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The Human Circulatory System

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Title: The Human Circulatory System


1
The Human Circulatory System
2
Introduction
  • Humans and other vertebrates have a closed
    circulatory system
  • This means that circulating blood is pumped
    through a system of vessels
  • This system consists of the heart (pump), series
    of blood vessels and the blood that flows through
    them.

3
The Truth About Your Heart
4
The Heart
  • Located near the center of your chest
  • Hollow structure
  • Composed almost entirely of muscle
  • About the size of your clenched fist

5
The Heart
  • Enclosed in a protective sac called the
    pericardium

6
The Heart
  • In the walls of the heart, two layers of tissue
    form a sandwich around a thick layer of muscle
    called the myocardium.
  • Contractions of the myocardium pump blood through
    the circulatory system.

7
The Heart
  • The heart contracts about 72 times per minute
  • Pumps about 70mL of blood with each contraction.

8
The Heart
  • The right and left sides of the heart are
    separated by a septum, or wall.
  • The septum prevents the mixing of oxygen rich and
    oxygen poor blood.

9
The Heart
  • On each side of the septum are two chambers.
  • The upper chamber (receives blood) is the atrium.
  • The lower chamber (pumps blood out of heart) is
    the ventricle.

10
The Heart
  • The heart has a total of 4 chambers
  • 2 atriums
  • 2 ventricles

11
Pathway of Blood
  • Deoxygenated blood passes from the right atrium
    into the right ventricle and then goes to the
    lungs.
  • From the lungs, blood moves back toward the heart
    into the left atrium to the left ventricle and
    then passes into the aorta to go to the rest of
    the body

12
Valves
  • As the heart contracts, blood flows into the
    ventricles and then out through the ventricles.
  • Flaps of connective tissue, called valves, are
    located between the atria and ventricles.
  • Blood moving keeps the valves open.
  • When the ventricles contract, the valves close
    which prevent blood from flowing back into the
    atria.

13
Valves
  • There are also valves that stop blood from
    re-entering the ventricles after the blood has
    left.
  • This system of valves keeps blood moving in one
    direction which increases the pumping efficiency
    of the heart.

14
Heart Beat
  • Heart muscles are composed of individual fibers
  • Each atrium and ventricle contracts as a unit.
  • Each contraction begins with a group of cardiac
    muscle cells in the right atrium known as the
    sinoatrial node (SA node)

15
Heart Beat
  • Because the SA node paces the heart it is known
    as the pacemaker.
  • The impulse spreads from the pacemaker to the
    rest of the atria.
  • From the atria, a signal is sent to the
    atrioventricular node and then to a bundle of
    fibers in the ventricle.
  • When the ventricle contracts, blood flows out.

16
Blood Vessels
  • As blood moves through the circulatory system it
    moves through 3 types of blood vessels
  • Arteries
  • Capillaries
  • Veins

17
Arteries
  • Large vessels
  • Carry blood from heart to tissues of body
  • Carry oxygen rich blood, with the exception of
    pulmonary arteries.
  • Thick walls-need to withstand pressure produced
    when heart pushes blood into them.

18
Capillaries
  • Smallest blood vessels
  • Walls are only one cell thick and very narrow.
  • Important for bringing nutrients and oxygen to
    tissues and absorbing CO2 and other waste
    products.

19
Veins
  • Once blood has passed through the capillary
    systems it must be returned to the heart.
  • Done by veins
  • Walls contains connective tissue and smooth
    muscle.
  • Largest veins contain one way valves that keep
    blood flowing toward heart.
  • Many found near skeletal muscles. When muscles
    contract, blood is forced through veins.

20
Blood Pressure
  • The heart produces pressure
  • The force of blood on the wall of the arteries is
    known as blood pressure.
  • Blood pressure decreases as the heart relaxes,
    but the rest of the circulatory system is still
    under pressure.

21
Blood Pressure
  • When blood pressure is taken, the cuff is wrapped
    around the upper portion of the arm and pumped
    with air until blood flow in the artery is
    blocked.
  • As the pressure in the cuff is relaxed, 2 numbers
    are recorded.
  • Systolic pressure- the first number taken, is the
    force felt in the arteries when the ventricles
    contract.
  • Diastolic pressure- the second number taken, is
    the force of the blood on the arteries when the
    ventricles relax.

22
Disorders of Circulatory System
  • Atherosclerosis
  • Fatty deposits (plaque) in walls of arteries
  • Deposits can obstruct flow of blood which can
    raise blood pressure
  • Increases risk of blood clots
  • If clot breaks free it can obstruct blood flow to
    tissues.

23
Disorders of Circulatory System
  • Heart Attack
  • Due to atherosclerosis, coronary arteries may
    become blocked (blood cant get to heart muscle)
  • Heart muscle begins to die due to lack of O2

24
Disorders of Circulatory System
  • Stroke
  • Blood clot may break free and block a vessel
    leading to the brain.
  • Brain cells are starved of oxygen and nutrients
  • Loss of function may occur
  • Can cause paralysis, loss of ability to speak or
    death.

25
Blood
  • Composed of plasma and blood cells
  • Types of Cells are
  • Red Blood Cells
  • White Blood Cells
  • Platelets

26
Blood
  • Plasma
  • Straw colored
  • 90 water
  • 10 dissolved gases, salts, nutrients, enzymes,
    hormones, wastes, and proteins.

27
Blood
  • Plasma proteins
  • 3 Types Albumins, globulins and fibrinogen.
  • Albumins and Globulins- transport substances such
    as fatty acids, hormones and vitamins.
  • Fibrinogen- Responsible for bloods ability to
    clot

28
Blood
  • Red Blood Cells
  • Most numerous type
  • Transport oxygen
  • Get color from hemoglobin
  • Disk shaped
  • Made in red bone marrow
  • Circulate for 120 days

29
Blood
  • White Blood Cells
  • Guard against infection, fight parasites, and
    attack bacteria
  • Number of WBCs increases when body is fighting
  • Lymphocytes produce antibodies which fight
    pathogens and remember them

30
Blood
  • Platelets
  • Aid the body in clotting
  • Small fragments
  • Stick to edges of broken blood cell and secrete
    clotting factor to help form clot.

31
Blood Clotting Problems
  • Hemophelia
  • Genetic disorder that disrupts clotting
  • People must be very careful to avoid injury
  • Can be treated by injecting extracts that contain
    the missing clotting factor.
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