Circulatory Systems: Open vs. Closed

• Here are study notes based on your document:

Transport Around the Body

• Living organisms can be classified based on whether they require circulation
• Small unicellular organisms depend on diffusion and do not need a transport system
• Diffusion in small organisms works due to a large surface area to volume ratio, small diffusion distance, steep concentration gradient, and low energy requirements
• Larger organisms require a transport system known as the circulatory system
• Circulation can be open or closed

Open vs Closed Circulation

• Open circulation only has a heart with no blood vessels
• Closed circulation features a heart and blood vessels that enclose the blood
• Types of closed circulation include single and double circulation

Single Circulation

• Single circulation is found in fish
• Blood passes through the heart once per cycle in single circulation
• Blood is pumped from heart to gills for oxygenation, then to tissues, before returning to the heart

Double Circulation

• Double circulation is found in birds and mammals
• Blood passes through the heart twice per cycle in double circulation
• Double circulation consists of pulmonary and systemic circulation

Pulmonary and Systemic Circulation

• Pulmonary circulation is between the heart and lungs
• Systemic circulation is between the heart and body tissues
• In pulmonary circulation, deoxygenated blood is pumped from the right side of the heart to the lungs, then oxygenated blood returns to the left side
• In systemic circulation, oxygenated blood is pumped from the left side of the heart to body tissues, then deoxygenated blood returns to the right side

Advantages of Double Circulation

• Complete separation of oxygenated and deoxygenated blood
• The left ventricle pumps blood at higher pressure over a longer distance
• Right ventricle pumps blood at lower pressure to prevent damage to capillaries surrounding alveoli

Heart Structure

• The heart is located in the center of the thorax
• The heart is shaped like an inverted cone, apex pointing left
• The heart is about the size of a fist (300gm)
• The heart gets its blood supply from coronary arteries
• The heart has 4 chambers: right atrium, right ventricle, left atrium, and left ventricle
• The heart has 4 vessels: pulmonary artery, vena cava, pulmonary vein, and aorta
• The heart has 4 valves: right AV valve (tricuspid), left AV valve (bicuspid), pulmonary SL valve, and aortic SL valve
• There is a septum separating the right and left sides

Function of the Heart

• The heart transports substances from high to low pressure over a distance
• This mass transport helps larger organisms overcome the limitations of diffusion

Circulation Through the Heart

• Deoxygenated blood enters the right atrium via the vena cava
• Deoxygenated blood is pumped from the right atrium to the right ventricle
• Deoxygenated blood is pumped from the right ventricle to the lungs via the pulmonary artery for oxygenation
• Oxygenated blood returns to the left atrium via the pulmonary veins
• Oxygenated blood is pumped from the left atrium to the left ventricle
• The left ventricle pumps oxygenated blood to body tissues via the aorta

Pulmonary and Systemic Circulation

• Pulmonary circulation involves steps 3 and 4 only
• Systemic circulation involves steps 1 and 6 only

Role of Valves

• Valves allow blood flow in one direction and prevent backflow
• Valves open when pressure before the valve is higher than after the valve

Atrioventricular Valves

• A.V. valves allow blood flow from atria to ventricles during atrial systole
• A.V. valves prevent backflow during ventricular systole
• A.V. valves are held by tendons attached to papillary muscles

Semilunar Valves

• Semilunar valves allow blood from ventricles into major arteries during ventricular systole
• During diastole, pressure in arteries is higher than in ventricles, causing blood to collect in pockets to close the semilunar valves

Cardiac Cycle

• Diastole (0.4s): both atria and ventricles are relaxed, atria pressure is slightly higher, AV valves are open, SL valves are closed, and the ventricles fill from 0% to 70%
• Atrial systole (0.1s): atria contract and ventricles relax, atria pressure is higher, AV valves are open, SL valves are closed, and the ventricles fill from 70% to 100%
• Ventricular systole (0.3s): ventricles contract and atria relax, ventricles pressure is higher, AV valves are closed, SL valves are open, and the ventricles empty from 100% to 0%

Pressure Changes During Cardiac Cycle

• Bicuspid valves are the lower 2 on a pressure graph, and semilunar valves are the higher 2
• The labels on a typical pressure graph in clockwise direction are: Close – Open – Close – Open
• A: Bicuspid valve closes when pressure in the ventricle exceeds pressure in the atrium
• B: Semilunar valve opens when pressure in the ventricle exceeds pressure in the aorta
• C: Semilunar valve closes when pressure in the aorta exceeds pressure in the ventricle
• D: Bicuspid valve opens when pressure in the atrium exceeds pressure in the ventricle

Important Definitions

• Heart Rate: number of heartbeats per minute
• Stroke volume: volume of blood pumped in one beat
• Cardiac output: volume of blood pumped in one minute (HR × SV)

Special Features of the Cardiac Muscle

• The cardiac muscle is the strongest in the body that keeps beating throughout life
• The cardiac muscle can initiate its rhythm through the SAN (Sino-Atrial Node) in the right atrium (pacemaker)

Blood Vessels: Arteries

• Arteries have a narrow lumen and thick wall
• Arterial walls consist of 3 layers: Tunica intima, Tunica media, and Tunica adventitia
• Tunica intima is a single layer of cells (endothelium)
• Tunica media contains elastic fibers, smooth muscles, and connective tissue
• Tunica adventitia consists of collagen fibers, smooth muscles, and connective tissue
• Arteries have more elastic fibers and smooth muscles, and arteries lack valves
• Arteries experience the highest pressure

Role of Elastic Fibers

• During ventricular systole, elastic fibers stretch to prevent pressure from becoming too high and protect the artery
• During diastole, elastic fibers recoil to prevent pressure from getting too low

Adaptations of Arteries

• Thick walls withstand high pressure
• Narrow lumen maintains high pressure
• No valves needed as pressure is too high

Adaptations of Layers

• Tunica intima: smooth to reduce friction, folded to avoid damage when the wall stretches
• Tunica media: elastic fibers recoil during diastole, smooth muscles contract or relax for distribution of blood
• Tunica adventitia: collagen fibers protect from bursting or external traumas

Blood Vessels: Veins

• Veins have a wide lumen and thin walls
• Walls have the same 3 layers as arteries but less developed, with fewer elastic fibers and smooth muscles
• Valves are present in veins
• Veins have the lowest pressure

Blood Vessels: Capillaries

• Capillaries have a narrow lumen and very thin walls to shorten diffusion distance
• Capillaries have pores for substance exchange
• Capillaries lack elastic fibers or smooth muscles and lack valves
• Capillary pressure is higher than veins but lower than arteries

Factors Ensuring Blood Flow in Veins

• Negative pressure in the thorax during inspiration causes suction
• Muscle pump pushes blood towards the heart
• Valves prevent backflow

Causes of Blood Pressure Reduction in Capillaries

• Leakage of fluids through capillary pores
• Long distance from the heart
• Large total surface area

Blood Components

• Blood consists of Plasma (55%) and Cells (45%)
• Plasma is the liquid part of the blood, 90% water
• Plasma contains dissolved substances (10%): glucose, salts, minerals, hormones, enzymes, wastes
• Plasma also contains plasma proteins: fibrinogen, albumin, and globulin
• Cells consist of RBCs, WBCs and Platelets

Functions of RBCs, WBCs, and Platelets

• Red blood cells transport oxygen
• White blood cells facilitate immunity
• Platelets aid in blood clotting; platelet count is about 150000 – 400000/ mm³

Blood Clotting Advantages

• Prevents loss of health by entry of microorganisms
• Prevents blood loss

Mechanism of Blood Clotting

• Damaged tissue secretes thromboplastin protein
• Platelets are activated by thromboplastin, forming a platelet plug and secreting more thromboplastin
• Thromboplastin converts prothrombin to thrombin
• Thrombin converts fibrinogen (soluble) to fibrin (insoluble)
• Fibrin threads form a mesh to trap blood cells creating a blood clot
• Process requires Calcium and Vitamin K

Important Terms

• Energy budget: relationship between energy input and output
• Energy input: food intake
• Energy output: exercise

Obesity & BMI

• Obesity results from higher energy input than output
• Weight reduction occurs when output exceeds input
• Balanced diet and regular exercise are necessary to maintain a healthy weight

Body Mass Index (BMI)

• The Body Mass Index (BMI) indicates obesity levels
• Formula: BMI = weight (kg) / (height (m))^2
• Ranges: underweight (less than 18.5), normal weight (18.5 to 24.9), overweight (25.0 to 29.9), and obese (30.0 or above)

Cardiovascular Diseases: Abnormal Blood Pressure

• Blood pressure: pressure exerted by blood on vessel walls, measured using a sphygmomanometer
• Normal blood pressure: About 120/80 mmHg
• Blood pressure varies with age, level of activity, position, and time of day
• Hypertension: reading above 140/90 mmHg sustained and measured at rest
• Hypotension: pressure reading below 90/60 mmHg at rest

Atherosclerosis

• Characterized by thickening and hardening of a blood vessel wall, resulting in a narrowed lumen
• Narrowing caused by fibro-fatty plaque
• Fatty deposits form atheroma
• Blood clot forms thrombus

Pathology of Atherosclerosis

• Damage to endothelial lining of vessels due to hypertension, smoking (tar), and free radicals
• Triggers inflammatory response that leads to accumulation of cholesterol = atheroma
• Collagen fibers form a fibro-fatty plaque
• Atherosclerosis causes hypertension

Consequences of Atherosclerosis

• Incomplete block = Reduced blood supply (Ischemia) = Angina pectoris
• Complete block of blood vessels = Myocardial infarction (heart) or stroke (brain)
• Weakness = Aneurysm (may rupture)

Angina Pectoris

• Incomplete block of heart vessel = Reduced blood supply = Anaerobic respiration and lactic acid build-up
• Symptoms: severe chest pain during exercise, relieved by rest and vasodilators

Myocardial Infarction

• Complete arterial block = Death of cardiac muscle
• Complete arterial obstruction = No oxygen or glucose to cardiac muscle = No aerobic respiration
• Heart undergoes anaerobic respiration = Lactic acid produced (lowers pH) = Enzymes denature = Death of tissue
• Symptoms: severe chest pain at rest, not relieved by vasodilators

Risk Factors of Cardiovascular Diseases: Non-Modifiable

• Genetic: familial CVD history
• Gender: more common in males, estrogen protects females before menopause
• Age: the elderly are at a higher risk

Risk Factors of Cardiovascular Diseases: Modifiable

• Smoking: increases the risk of CVDs: Nicotine increases adrenaline, while CO damages endothelium and decreases oxygen delivery
• Diet: Certain varieties increase CVD (cholesterol and LDL, high salts), while others reduce CVD risk: HDL removes lipids, vitamins act as antioxidants

Risk Factors: More Diet

• High total energy input
• High cholesterol
• High LDL:HDL ratio
• High saturated fats
• Diet rich in salts
• Alcohol consumption
• Caffeine consumption
• Exercise: doubles risk, so regular exercise cuts risk in half
• Obesity: Risk increases if Waist / Hip ratio is higher than 0.8-0.9 for women and 0.9-1.0 for men
• Stress: Stress leads to high adrenaline, which increases blood pressure

Treatment of Cardiovascular Diseases: A. Lifestyle Modification

• Quitting smoking
• Regular exercise
• Reduced cholesterol intake and LDL:HDL ratio
• Avoiding animal fats, increase plant oils
• High levels of vitamins
• Reducing /stopping alcohol and caffeine consumption
• Avoid stress

Treatment of Cardiovascular Diseases: B. Drugs

• Antihypertensives control pressure through diuretics, increasing urine volume, and vasodilators, widening vessels
• Anticoagulants reduce clotting
• Statins minimize cholesterol formulation
• Other: plant sterols and antioxidants control fat absorption and free radicals and endothelial inflammation, respectively

Drug Side-effects

• Diuretics can cause hypotension, dehydration, kidney problems
• Vasodilators can cause headaches and dizziness
• Anticoagulants could cause severe bleeding
• Statins can cause constipation, muscle aches, and liver damage

Cardiovascular Treatment: C. Surgical Options

• Surgical: angiography, coronary bypass, heart transplant

Epidemiology of Cardiovascular Diseases

• A branch of medical science dealing with the incidence, distribution, and control of diseases in a population

Actual vs Perceived Risk

• Actual Risk is the probability a thing will happen at a given time
• Perceived risk is community understanding of certain risk elements

Key Concepts

• Causation: change in one variable is responsible for change in another, proved by laboratory tests
• Correlation: change in one variable is accompanied by change in another, proved by statistical analysis, with similar patterns equaling positive correlations, and the opposite equaling negative ones

Study Designs

• Case Control: one group has the disease while one does not, researcher compares their past exposure to risk factors
• Cohort Study: Divide normal population in 2 groups, expose one group, and measure progress over time

Evaluating Studies

• Repeated: other people get similar results
• Representative: large and random to represent the whole population
• Fair: not unbiased
• Valid: correct methods & accurate measurements

Evaluating Study Notes

• Sample size shows variation
• Sample selection: controlled variables such as age, gender, level of activity, etc...
• Statistical analysis
• Duration of the study: the longer the duration, the better the study
• Error bars show the spread of data around the mean; the larger the bar, the lower the reliability

Examination Tips for Graphs

• Include trend, pattern, and data manipulation with commentary on graphs
• Do not extrapolate
• To find the cardiac cycle from a Pressure diagram, find the time between two repeated cycles, or the peaks on the x-axis

Control Drugs

• A placebo is inert
• A placebo is used to control psychological response

Causes for Death

• Morbidity = disease
• Mortality = death caused by the disease
• Look at pattern changes in the graphs for the disease

Biological Molecules Bonding

• Hydrogen bonds: weak bonds between slightly charged atoms
• Ionic bonds: strong bonds between strongly charged ions
• Disulfide bridges

Polar vs Non-Polar Molecules

• Non-polar: even distribution of charges
• Polar: uneven distribution of charges, either unipolar or dipolar

Properties of Water

• Water molecules are non-linear and dipolar due to atom sizes and charge
• Dipolar due to charge, which allows hydrogen bonds with all polar particles = excellent solvent
• Cohesion-attraction forms unbroken columns
• Transport medium.
• Excellent Solvent
• Amphoteric: buffer to keep constant pH
• Transparent for sunshine and aquatic life
• Low Density for insulation
• High specific heat capacity (SHC) for enzyme activity

Organic Molecules key Definitions

• Molecular Formula: Number of each atom: Glucose is C6H12O6
• Structural Formula: Arrangement of atoms in a molecule, like ring form
• Monomers: subunits bonded by condensation reactions
• Isomers: Molecules having the same formular but different structures; alpha & beta Glucose
• Macromolecule: monomers
• Polymer: Macromolecule made of identical monomers
• Condensation: Removing water makes a polymer
• Hydrolysis: Adding water brakes down a polymer

Polymer Breakdown

• Polymers are macromolecules, not all macromolecules are polymers
• Polypeptides and polysaccharides are polymers
• Lipids are not polymers, made of fatty acids & glycerol

Carbohydrates (CH2O)n

• Monosaccaraides: one
• Trioses: 3 carbons; C3H6O3
• Pentoses: 5 carbons; C5H10O5
• Hexoses: 6 carbons; C6H12O6, = Glucose, Galactose Fructose

How to Draw Glucose:

4. Draw an empty ring
5. Draw carbon number
6. Add OHs (All down except 3 up).
7. add H