THE CIRCULATORY AND RESPIRATORY SYSTEMS

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CHAPTER 38

• THE CIRCULATORY AND RESPIRATORY SYSTEMS

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The Circulatory System

• The circulatory system contains the network of
  blood vessels that connects the organs and
  muscles of the body, the muscular heart that
  pumps the blood and the lymphatic vessels that
  collect excess fluid.
• The circulatory system
• transports food, oxygen, wastes
• transports hormones
• helps defend the body
• helps distribute body heat

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Components of Circulatory System

• There are four major components of the human
  circulatory system
• blood vessels - network of tubes that carry blood
• lymphatic vessels - recover fluid that leaks out
  of blood vessels
• blood - connective tissue of cells and fluid
• heart - pumps blood throughout body
• Blood clotting ?

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Blood Vessels

• There are three main vessels
• arteries - thick, muscular walls
• carry blood away from heart
• blood pulses
• veins -less muscular walls
• valves prevent back flow
• carry blood toward heart
• capillaries - link arteries and veins
• walls only one cell thick
• narrow diameter - RBC line up single file to pass
  ?
• where actual exchange of materials takes place

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Patterns of Circulation

• General circulation path of blood
• heart?arteries ?arterioles ?capillaries ?venules
  ?veins ?heart

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Patterns of Circulation

• Pulmonary circulation - pumping blood from heart
  to the lungs back to heart.
• Systemic circulation - blood is pumped from heart
  to the bodys tissues back to heart.
• Coronary circulation - supplies blood to the
  heart muscle itself.

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The Heart

• The Heart
• The central organ of the cardiovascular system
• A double pump
• upper chambers atria
• lower chambers ventricles
• Within the thoracic cavity
• Surrounded by a saclike membrane the pericardium
• Vertically divided into two sides by the septum

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Flow of Blood...

• Follow the journey of blood through the heart on
  page 881 in your text.
• Note that there are valves preventing the
  backflow of blood.

Tricuspid valve
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Control of the Heartbeat

• Contraction of the heart is initiated by a small
  cluster of cardiac muscle cells embedded in the
  right atrium.
• This pacemaker of the heart is called the
  sinoatrial node (SA node).
• These cells initiate their own electrical impulse
  and cause the atria to contract.
• After this initiation the impulse then travels to
  the AV node to contract the ventricles.

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Control

• A heartbeat has two phases
• Phase 1 systole when ventricles contract to
  allow blood to exit the heart (AV valves close)
• Phase 2 diastole when ventricles relax (SL
  valves close)
• The closing of these two heart valves results in
  the characteristic lup dup sound associated
  with the heartbeat.
• If ones of these valves fails to close properly,
  some blood may leak backward (heart murmur)

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Cardiovascular Functions

• Cardiovascular functions can be monitored
• pulse heart rate
• blood pressure is measured with a
  sphygmomanometer relaxation of heart
  diastolic contraction of heart systolic
  pressure (Normal 120/80)
• electrical impulses produced by the heart muscle
  is measured with an EKG

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Blood

• The blood has two main components
• plasma - liquid portion (60 by volume)
• 90 water 10 solutes such as proteins, glucose,
  salts
• cells cell fragments (40 by volume) three
  types
• red blood cells (RBC) - erythrocytes
• 5M/ml
• contain hemoglobin carry oxygen

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Blood continued

• Blood composition
• cells cell fragments (types 2 3)
• white blood cells (WBC) - leukocytes
• 8,000/ml (? during infection)
• five different kinds
• defend body against disease, invasion
• some produce antibodies others are phagocytes
• platelets - thrombocytes
• release fibrin to help blood clot

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Blood Types

• Blood type (A, B, AB, O) is determined by the
  type of antigen (AG) present on the surface of
  the RBC.
• An antigen is a protein (usually) that acts as a
  signal, enabling the body to recognize foreign
  substances.

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Blood Types...

• Antigens normally present in a body provoke no
  response.
• Foreign antigens prompt the body to produce
  antibodies (AB), which are proteins that help
  destroy bacteria, viruses, other foreign
  antigens.
• The danger of mixing bloods of different types
  comes from the antibodies present in the plasma
  which might cause clumping (agglutination) of
  blood cells when reacting with AG on the RBC.
• Another important AG found on RBC is Rh factor.
  Rh- mothers may create problems for their Rh
  fetuses if the moms produce anti-Rh AB.

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Cardiovascular Diseases

• Cardiovascular diseases
• high blood pressure (hypertension)
• heart attack
• atherosclerosis (build-up of plaque )
• arteriosclerosis ( loss of elasticity)
• stroke

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Lymphatic System

• Lymphatic System
• Since blood in the circulatory system is under
  pressure, some fluid leaks out of capillaries and
  bathes cells. To collect and recycle this fluid,
  the body utilizes the lymphatic system.
• The lymphatic system utilizes a series of vessels
  to collect this fluid called lymph.
• Lymph nodes filter foreign substances store
  lymphocytes (WBC that are specialized to fight
  disease).

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Lymphatic System

• Unlike the circulatory system that forms a
  complete circuit, the lymph vessels form a one
  way system that returns fluids collected in the
  tissues back to the blood stream.
• Instead of a heart, skeletal muscles help move
  lymph.

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The Respiratory System

• It is the function of the respiratory system
  exchange gases with the atmosphere and to
  transport these gases to and from the circulatory
  system.
• Remember that they body requires O2 and creates
  CO2 in the process of cellular respiration.
• There are two places where gas exchange takes
  place
• Between the lungs and blood vessels
• Between the blood vessels and the tissues.

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The Respiratory System

• Air is carried to the lungs by way of a branched
  system of tubes and air sacs.
• Path of air through respiratory system
• nostrils - air is warmed, moistened and filtered
• pharynx - upper throat
• larynx - voice box
• trachea - covered by epiglottis
• tube reinforced with cartilage divides into
  bronchi
• bronchi - divide into bronchioles
• bronchioles - enter lungs
• lungs with alveoli (air sacs)

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Alveoli

• The end of the air passageway are air sacs
  surrounded by capillaries.
• This is where gas exchange in the lungs takes
  place.
• The alveoli are designed to increase surface are
  for gas exchange.

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Gas Exchange- O2

• Oxygen molecules diffuse from the alveoli into
  the blood plasma where it is picked up by RBC,
  containing hemoglobin (Hb).
• Each subunit of Hb contains an atom of iron that
  bonds reversibly with oxygen (4 molecules/Hb)
• Oxygen is transported to tissues where the O2
  levels are lower ? O2 is released from Hb.

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Gas Exchange CO2

• At the same time, CO2 is entering the blood from
  tissues.
• CO2 is carried in the blood in one of three ways
• Most carbon dioxide (67) is transported to the
  lungs as bicarbonate ions dissolved in the plasma
  - ionizes to form a weak acid
• CO2 diffuses from blood into alveoli in the
  lungs.

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Regulation of Breathing

• The amount of O2 needed (and CO2 produced) by the
  body depends upon the activity of the cells.
• It is involuntary.
• Breathing rate is controlled by amount of CO2 in
  blood (not the amount of O2) which changes the pH
  of the blood.
• The respiratory control center of brain regulates
  breathing rate.

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Mechanism of Breathing

• Breathing is the result of pressure changes
  inside the thoracic cavity.
• During inhalation/inspiration, the diaphragm
  contracts, moves downward, the ribs move up and
  out causing an increase in the size of the cavity
  ? a decrease in pressure.
• This allows air to enter the lungs.
• During exhalation/expiration, the diaphragm and
  ribs return to original position, causing a
  decrease in size of cavity ? an increase in
  pressure.
• This forces air from the lungs.

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Respiratory Diseases

• Respiratory diseases
• asthma - bronchioles become constricted because
  of sensitivity to certain stimuli in the air
• emphysema - loss of elasticity of alveoli,
  reduction in efficiency of gas exchange making it
  difficult to breathe (linked to smoking)
• lung cancer - caused by uncontrollable division
  of lung cells (also linked to smoking)
• Carbon monoxide poisoning is the result of CO
  making an irreversible bond with Hb.

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Smoking

• 160,000 diagnosed cases of lung cancer every
  year in U.S.
• nicotine causes pleasurable sensation, but hard
  to quit addiction
• Causes emphysema, cancer, heart disease
  (constricts blood vessels)