The Circulatory System

1
The Circulatory System
2
The Circulatory System

• Also called the cardiovascular system
• Is made of the heart, blood, and blood vessels
• Allows blood to flow to all parts of your body
• Has 3 main jobs
• Carries needed substances to cells
• Oxygen and glucose
• Carries waste products away from cells
• Carbon dioxide
• Contains cells that fight disease

3
The Heart
4
The Heart

• A hollow muscular organ that pumps blood
  throughout the body
• About the size of your fist
• Located in the center of the chest, beneath the
  sternum and inside the ribcage
• Made of cardiac muscle
• Contracts over and over without tiring out

5
The Heart

• Acts as two pumps
• Right side pumps blood into the lungs where it
  picks up oxygen
• Left side pumps blood into the arteries where it
  is sent throughout the body
• The two sides are separated by a wall of tissue
  called the septum.

6
The Heart

• Each side has two chambers
• The upper chambers are called atria.
• The lower chambers are called ventricles.

7
The Atria

• The upper chambers of the heart
• Job is to receive blood that comes into the heart
• The right atrium has a group of cells called the
  pacemaker (sinoatrial node) that sends signals to
  make the heart muscle contract

8
Pacemaker

• Whenever someone has problems with an irregular
  heartbeat, doctors may give them an artificial
  pacemaker.
• This helps their heart maintain a normal rhythm.

9
Ventricles

• The lower chambers
• Job is to pump blood out of the heart
• Right ventricle pumps blood to the lungs
• Left ventricle pumps blood out of the heart and
  into the body

10
Valves

• The ventricles are separated from the atria by
  valves
• Flaps of tissue that prevents blood from flowing
  backward
• Also located between the ventricles and the large
  blood vessels that carry blood out of the heart

11
How the Heart Works

• Two phases
• Heart muscle relaxes and atria fill with blood
• Heart muscle contracts and blood pumps forward
• This closes the valves between the atria and the
  ventricles
• Creates the lub sound
• The valves between the ventricles and the blood
  vessels snap shut
• Creates the dup sound

12
Two Loops

• Overall pattern of blood flow in the body is like
  the figure eight.
• In the first loop, blood travels from the heart
  to the lungs and then back to the heart.
• In the second loop, blood is pumped from the
  heart throughout the body and then returns to the
  heart.
• Blood travels in only one direction.
• One drop of blood could make the journey through
  both loops in less than a minute.

13
The Path of Blood Flow

1. Vena cava is a large vein that carries
   oxygen-poor blood to the heart
2. The right atrium receives the oxygen-poor blood
   from the vena cava.
3. Blood leaves the right atrium through the
   tricuspid valve and enters the right ventricle
4. From the right ventricle the blood passes through
   the pulmonary valve and enters the pulmonary
   artery, which sends the blood to the lungs

14
The Path of Blood Flow

• 5. In the lungs, blood picks up oxygen it then
  passes through the pulmonary veins.
• 6. From the pulmonary veins, oxygen-rich blood
  enters into the left atrium.
• 7. From the left atrium, the blood then passes
  through the mitral valve and empties into the
  left ventricle.
• 8. The blood leaves the left atrium through the
  aortic valve, and enters the aorta.
• 9. The aorta sends oxygen-rich blood to all parts
  of the body.
• 10. Once the bodys cells receive the blood, they
  exchange carbon dioxide for oxygen.
• 11. The oxygen-poor blood makes its way to the
  vena cava, where it can start its journey again.

15
Pumping Heart Video
16
Blood Vessels

• There are three kinds of blood vessels
• Arteries
• Carry blood away from the heart
• Veins
• Carry blood to the heart
• Capillaries
• Exchange substances between the blood and body
  cells

17
Arteries

• Job is to carry blood away from the heart
• Each artery branches into smaller and smaller
  branches
• Smallest branches are called arterioles.
• Arterioles join to capillaries
• Aorta is the largest artery in the body
• Has many branches

18
Coronary Arteries

• The coronary arteries are the branches of the
  aorta that supply the heart muscle with blood
• Blockages of these arteries can lead to heart
  attacks

19
Structure of an Artery

• Have very thick walls made of three cell layers
• The innermost layer is smooth and is made of
  epithelial cells.
• Lets blood flow freely
• The middle layer is made of muscle tissue.
• Acts as a control gate, controlling how much
  blood enters the vessel
• The outer layer is made of flexible connective
  tissue
• Allows the arteries to withstand the force of the
  blood being pushed through them.
• Arteries are strong and flexible
• Able to withstand much pressure
• The pulse is caused by the alternating expansion
  and relaxation of the artery wall

20
Veins

• Veins carry blood to the heart.
• Veins branch into smaller and smaller branches.
• The smallest branches are called venules.
• Venules are attached to the capillaries.

21
Structure of the Veins

• Veins are made of three layers, but are thinner
  than arteries.
• Because the force of blood flow is not as strong
  when blood reaches the veins, the blood needs
  help moving.
• Contractions of skeletal muscles helps to push
  blood through the veins.
• Larger veins have valves in them to prevent blood
  from flowing backward.
• Breathing movements help to force blood to the
  heart.

22
Capillaries

• In the capillaries, materials are exchanged
  between the blood and the bodys cells.
• The capillaries form a web between the arteries
  and the veins.
• Capillary walls are made of epithelial tissue.
• Capillary walls are only one cell thick.
• Materials pass easily through them using the
  process of diffusion, molecules moving from areas
  of high to low concentration.

23
Blood
24
Blood

• Blood is made of four components, or parts
• Plasma, red blood cells (RBCs), white blood cells
  (WBCs), and platelets
• About 45 of the volume of blood is cells the
  rest is plasma

25
Plasma

• Most of the materials transported in the blood
  travel in the plasma.
• Plasma is the liquid part of blood.
• 90 of plasma is water
• 10 is dissolved materials, such as glucose,
  fats, vitamins, and minerals
• Many waste products are carried away by the plasma

26
Plasma

• Proteins give plasma its yellow color
• Three groups of plasma proteins
• Helps regulate amount of water in blood
• Helps fight disease
• Interacts with platelets to form blood clots.

27
Red Blood Cells(RBCs)

• RBCs take up oxygen in the lungs and deliver it
  to cells throughout your body
• Produced in the bone marrow (like other blood
  cells)
• Look like doughnuts that someone forgot to cut
  out the hole
• Because they are thin in the middle, they are
  able to bend and twist easily
• Allows them to squeeze into tiny capillaries

28
RBCs

• Made mostly of hemoglobin, an iron-containing
  protein that chemically binds to oxygen.
• Hemoglobin is also able to pick up some carbon
  dioxide, but most is carried by the plasma
• When hemoglobin and oxygen join together, the
  cell becomes bright red without oxygen, the cell
  is dark red
• Arteries have blood that is bright red
• Veins have blood that is dark red

29
RBCs

• Mature RBCs have no nuclei
• Without a nucleus, it cannot reproduce or repair
  itself
• Only are able to live 120 days
• Every second, about 2 million RBCs die
• Bone marrow makes new cells at the same rate

30
White Blood Cells(WBCs)

• Produced in the bone marrow
• WBCs are the bodys disease fighters.
• Some recognize disease causing organisms and
  alert the body that it has been invaded
• Others produce chemicals to fight the invaders
• Others surround and kill the invaders

31
WBCs

• There are fewer WBCs than RBCs.
• Larger than RBCs
• Several different types of WBCs
• WBCs have nuclei
• Can live for months or even years

32
Platelets

• Platelets are cell fragments that play an
  important role in forming blood clots

33
Forming Clots

• When a vessel is cut, platelets collect and stick
  around the cut.
• Platelets release a chemical that leads to the
  production of a protein called fibrin.
• Fibrin makes a net of fibers across the wound.
• This net traps blood cells.
• As more and more of the platelets and cells get
  caught in the fibrin net, a clot forms.
• A scab is a dried blood clot on the skins surface

34
Blood Types

• Four major blood types A, B, AB, O
• Types are determined by the proteins known as
  marker molecules that are on RBCs
• A has the A marker, B has the B marker, AB has
  both A and B, O has no markers on it

35
Blood Types

• Plasma has proteins that recognize cells with
  foreign markers and they make those cells clump
  together
• A has anti-B proteins
• B has anti-A proteins
• AB has no anti-proteins
• O has both anti-A and anti-B proteins

36
Why is Blood Type Important?

• Your blood type determines what type of blood you
  can safely receive in a blood transfusion.
• If you are A, you can receive A and O blood
• If you are B, you can receive B and O blood
• If you are AB, you can receive, A, B, AB, and O
• Universal recipients
• If you are O, you can only receive O blood
• Universal donors

37
Rh factor

• The Rh factor is another protein that is found in
  the blood.
• You are either Rh or Rh-
• Rh factor is named for the Rhesus monkey, which
  was the first organism recognized to have the Rh
  factor

38
(No Transcript)
39
The Lymphatic System

• As blood travels through the circulatory system,
  some of the fluid leaks out.
• The fluid moves through the walls of the
  capillaries and into the tissues.
• The fluid carries materials the cells in the
  tissues need.
• After bathing the cells, the fluid moves into the
  bodys drainage system, the lymphatic system.
• A network of vein-like vessels that returns the
  fluid to the bloodstream

40
Lymph

• Once inside the lymphatic system, the fluid is
  called lymph.
• Lymph is made of water and dissolved materials
  it also has some white blood cells in it.
• The lymphatic system has no pumps, so lymph moves
  very slowly.
• The lymphatic vessels connect to large veins in
  the chest.
• Lymph empties into these veins and the fluid
  becomes part of the plasma again.

41
Lymph Nodes

• Lymph nodes are pieces of tissue that filter
  lymph, trapping bacteria and other
  disease-causing microorganisms in the fluid.

42
Lymph Nodes

• When the body is fighting infection, the lymph
  nodes enlarge.
• Sometimes referred to as swollen glands.

43
Cardiovascular Diseases

• Cardiovascular disease is the leading cause of
  death in the U.S. today.

44
Atherosclerosis

• Atherosclerosis is a condition in which an artery
  wall thickens as a result of the buildup of fatty
  materials such as cholesterol.
• This reduces the flow of blood in the affected
  artery.

45
Atherosclerosis

• When atherosclerosis develops in the coronary
  arteries, the heart muscle receives less blood
  (less oxygen), which can lead to a heart attack.
• Heart attacks occur when the blood flow to part
  of the heart muscle is blocked.
• Cells die in the part of the heart that does not
  receive blood and oxygen. This permanently
  damages the heart

46
Treating Atherosclerosis

• Low-fat diet and exercise for mild cases.
• Some medications can be prescribed.
• Severe cases may lead to angioplasty, where a
  small balloon is inserted into the blocked artery
  to help open it up.
• When arteries are completely blocked, a bypass
  operation may be performed.
• In a bypass, a vein from the leg is used to
  create an alternate path for blood to flow into
  the heart muscle.

47
Hypertension

• Hypertension is high blood pressure.
• A person will have hypertension if their blood
  pressure is consistently greater than 140/90.
• High blood pressure makes the heart work harder
  to pump blood through the body, possibly damaging
  the walls of the blood vessel.
• Because most people have no obvious signs of the
  disease it is called the silent killer.

48
Treating High Blood Pressure

• Closely related to atherosclerosis.
• As arteries narrow, the blood pressure increases.
• Diet and exercise help
• Limit intake of salt
• Sometimes given medications that lower blood
  pressure

49
Measuring Blood Pressure

• Blood pressure is measured by a device called a
  sphygmomanometer
• The first number in a blood pressure reading is
  the measurement of the blood pressure when the
  ventricles contract.
• The second number, which is lower, is the blood
  pressure when the ventricles relax.
• The blood pressure is given as a fraction with
  the contraction pressure, or systolic, over the
  relaxation pressure, or diastolic.
• A healthy blood pressure is 120/80 or lower.