a circulatory system with 3 mains parts:
A central pump
A vascular system (a set of tubular blood vessels)
Circulating fluid

3. Many invertebrates, have an open circulatory system
Circulating fluid is pumped through the open- ended vessels and flows out among cells
Many vertebrates, have a closed circulatory system
Blood is confined to vessels and is distinct from the interstital fluid
One or more hearts pump blood into large vessels that branch into smaller ones coursing through organs

4. The Human Cardiovascular System
Your circulatory system is organized into a double circulation system, where there are two routes for blood flow
These two routes are the pulmonary circuit and systematic circuit.
Pulmonary Circuit
Carries blood to and from the heart and lungs
Systematic Circuit
Carries blood to and from the heart and the rest of the body

6. The Heart The main base of the cardiovascular system is the Heart.
The heart will relax and contract in a cycle called the Cardiac cycle.
When the heart relaxes it fills with blood. This phase is known as diastole.
When the heart contracts it pumps blood. This phase is known as systole.
This cycle is measured as your heart rate. The average heart rate is from 60 to 80 beats per minute. However, a heart murmur where one of your heart valves are defective can occur.

7. The Hearts tempo is set by a sinotrial node or pacemaker.
The impulses that the pacemaker creates can be read and recorded by an EKG (electrocardiogram). With an EKG, your hearts health can be known.

9. Blood Flow Through Arteries
The force that blood exerts against the walls of your blood vessels is called blood pressure
The main force driving blood from the heart through arteries and arterioles to capillary beds
When ventricles contract, blood is forced into the arteries faster than it can flow into the arterioles
A pulse is the rhythmic stretching of the arteries caused by the pressure of blood forced into the arteries during systole

10. Hypertension, or high blood pressure, is persistent systolic blood pressure higher than 140 and/or diastolic blood pressure higher than 90.

11. Blood Flow Through Capillary Beds
About 5- 10% of your capillaries have a steady flow of blood running through them at any given time
These include capillaries in the brain, heart, kidneys, and liver, which are usually filled to capacity with blood
In many other sites, blood supply varies

12. Blood Flow Through Veins
After chemicals are exchanged between blood and body cells, blood returns to heart via veins
From capillaries blood moves into smaller venules, the into larger veins, then to venae cavae

14. Blood
The circulatory system has about 5 liters of blood. About half of this is plasma
Plasma is about 90% water and the leftover 10% are various other molecules.

15. Red Blood Cells
Red Blood cells are the most abundant type of cell in your body.
They are also referred to as erythrocytes.
Each blood cells consists of an iron containing protein, hemoglobin.
Hemoglobin enables the transportation of oxygen.
A low amount of red blood cells can result in anemia which causes extreme tiredness due to low oxygen levels.

16. White Blood Cells and Defense
As a group, leukocytes fight against infections and cancer
White blood cells lack hemoglobin, yet contain nuclei and a full complement of other organelles
White blood cells’ numbers increase when combating and infection

17. Platelets and Blood Clotting
Platelets (or thrombocytes) are bits of cytoplasm pinched off from larger cells in the bone marrow
When the epithelial lining of a blood vessel is damaged, clotting begins
Immediately platelets adhere to the damaged tissue and seals minor breaks
Platelets releases a clotting factor, fibrin, which, in dense networks, create patches on the skin known as scabs

18. A thrombus is a blood clot that forms in the absence of an injury
An embolus is a thrombus that has dislodged itself from the point of origin, and has moved throughout the body in blood
If an embolus lodges in an artery of the heart and is large enough to block it, a heart attack occurs
If an embolus lodges in the head, a stroke (the death of brain tissue) occurs

19. Leukemia Leukemia is cancer of the white blood cells, or leukocytes
A person with leukemia will have a far higher amount of defective white blood cells
These extra cells will crowd bone marrow and can lead to impaired clotting and anemia

20. Cardiovascular Disease
Cardiovascular disease is a set of diseases that affects the heart and blood vessels
A heart attack occurs when the coronary arteries that supply oxygen to cardiac muscle cells becomes blocked
The heart muscle cells the arteries feed will die form the lack of oxygen
This can lead to permanent damage to the heart muscle cells

21. Cardiovascular Disease
Atherosclerosis is a chronic cardiovascular disease which gradually impairs the arteries of most heart attack victims
During the course of the disease, cholesterol (among other substances) accumulates into plaque buildups that form on artery walls
This narrows the path through which blood flows, which more easily forms blood clots
Results of this include occasional chest pains known as angina

22. Unifying Concepts if Animal Respiration
The respiratory system consists of several organs that facilitate gas exchange
It requires close cooperation between the circulatory and respiratory systems

23. The Three Phases of Gas Exchange
Gas exchange in humans has three main steps:
Breathing- oxygen diffuses into blood vessels through the cells that line the lungs, while carbon dioxide passes from blood into the lungs to be exhaled
Oxygen transports to the rest of the body via the circulatory system
Cells take up oxygen from the body and release carbon dioxide into the blood. The oxygen is used to obtain energy, while carbon dioxide is transported back to the lungs to be released by the body

24. The Structure and Function of the Human Respiratory System

25. Taking a Breath
Negative pressure breathing- the air pressure in the lungs drops to below the air pressure of the atmosphere
This causes air to rush down to the lower-pressure region, which fills the lungs
The human brain’s control centers regulate our breathing
While we are at rest, signals are sent to the diaphragm and rib muscles to breathe at a steady rate
While we are active, the control centers increase or decrease the breathing rate depending on the amount of carbon dioxide in the blood