Internal Systems and Regulation

Internal Systems and Regulation Transportation and Circulation

What does the transport system do? • Nutrients travel to and wastes away from all cells • Pathway for disease fighting agents and hormones • Control of body temperature – homeostasis • Vascular system = system of fluid tissue that plays a role in transporting nutrients to cells in the body • Circulatory system = system in which the progress of fluid is controlled by muscle movements • Cardiovascular system = circulatory system in which the vascular fluid is moved around by a pump

Internal Transport • Unicellular – no need for organized transport • One cell so diffusion allows movement of substances in and out (eg. Amoeba) • Cytoplasm streaming is utilitized to move substances once inside the cell • Multicellular – some do not require organized transport • Cnidaria (eg. hydra and jellyfish) fluid taken in through the mouth enters a body cavity that extends through the body of the organism. • Cells are no more then a few layers thick at any point so diffusion is key once again.

Internal Transport • Specialization – required for most multicellular organisms • Open Transportation Systems (p. 243, fig. 4) • Blood does not always stay contained within blood vessels • Fluid is moved around the chambers (sinuses) of arthropods by coordinated movements of the body muscles • Circulation occurs from the aorta to the sinuses relatively slowly – transport is not rapid • Remember that insects have a tracheal respiratory system which is separate from this transport system

Internal Transport • Closed Transportation System (p.243, fig. 5) • Blood does not bathe the cells directly, but rather is pumped around the body using a network of vessels • Fluid circulates only in one direction, passing through the gas exchange system in the cycle • Factors which affect the efficiency of transport include: • Composition of blood • Path of circulation • Speed of blood flow

Specialized Internal Transport • Fish • Blood travels through the heart only once during each complete circuit around the body • Blood travels out of heart via the ventral artery to the capillaries in the gills. From there the blood travels to the dorsal artery where the body receives oxygenated blood • Advantage = all blood traveling from the heart is oxygenated in the gills • Disadvantage = blood pressure created by the heart is lost in the capillaries in the gills (they are elastic)

Specialized Internal Transport • Amphibians – frogs, toads, salamanders • As fish have two chambers, animals in class Amphibia have three chambered hearts. • Blood travels from heart to lungs, then back to heart where it is pumped again into the arteries to the body • Blood that returns from the lungs and blood that returns from the body mixes – this is an inefficiency • The extra chamber though, in relation to the fish, allows a double circulation to occur and remember that amphibians are able to breathe at a more significant level through their skin as well.

Specialized Internal Transport • Birds and Mammals • High energy requirements means lots of oxygen delivered quickly to the entire body and wastes to be removed. Two more adaptations: • Oxygenated and deoxygenated blood must be kept completely separate – a fourth chamber for the heart • Two atria and two ventricles • Blood enters right atrium, drops to right ventricle then pumped to lungs (oxygenation) • From the lungs back to the heart and into left atrium, down into left ventricle and out into the aorta and then other arteries. • Blood pressure is maintained by arterial system

Mammalian Circulatory System • Discoveries over time • Ancient Greeks – heart was seat of intelligence • Galen (Greek physician) – in second century theorized that blood ebbed and flowed like tides • Arteries and veins were separate and blood flowed out of each to the body • William Harvey – in the seventeenth century theorized that we have a cyclic circulatory system • Was never able to find the point were blood stopped traveling away from heart and started back • Marcello Malpighi – in 1657 identified capillaries to back Harvey’s findings

Mammalian Circulatory System • Three primary closed cycles: • Cardiac circulation = pathway of blood within the heart • Pulmonary circulation = blood from the heart to lungs and back • Systemic circulation = blood from the heart to the rest of the body Facts • male has 5 to 6 litres while a female has 4 to 5 litres of blood • 80-90% of blood is in systemic system, most of rest is in pulmonary system • There are three main elements to a circulatory system: • Transport medium – fluid being moved around (talk about next) • Transport vessels – fluid from one area to another (later) • A pumping mechanism (last)

Transport Medium • Blood – collection of specialized cells and is therein considered a tissue • Contains two distinct elements: • Plasma = 55% of blood • Water, gases, proteins, sugars, vitamins, minerals, waste • Cells = 45% of blood • Red blood cells (44%), White blood cells, Platelets

Blood Cells • Red Blood Cells – Erythrocytes (44%) • Average male has 5.5 million rbc/ml of blood • Specialized for oxygen transport (each rbc is packed with 280 million molecules of the pigment hemoglobin) and transports 98% of O2 in body • Each hemoglobin molecule contains 4 iron atoms which each have a binding site or heme group • In theory 4 molecules of oxygen can bind to one molecule of hemoglobin

Blood Cells • Other important facts about erythrocytes: • O2 forms a loose bond with the heme group whereas CO forms a strong bond. • 45% of CO2 is carried by erythrocytes forming a compound called carbaminohemoglobin. • 9% is carried in the plasma. • The rest combines with water to form carbonic acid (H2CO3) • This keeps the partial pressure of CO2 in the blood low so that more CO2 can diffuse out of cells. • Carbonic acid will dissociate into H+ ions and HCO3- ions. This would increase the acidity of the blood however hemoglobin also picks up and rids the body of H+ ions to maintain blood pH.

Blood Cells • Death of an erythrocyte • Lives 3-4 months • Travels to the liver where much of the iron is salvaged and recycled • One to two million rbc’s replaced every second • Any reaction that causes a reduction of O2 in blood will cause our bone marrow to increase production of rbc’s • People who travel to high altitudes might increase the number of rbc’s by a factor of 2 • Sport training?

Blood Cells • White blood cells – Leukocytes • Leukocytes = 1% of blood however their number will double when fighting infection (pathogens) • Have a nuclei and appear colorless • Macrophages = phagocytic cells that can pass through capillary walls to engulf and digest pathogens and pseudopodial action to move. • Part of the body’s innate immune response which is the body’s generalized response to infection.

Blood Cells • Lymphocytes – non-phagocytic cells that facilitate the body’s acquired immune response • Enables the body to recognize and fend off specific pathogens • Two main types of lymphocytes: • T cells = mature in thymus • B cells = arise in bone marrow • Several kinds of each in the body that contribute to specific parts of the immune response • Can not only fight disease but also can become a variety of cell types under particular conditions • Enter bone marrow and become rbc’s • Enter other tissues can play role of different kinds of connective tissues

Blood Cells • Platelets – not actual cells but fragments of cells created when larger cells in the bone marrow break apart. Extremely vital to blood clotting. • Contain no nucleus and break down quickly in blood (7-10 days). • Blood will not clot unless a blood vessel is broken • Substances released by the broken blood vessel will attract platelets • As the platelets collect they will rupture and release certain chemicals • These chemicals combine with others in the plasma to produce the enzyme thromboplastin. • If Ca2+ is present, thromboplastin will combine with prothrombin (protein created in liver) to produce thrombin. • Thrombin is an enzyme that reacts with fibrinogen (another plasma protein) to produce fibrin. • Fibrin is an insoluble material that forms a mesh of strands around the wound and stops cells from escaping.

Plasma • Fluid portion of the blood but it has many functions: • Contains substances that ensures blood’s well-being and maintenance • Serum albumin = maintains blood volume and pressure • Serum globulin = antibodies to defend against disease • Fibrinogen = blood clotting • Transport of CO2 in the form of H2CO3 • When fibrinogen and other clotting agents removed the liquid that remains is called serum. • Serum immune to a particular disease (even if from an animal) can be injected into a patient to provide temporary immunity to that disease.

Human Blood Groups • Due to Harvey’s findings = transfusions • Within 50 years of his work • Many successful however dramatic failures as well. Transfusions were outlawed in 1678 in England. • Early 1900’s the major blood groups were identified. • A, B, AB, O (p. 247, table 1) • Characterized by presence or absence of two protein markers on the walls of the rbc’s. • Agglutination if improper blood types mixed • Universal Donor  Type O blood • Universal Acceptor  Type AB blood

Human Blood Groups • Rhesus factor – another protein marker • If you have it you are Rh+, if not Rh– • An Rh- individual can donate to an Rh+ individual however… • An Rh+ donor into Rh- recipient is usually okay as the anti-Rh antibodies develop over two to four month period after the transfusion. A second transfusion would be deadly as the body now has the appropriate antibodies for an immediate response (same as an inappropriate ABO transfusion).

Transport Vessels • Arteries – blood away from heart • Arterioles • Oxygenated blood* • Three different structural layers: • Outer = connective tissue and elastic fibres • Middle = thickest and contains elastic fibres and smooth muscle • Inner = smooth epithelial cells (reduce friction) • Elasticity is key for pressure (p. 250, fig 1) • Veins – blood to the heart • Venules • Deoxygenated blood* • Less elasticity but greater capacity (2x as much blood) • Thinner wall and larger inner circumference then artery • Gravity defied due to skeletal muscle and valves in veins (p. 250, fig 1)

Transport Vessels • Capillaries • Smallest blood vessel (8 um in diameter) • Regulates movement of fluids into and out of blood • Blood flows quickly however friction in capillaries slows blood down to allow nutrient and waste exchange to occur (p. 252, fig. 3) • *Exception to the rule* • Pulmonary artery carries deoxygenated blood from heart to lungs and pulmonary vein returns oxygenated blood from the lungs to the heart.

Mammalian Heart • Pumps 70 times per minute (90000 times/day) • Pumps fluid through 160 000 km of vessels • Steady flow by adjusts quickly to demands of increases and decreases in pressure • Pumps in two directions at once with no mixing of fluids • Life expectancy of ~ 80 years • All this in the size of your fist

Mammalian Heart • Blood enters the atria (left and right) and exits from the ventricles (left and right) • The atria contract simultaneously as do the ventricles. • As blood returns from the body it is collected in the superior vena cava which flows into the right atrium • Blood then is pumped into the right ventricle as the atria contract and then blood is moved out to the pulmonary arteries as the ventricle contracts • The same process is going on on the other side of the heart as blood is returning from the lungs in the pulmonary veins into the left atria. • This blood is pumped to the left ventricle and then as the left ventricle contracts the blood is pumped out the aorta to the body.

Mammalian Heart • Contractions • Atria are thin walled • Ventricles are more muscular with the left ventricle being the thickest • Valves • Between the right atrium and right ventricle there is an atrioventricular valve (tricuspid) • Between the left atrium and the left ventricle there is an atrioventricular valve (bicuspid) • Between the left ventricle and the aorta and between the right ventricle and the pulmonary artery semilunar valves are used. • Lub-dub sound is created by these valves opening and closing in the heart • Lub = atrioventricular valves • Dub = semilunar valves

Mammalian Heart • Control of the Heart • The impulse that causes a heart to beat is actually in the heart itself so the heart can beat for a while on its own. • A bundle of special muscle tissue, located in right atrium, stimulates muscle fibres to contract and relax rhythmically. • This tissue is called the sinoatrial node or S-A node. Also known as the pacemaker. • S-A node gives electrical impulse to both atria and causes them to contract simultaneously. • The pulse will then reach the atrioventricular node (A-V node) located between the two ventricles to start their contraction.

Mammalian Heart • Recording a Heart Rate (p.260, fig. 3 & 4) • Electrocardiograph (ECG) can monitor all of the impulses • Small voltage increase as the electrical depolarization that accompanies contraction of the atria (P) • Large spike accompanies the contraction of the ventricles • Ventricular depolarization (QRS) • As the ventricles recover another small spike shows the electrical repolarization that precedes the next firing of the S-A node (T) • Ventricular fibrillation – ventricles contract randomly • Can be sometimes stopped. A strong electrical current to the heart and S-A node can take over again.

Mammalian Heart • Chemical Regulators • Increased activity requires increased heart rate • Running causes an increase of CO2 in blood • Receptors in blood vessels pick this up and send a signal to the medulla oblongata • Your medulla will release noradrenaline which when it reaches the S-A node will cause the node to fire more rapidly • Decreased activity changes the heart rate back • Fast heart means high blood pressure and this info is carried to the medulla, picked up by the blood vessels again • Medulla will cause the nervous system to release acetylcholine to slow down the firing of the S-A node • Epinephrine (Adrenaline) – the “fight or flight” response • If adrenaline is released into your bloodstream by your nervous system your heart rate will increase as well.

Mammalian Heart • Cardiac Output and Fitness • Amount of blood that is pumped by the heart • Measure of blood pumped from each ventricle per unit of time therein it is a measure of oxygen delivery to the body • Affected by two factors: • Heart rate (HR) • How fast the heart is beating (beats/min) • Stroke volume (SV) • Amount of blood forced out of heart each beat (mL/beat) • Cardiac Output = HR * SV = 70 * 70 = ~4900mL/min • So in the average person the total volume of blood in the body circulates about once in 1 minutes time.

Mammalian Heart • Heart Rate & Fitness • Maximum heart rate is the fastest your heart can possibly beat during activity, which decreases as you get older • The fitness relation is not is how many beats but in the length of time it takes your heart to go from maximum to resting level after activity • Stroke Volume & Fitness • How easily the heart fills with blood • Depends on volume of blood returning in veins and the distensibility or stretchiness of the ventricles • How readily the heart empties • Depends on strength of ventricular contraction and pressure exerted by artery walls • Cardiovascular exercise enlarges the ventricular chambers, increases distensibility of ventricles and strengthens ventricular walls • Strength training may simply increase thickness of ventricular walls and limit stroke volume by reducing elasticity

Mammalian Heart • Heart Defects • Common problems at birth – valves, walls dividing chambers of heart or structure of blood vessels near the heart • Septal defect – hole in the septum (separates right and left ventricles) • Oxygenated and deoxygenated blood are able to mix • Murmurs – one or more of heart valves not closing properly • Mitral valve prolapse – flaps of the mitral valve close unevenly allowing blood to flow from the left ventricle into the left atrium • Arrhythmia – irregular heartbeat (p. 267, fig. 1)

Homeostasis • Blood Pressure • Fluctuations can be created due to increased demands on the body and how readily the body reverts back to a normal level is indicative of one’s overall fitness. • High pressure – when left ventricle is pumping and this is called systolic pressure. • Low pressure – just before another contraction of the ventricles and is called the diastolic pressure. • Average is 120/80 mm of Hg and is measured using a sphygmomanometer • Hypertension – chronic high blood pressure • High pressure against arterial walls due to increase in volume or loss of elasticity • Salt = blood will retain more water, increase volume • Cholesterol = arteries will clog, reduce elasticity • Caffeine, nicotine and alcohol imitate noradrenaline and increase heart rate • Age, heredity, lack of exercise, smoking and obesity

Homeostasis • Hypertension • Plaque build up in arteries can cause damage to platelets and therein can start to lead to a blood clot (embolism). • Treatment • Exercise, better diet and medications • Aspirin – helps prevent platelets from sticking to one another • Digitalin – produced in foxgloves and is toxic at high levels however at lower levels it strengthens heart contractions and slows heart rate • Surgery • Angioplasty = fine plastic tube inserted into artery and when a constricted region is identified a balloon is blown up to force the vessel open • Coronary bypass = involves removing a segment of healthy blood vessel from one part of your body and using it to go around a blockage near the heart. • The term double or triple refers to the number of blood vessels containing blockages that must be bypassed. (p.258, fig. 3)

Homeostasis • Maintenance of water balance, pH and temperature • Lymphatic System (p. 274, fig. 1) • drains all fluids from tissues and returns them to venous system (one way system). • water and chemicals in interstitial fluid comes from blood and this has to be returned to maintain proper balance. • fine network of small, thin-walled lymph capillaries that branch throughout the soft tissue (fluid that enters into this system is called lymph [same composition as interstitial fluid and blood plasma but no proteins]). • lymph veins move lymph (via muscle movement) to thoracic duct or right lymphatic duct. • As veins do, the lymph system utilizes valves to prevent backflow.

Homeostasis • Thoracic duct • empties into venous system at left jugular vein from the neck and the left subclavian vein from the arm (drains most of body but heart, lungs and upper right body) • Right Lymphatic duct • empties at junction of the right jugular vein and the right subclavian vein. • Lymph Nodes • small round structures located on medium and large size veins (groin, neck, abdomen, armpit). Lymphocytes are non granular WBC’s that are produced in the lymph nodes. • filter particles from lymph before it enters blood, and lymphocytes act as macrophages. • tonsils are a series of three sets of lymph nodes (back of mouth, base of tongue and upper pharynx (adenoids) – swelling due to overuse. • spleen is another which collects and breaks down damaged or otherwise non-functional RBC.

Internal Systems and Regulation