lecture 14 ppt

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Thought Question: What are the functions of your circulatory system?

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Lecture 14 Outline (Ch. 42) I.

Circulatory Systems

II.

Human Heart

III. Blood IV. Blood Vessels V.

Cardiovascular disorders

VI. Lymph VII. Gas Exchange (Bulk Flow & Diffusion) VIII. Gas Transport IX. Breathing X.

Respiratory problems & Smoking

XI. Lecture Concepts

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Circulation Overview Circulation carries energy, dissolved gasses, wastes

• •

Connects individual cells in distant parts of body Requirements – Blood – fluid for transport – Blood vessels – channels for transport – Heart – pump for circulation 4

Circulation Overview Circulatory systems are open or closed • •

Open- bathes organs in a hemocoel Closed- direct vessel connections to organs Heart

Hemolymph in sinuses surrounding organs

Pores

Heart

Blood Interstitial fluid

Small branch vessels In each organ

Dorsal vessel (main heart)

Tubular heart (a) An open circulatory system

Auxiliary hearts

Ventral vessels

(b) A closed circulatory system

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Circulation Overview Vertebrates have a closed circulatory system •

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More efficient – Blood is 5 – 10% of body volume – Blood flow is more rapid – Blood pressure is higher Multifunctional – Transport dissolved gasses – Distribute nutrients – Transport waste – Distribute hormones – Thermoregulation – Circulate immunodefenses

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The Vertebrate Heart

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Set of muscular chambers

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Atria collect blood Ventricles send blood through body

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The heart has evolved 7

Heart 4-chambered heart: A closer look

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2 pumps

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Right: deoxygenated blood Left: oxygenated blood

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Heart •

Right atrium receives deO2 blood from veins – Superior vena cava

– Inferior vena cava

Right ventricle pumps deO2 blood to lungs through pulmonary arteries Pumps into right ventricle 9

Heart •

Oxygenated blood returns to left atrium from lungs via pulmonary veins

Oxygenated blood pumped to body through aorta

Pumps into left ventricle 10

Heart Cardiac muscle contracts •

Present only in the heart

Cells linked by intercalated discs Prevents strong contractions from tearing muscle Allows rapid spread of electrical signal for simultaneous regional contraction

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Heart The Cardiac Cycle •

Coordinated contractions of atria & ventricles

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Heart The Cardiac Cycle & Blood Pressure •

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Systolic – Ventricular contractions (higher pressure) Diastolic – Period between contractions (lower pressure)

Normal blood pressure ~120/80 13

Heart Keeping blood moving • •

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Heart valves maintain oneway flow Atrioventricular valves – Between atria & ventricles Semilunar valves – Between ventricles & arteries

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Heart Keeping blood moving • •

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Pacemaker cells initiate and coordinate contractions Sinoatrial (SA) node – Primary pacemaker – Stimulates atrial contractions Atrioventricular (AV) node – Slows impulse received from SA node – Delays ventricular contraction until after atrial contractions have filled them with blood 15

Blood Plasma

• •

Primarily water Dissolved proteins and electrolytes

Blood

• •

Plasma fluid Cells – Red blood cells – transport – White blood cells – defense – Platelets – clotting

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Blood Red blood cells: Erythrocytes • • •

Most abundant blood cells (over 99%) Transport O2 and CO2 Iron-based hemoglobin protein binds to O2 and transports from areas of high concentration to low concentration

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Blood Erythrocytes are short-lived • • • •

Formed in bone marrow Lack nuclei (cannot divide or make proteins) Dead cells are removed by liver and spleen – Iron is recycled, although some is excreted Number of erythrocytes maintained by negative feedback

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Blood White blood cells: leukocytes • •

Less than 1% of blood cells Disease defense – – – – –

Consume foreign particles (macrophages) Produce antibodies (lymphocytes)

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Blood Platelets • •

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Cellular fragments aid blood clotting Ruptured cells and platelets work together to produce substances that plug damaged vessels Scabs are platelets embedded in web of fibrin proteins

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Blood is carried in vessels

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Artery

Vein

SEM

Valve

100 µm Basal lamina

Endothelium Smooth muscle Connective tissue

Endothelium Smooth muscle Capillary

Connective tissue

Artery

Vein

Capillary

15 µm

Red blood cell

Venule

LM

Arteriole

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Blood Vessels Arteries

Arterioles Arteries

• Carry blood away from heart • Thick-walled: Heart

Capillaries

• Smooth muscle/elastic fibers • Withstand high pressure

Veins

Venules 23

Blood Vessels Arteries

Arterioles Arterioles

• Control distribution of blood flow • Smooth muscle expands / contracts • Under hormone / NS control Capillaries Heart

Veins

Venules 24

Blood Vessels • • • •

Arterioles Contract walls: redirects blood to heart and muscles when needed (stress, exercise, cold) Relax walls: brings more blood to skin capillaries to dissipate excess heat Precapillary sphincters control blood flow to capillaries

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Blood Vessels Arteries

Arterioles Capillaries

• Nutrients/waste exchanged with cells: • Vessel wall one-cell thick • Blood flow very slow Capillaries Heart

• Materials exit/enter via diffusion

Veins

Venules 26

Blood Vessels

Capillaries connect & exchange • •

Tiny vessels Connect arterioles and venules

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Interstitial fluid leaks from plasma in capillaries and provides cells with means of exchange

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Blood Vessels Arteries

Arterioles

Venules & Veins • Carry blood towards the heart Heart

Capillaries

• Thin-walled; large diameter • One-way to prevent backflow

Veins

Venules 28

Blood Vessels Skeletal Muscle Pump:

Vein Valve:

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Blood Vessels Varicose veins occur if the vein valves become inefficient

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Blood Vessels Cardiovascular Disorders: • Leading cause of death in the United States 1) Hypertension = High blood pressure •  Resistance in vessels =  work for heart 2) Atherosclerosis = Deposits (plaques) collect in vessels Connective tissue

Smooth muscle

Endothelium

Plaque

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(a) Normal artery

50 µm (b) Partly clogged artery

250 µm

Lymph The lymphatic system • • •

Coordinates with circulatory system Includes: lymph nodes, vessels, and glands – Tonsils contain large numbers of lymphocytes – Thymus matures white blood cells – Spleen filters blood 32

Lymph Elephantiasis Condition caused by parasitic worm infection of the lymphatic system.

Symptoms most common in legs and genitals

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Lymph The lymphatic system •

Returns fluid to bloodstream –

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Lymph capillaries reabsorb interstitial fluid

Move fats to bloodstream from small intestine Bodily defense –

Contain masses of white blood cells in nodes

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Lymph Lymphatic vessels •

Narrow, thinwalled

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Cellular openings act as one-way valves

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Dead-end in tissues, collect materials flow back to larger blood vessels 35

Thought Question: If you are an athlete who trains at high elevations, what happens if you compete at a lower elevation?

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Overview

Living things process energy • They need oxygen for this - how do they get it?

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Overview Cellular respiration uses O2 and produces CO2 •

C6H12O6 + O2  CO2 + H2O + ATP energy

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Breathing – respiration supports this process by exchanging gasses

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Gas Exchange Systems Exchanging gasses •

Moist surface –

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Gasses dissolve in water to move in/out of cells

Thin Large surface area

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Gas Exchange Systems Who needs a respiratory system?

•I don’t! • • •

Moist environment Small (or thin) Low energy demand

•I do! • • •

Dryer environment Large or thick-bodied High energy demand

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Gas Exchange Systems Respiratory systems enable gas exchange •

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Bulk flow – Fluids move in bulk – Air/water move to respiratory surface – Blood moves through vessels Diffusion – Individual molecules move down concentration gradients – Gas exchange across respiratory surface – Gas exchange in tissues

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Gas Exchange Systems Gills • •

Aquatic gas exchange Delicate folded membranes

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Gas Exchange Systems Gills facilitate gas exchange in aquatic environments (e.g. fish):

• Elaborately folded ( surface area) • Contain capillary beds • Gill size inversely related to [O2] • Large gills = low [O2] 43

Gas Exchange Systems Fish Efficiency •

Dissolved O2 is < 1% of water (21% of air)

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Countercurrent exchange increases efficiency

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Gas Exchange Systems Terrestrial respiration •

Internal – Stay moist & supported

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Insects have tracheae – Air enters/exits through spiracles – Branching channels (trachioles) allow gas exchange with cells 45

Gas Exchange Systems Vertebrate respiration •

Terrestrial use of lungs –

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Evolved from accessory respiratory organs of freshwater fish

Amphibians are weird – – –

Remain tied to water Larval gills to adult lungs Moist skin transfers gasses

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Gas Exchange Systems Reptiles & Mammals use lungs exclusively • •

Lack permeable skin Lungs are more efficient – Especially birds!

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Mammals Human Respiration • • •

Air enters through nose and mouth to pharynx Travels through larynx (voice box) Epiglottis directs travel

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Human Respiration On to the lungs • • • •

Trachea  Bronchi  Bronchioles  Alveoli

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Human Respiration Air is warmed & cleaned • •

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Dust & bacteria trapped by mucus Swept up and out by cilia

Microscopic chambers provide enormous surface area Surfactant keeps surface moist Association with capillaries – Diffusion of gasses 50

Lungs Diffusion •

Blood arrives from pulmonary artery

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Low in O2 – Higher concentration in air diffuses into blood High in CO2 – Higher concentration in blood diffuses into air

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Transport of gasses O2 Transport •

Binds to hemoglobin – Removes O2 from plasma solution – Increases concentration gradient; favors diffusion from air CO binds more tightly to hemoglobin than O2 Prevents O2 transport 52

Transport of gasses CO2 Transport • • •

Binds hemoglobin loosely Dissolved in plasma Combines with H20 to form bicarbonate (HCO3-) –

More CO2 = lower pH

The Bohr Effect: Hemoglobin binds more tightly to O2 when pH is increased and loosely when pH is decreased

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Breathing Mechanisms The diaphragm helps move air in and out •

Inhalation – Chest cavity expands – Draws air in

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Exhalation – Chest cavity shrinks – Forces air out

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Breathing Mechanisms Breathing is involuntary • •

Controlled by the respiratory center of the brain Adjusts breath rate and volume based on sensory input – Maintain a constant concentration of CO2

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Respiratory Problems Asthma • • • •

Smooth muscle in bronchioles is excitable and constricts or spasms Increased mucus production clogs passages Can lead to collapse Some genetic factors, linked to air quality

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Respiratory Problems Emphysema • •

Alveoli rupture or become brittle Reduces surface area available for gas exchange

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Labored and difficult breathing

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Usually linked with smoking

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Respiratory Problems Bronchitis & Pneumonia • •

Inflammations of respiratory passages & lungs Increase in mucus production, decrease in cilia

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Reduces air flow to alveoli

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Causes include bacteria, viruses, fungi, & parasites

Jim Henson, creator of the Muppets, died at age 53 from pneumonia

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Respiratory Problems Tuberculosis •

Bacteria attack and cause lesions on lung tissue

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Smoking Smoking is BAD •

Toxins in cigarette smoke cause and/or exacerbate all of these respiratory problems in addition with many others – including lung cancer

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200 different toxins! – Tar, carbon monoxide, formaldehyde

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No positive benefits associated with smoking & many documented negative health effects 60

Lecture 14 concepts - Describe functions of circulatory and respiratory systems. - List chambers of human heart – which receive blood, which pump blood? - Explain the pulmonary circuit – which blood has high / low oxygen? - List four parts of blood - describe the function of each part (liquid and cells). - Describe arteries, veins, arterioles, venules, & capillaries. - What drives blood through arteries? How are veins different? - What is cardiovascular disease? Give examples.

- Name the parts of the lymphatic system and its role/function.

- In one sentence describe cellular respiration - Explain bulk flow and diffusion for gas exchange - Chart the path that air takes into and out of the lungs - What does carbon monoxide do in the blood stream? - How does hemoglobin exchange carbon dioxide for oxygen? - What part of your body controls breathing? How do you pull in a breath? - List new vocabulary and unknown terms.

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