OBJECTIVES Circulation in Animals

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OBJECTIVES   -Circulation in Animals

• Describe the need for circulatory and respiratory
  systems due to increasing animal body size
• Distinguish between open and closed circulatory
  systems. List the three basic components common
  to both systems.
• List the structural components of a vertebrate
  circulatory system and relate their structure to
  their functions
• Describe the general relationship between
  metabolic rates and the structure of the
  vertebrate circulatory system
• Using diagrams, compare and contrast the
  circulatory systems of fish, amphibians, non-bird
  reptiles, and mammals or birds
• Distinguish between pulmonary and systemic
  circuits and explain the functions of each
• Explain the advantage of double circulation over
  a single circuit

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• Define a cardiac cycle, distinguish between
  systole and diastole, and explain what causes the
  first and second heart sounds.
• Define cardiac output and describe two factors
  that influence it.
• List the four heart valves, describe their
  location, and explain their functions.
• Define heart murmur and explain its cause.
• Define sinoatrial (SA) node and describe its
  location in the heart
• Distinguish between a myogenic heart and a
  neurogenic heart
• Describe the origin and pathway of the action
  potential (cardiac impulse) in the normal human
  heart.
• Explain how the pace of the SA node can be
  modulated by nerves, hormones, body temperature,
  and exercise.
• Define blood pressure and describe how it is
  measured.
• Explain how peripheral resistance and cardiac
  output affect blood pressure

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• Relate the structures of capillaries, arteries,
  and veins to their functions.
• Explain why blood flow through capillaries is
  substantially slower than it is through arteries
  and veins.
• Explain how blood returns to the heart even
  though it must sometimes travel from the lower
  extremities against gravity.
• Explain how blood flow through capillary beds is
  regulated.
• Explain how osmotic pressure and hydrostatic
  pressure regulate the exchange of fluid and
  solutes across capillaries.
• Describe the composition of lymph and explain how
  the lymphatic system helps the normal functioning
  of the circulatory system. Explain the role of
  lymph nodes in body defense.
• Describe the composition and functions of plasma.
• Relate the structure of erythrocytes to their
  function.
• List the five main types of white blood cells and
  characterize their functions.
• Describe the structure of platelets.
• Outline the formation of erythrocytes from their
  origin from stem cells in the red marrow of bones
  to their destruction by phagocytic cells.
• Describe the hormonal control of erythrocyte
  production.
• Outline the sequence of events that occurs during
  blood clotting and explain what prevents
  spontaneous clotting in the absence of injury.
• Distinguish between a heart attack and a stroke.
• Distinguish between low-density lipoproteins
  (LDLs) and high-density lipoproteins (HDLs).
• List the factors that have been correlated with
  an increased risk of cardiovascular disease.   

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Gas Exchange in Animals

• Define gas exchange and distinguish between a
  respiratory medium and a respiratory surface
• Describe the general requirements for a
  respiratory surface and list a variety of
  respiratory organs that meet these requirements.
• Describe respiratory adaptations of aquatic
  animals.
• Describe the advantages and disadvantages of
  water as a respiratory medium.
• Describe countercurrent exchange and explain why
  it is more efficient than the concurrent flow of
  water and blood.
• Describe the advantages and disadvantages of air
  as a respiratory medium and explain how insect
  tracheal systems are adapted for efficient gas
  exchange in a terrestrial environment.
• For the human respiratory system, describe the
  movement of air through air passageways to the
  alveolus, listing the structures that air must
  pass through on its journey.
• Compare positive and negative pressure breathing.
  Explain how respiratory movements in humans
  ventilate the lungs.
• Distinguish between tidal volume, vital capacity,
  and residual volume.
• Explain how the respiratory systems of birds and
  mammals differ.
• Explain how breathing is controlled in humans.
• Define partial pressure and explain how it
  influences diffusion across respiratory surfaces.
• Describe the adaptive advantage of respiratory
  pigments in circulatory systems. Distinguish
  between hemocyanin and hemoglobin as respiratory
  pigments.
• Draw the Hb-oxygen dissociation curve, explain
  the significance of its shape, and explain how
  the affinity of hemoglobin for oxygen changes
  with oxygen concentration.
• Describe how carbon dioxide is picked up at the
  tissues and deposited in the lungs.
• Describe the respiratory adaptations of the
  pronghorn that give it great speed and endurance.
• Describe respiratory adaptations of diving
  mammals and the role of myoglobin.

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CHAPTER 42CIRCULATION AND GAS EXCHANGE
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TRANSPORT SYSTEMS

• Circulatory Systems Reduce Distances Substances
  Must Diffuse diffusion too slow for most animals

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Circulatory Systems Connect Aqueous Environment
of Cell with Organs Specialized for Exchange

• Oxygen diffuses from air in lungs across
  epithelium, into blood
• Oxygenated blood transported to all body parts
• Oxygen diffuses from blood and through plasma
  membrane
• Carbon dioxide moves in opposite direction

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Circulatory Systems Maintain Homeostasis

• Blood passes through liver and kidneys which
  regulate nutrient and waste content

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INVERTEBRATES

• Gastrovascular Cavities
• Cnidarians do not require specialized internal
  transport body wall 2 cells thick
• Water inside gastrovascular cavity is continuous
  with surrounding water
• Cavity functions both in digestion and
  distribution of nutrients
• Nutrients have a short distance to diffuse to
  outer cell layer

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Open and Closed Circulatory Systems

• Open circulatory system (arthropods, mollusks)
  hemolymph bathes internal organs in sinuses (Fig
  38.2a 4th ed)
• Hemolymph blood and interstitial fluid
• Circulation contractions of heart and body
  movements
• Relaxation blood enters through ostia
• Chemical exchange btw. hemolymph and cells in
  sinuses

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Closed circulatory system (annelids, squids,
octopuses, vertebrates) blood confined to
vessels and distinct interstitial fluid present

• Heart pumps blood into large vessels
• Major vessels branch into smaller vessels which
  supply organs (Fig 38.2b)
• Blood exchanges materials with interstitial fluid

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VERTEBRATES

• Cardiovascular System heart, blood vessels,
  blood
• Heart ? arteries ? arterioles ? capillaries ?
  venules ? veins ? heart

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Fish 2 chambered heart, 1 atrium, 1 ventricle

• Ventricle ? gill capillaries (gas exchange) ?
  arteries ? organ capillary beds ? veins ? atrium
  ? atrium ? ventricle
• Blood flow through two capillary beds drops blood
  pressure
• Blood flow aided by swimming

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Amphibians 3 chambered heart, 2 atria, 1
ventricle

• Double Circulation pulmonary, systemic
• Ventricle ? lungs/skin (gas exchange) ? left
  atrium ? ventricle ? all other organs ? right
  atrium
• Increased blood pressure for system circulation
• Some mixing of oxygenated and deoxygenated blood
  ridge in ventricle diverts mostly oxygenated
  blood to systemic circulation

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Reptiles (excluding crocodilians) 3 chambered
hearts with partially divided ventricle

• Reduces mixing of oxygenated and deoxygenated
  blood

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Birds, Mammals, Crocodilians 4 chambered heart
with 2 atria and 2 ventricles

• Prevents mixing of blood
• Increased oxygen delivery efficiency

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THE RHYTHMIC PUMP

• The Heart Form and Function

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Human Heart

• Located beneath sternum
• Cone-shaped, fist sized
• Surrounded by sac with a 2-layered wall
• Mostly muscle tissue
• Atria thin-walled collection chambers
• Ventricles thick-walled, powerful pumps

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Heart chambers alternatively contract and relax
in rhythmic cycle

• Cardiac cycle
• Systole contraction, pump
• Diastole relaxation, fill

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Valves prevent backflow

• Connective tissue
• Atrioventricular atrium/ventricle
• Semilunar valves ventricles/arteries
• Heart murmur

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Heart Rate number of beats per minute

• Pulse
• Average resting rate 60 beats/minute
• Inverse relationship between animal body size and
  pulse

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Cardiac output volume per minute

• Stroke volume volume per pump

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Control of Heart Myogenic (self-excitable)
tempo controlled by sinoatrial (SA) node

• Right atrium
• Specialized muscle with characteristics of muscle
  and nerve tissue
• Atria contract in unison
• Excitation causes atrioventricular (AV) node to
  contract
• Electrocardiogram (EKG) detects electrical
  currents
• Rate influenced by antagonistic nerves, hormones,
  temperature, exercise

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Blood Vessel Structure

• Arteries/veins have 3 layers outer elastic
  connective, middle smooth muscle, inner
  epithelium (simple squamous epithelium)
• Middle/outer layers thicker in arteries than in
  veins
• Capillaries only endothelium

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More blood flows through large vessels than in
small vessels due to total smaller diameter in
large vessels
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Blood Pressure Hydrostatic force blood exerts
against vessel wall

• Pressure greatest in arteries during systole
• Peripheral resistance (arterioles)
• Determined by cardiac output and peripheral
  resistance
• Stress constricts
• Veins pressure near zero skeletal muscles,
  breathing, valves

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Blood Pressure and Flow through the arteries,
capillaries, to veins
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Blood Flow Through Capillary Beds

• 5-10 of capillaries carry oxygen at one time
• Full load in brain, heart, kidneys, liver
• Distribution controlled by nerves hormones
• Arteriole contraction/relaxation
• Precapillary sphincters
• Diversion
• To digestive tract after meal
• To skeletal muscle - exercise

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Capillary Exchange

• Exchange between blood and interstitial fluid
• Diffusion, endo/exocytosis, bulk flow
• Fluid leaves near arteriole and 85 reenters near
  venule
• 15 returned through lymphatic system

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Lymphatic System

• Lymph similar to interstitial fluid
• Lymph diffuses into lymph capillaries
• Valves and contractions
• Lymph nodes swellings along system that filter
  lymph and attack viruses and bacteria
• Lymph capillaries absorb fats from villi

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BLOOD CONNECTIVE TISSUE CELLS AND PLASMA

• Plasma 45 of Blood, 90 water
• Electrolytes dissolved ions osmotic balance,
  buffer
• Proteins escort lipids, immunoglobulins,
  clotting factors
• Serum clotting factors removed
• Contains nutrients, metabolic wastes, respiratory
  gases, hormones

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Cellular Elements

• Erythrocytes Red Blood Cells biconcave discs
• Most numerous of cells
• Lack nuclei, anaerobic respiration
• Contains hemoglobin, reversible bind oxygen to
  iron
• Erythropoietin from kidneys

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• Leukocytes White Blood Cells defense and
  immunity
• Basophils, eosinophils, neutrophils, lymphocytes,
  monocytes
• Interstitial fluid, lymph nodes
• Platelets cellular fragments, blood clotting

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Cell types in a blood smear
Platelets
Eosinophils
Neutrophils
Monocytes
Lymphocytes
Basophils
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• Multipotent stem cells give rise to all blood
  cells in bone marrow (ribs, vertebrae,
  breastbone, pelvis)

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• Blood Clotting Platelets clump, release
  clotting factors, fibrinogen ? fibrin

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CARDIOVASCULAR DISEASES

• Leading Cause of Death in the United States
• Heart Attack death of cardiac muscle resulting
  from blockage of coronary arteries
• Stroke death of nervous tissue in brain
  resulting from blockage of arteries in brain
• Thrombus blood clot that blocks a vessel
• Embolus moving clot

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CARDIOVASCULAR DISEASES Cont.

• Atherosclerosis plaques develop on inner walls
  of arteries and narrow vessels. Decrease blood
  flow, increase risk of clot formation
• Arteriosclerosis calcium deposits
• Angina pectoris chest pains, insufficient
  oxygen
• Hypertension high blood pressure, promotes
  atherosclerosis
• Smoking, diet, LDLs (Low Density Lipoprotein),
  HDL (High Density Lipoprotein)

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GAS EXCHANGE

• Movement of oxygen and carbon dioxide between
  animal and the environment
• Respiratory Medium Source of oxygen air or
  water

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Respiratory Surface Where exchange occurs

• Moist gases dissolved in water
• Large
• Protozoa Entire surface area
• Sponges, cnidarians, flatworms each body cell
  in contact with outside environment
• Earthworms, some amphibians use moist skin
• Specialized organs

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GILLS

• Vary in shape and location among organisms
• Ventilation Any method of increasing flow of
  respiratory medium over respiratory surface
• Water has low oxygen content much energy spent
  on ventilation
• Countercurrent exchange blood flows opposite to
  direction in which water passes maintains
  concentration gradient

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TRACHEAE INSECTS

• Advantages of air over water
• High oxygen content
• Gases diffuse faster in air
• Ventilation less important
• Air desiccation problem solved through internal
  respiratory surfaces

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Trachea tiny air tubes in insect body

• Spiracles
• Contact with almost all cells
• Diffusion or ventilation
• Circulatory systems dont transport gases

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LUNGS

• Form and Function of Mammalian Respiratory
  Systems
• Thoracic cavity 2-layered sac
• Nostrils warm, moisten, filter
• Pharynx, glottis, larynx, trachea, bronchi,
  bronchioles, alveoli
• Oxygen dissolves in moist film covering
  epithelium and diffuses to capillaries carbon
  dioxide moves in opposite direction

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Ventilation Breathing

• Frogs positive pressure breathing
• Mammals negative pressure breathing
• Diaphragm, ribs
• Contract, expand
• Relax, compress
• Tidal volume normal breath volume
• Vital capacity maximum air volume
• Residual volume amount that remains in lungs
• Birds air sacs in abdomen, neck
• Air sacs do not exchange gases bellows
• Parabronchi tiny channels one direction

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• Control of Breathing
• Medulla oblongata, pons negative feedback,
  sense carbon dioxide levels

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• Loading/Unloading Oxygen
• Gases diffuse from higher partial pressure to
  lower partial pressure

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Respiratory Pigments and Oxygen Transport

• Hemocyanin (arthropods, mollusks) blue due to
  copper, not confined to cells
• Hemoglobin vertebrates
• 4 subunits heme group, Fe
• Cooperativity (Fig 38.26)
• Bohr shift (Fig 38.26b)

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Carbon Dioxide Transport

• Transported in three forms
• Dissolved carbon dioxide in plasma (7)
• Bound to amino groups of hemoglobin (23)
• As bicarbonate ions in blood (70)
• Formation of bicarbonate produces H ions and
  attach to hemoglobin and results in only slight
  pH change

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Adaptations of Diving Mammals

• Store large amounts of oxygen in blood
• Higher myoglobin concentration in muscles
• Higher blood volume