Circulatory system

• The circulatory system consists of blood, blood vessels, and the heart.

Blood Pressure

• Blood pressure measures the force of blood against artery walls.
• High blood pressure can result from narrower arteries or increased blood volume.
• Blood pressure can be impacted by sodium levels.
• Giraffes blood pressure much higher than human's

Functions of Blood

• Blood carries oxygen, nutrients, and hormones to cells.
• It transports waste products like carbon dioxide and urea away from cells.
• Blood helps protect the body against blood loss, injury, and toxic substances.
• It works with the digestive, respiratory, and endocrine systems.
• Blood regulates body temperature.

Circulation Necessity

• Unicellular organisms don't need a circulatory system. Gas exchange occurs directly with the environment.
• Simple multicellular organisms have simple circulatory systems with thin membranes for gas exchange.
• Complex multicellular organisms need a complex circulatory system for oxygen and nutrient delivery.

Evolution of Circulatory Systems

• Mammals have evolved circulatory systems tailored to high metabolic needs.
• Mammalian circulatory systems keep oxygen-rich and oxygen-poor blood separate by use of a 4 chambered heart.

Blood Composition

• Blood is a tissue composed of specialized cells.
• Blood consists of plasma (55%) and formed elements (45%).
• Plasma is the fluid portion of blood, composed of 90% water and 10% protein.
• Plasma proteins, such as albumin (controls amount of water), fibrinogen (helps with blood clotting), and globulins (transports lipids) comprise 10% of the plasma.
• Plasma also contains oxygen, carbon dioxide, glucose, minerals, and ions such as sodium, potassium, and chloride.

Plasma vs. Serum

• Plasma is the liquid portion of blood treated with anticoagulants to prevent clotting, retaining clotting factors.
• Serum is the liquid remaining after blood clots, lacking clotting factors because they have been used up.

Red Blood Cells (Erythrocytes)

• Red blood cells transport nutrients and eliminate waste.
• They are created by stem cells in the long bones.
• Mature RBCs are tiny, lack mitochondria, and lack a nucleus.
• The biconcave shape maximizes surface area for gas exchange.
• Cytoplasm contains hemoglobin, which has iron molecules and a high affinity for oxygen.

White Blood Cells (Leukocytes)

• White blood cells defend against pathogens.
• They are created from stem cells in bone marrow.
• They appear colorless and amoeboid shapes

Types of White Blood Cells

• Neutrophils destroy pathogens through phagocytosis.
• Lymphocytes control immune responses and produce antibodies.
• Phagocytosis is the process of engulfing pathogens.
• Pus is formed in wounds from dead bacteria

Platelets

• Platelets help the blood to clot, and protect the body from blood loss after an injury.
• They are fragments of larger cells from bone marrow, therefore not cells themselves.
• Platelets lack a nucleus.
• Blood Clotting: Platelets adhere to torn vessel edges, initiating clotting.
• They release chemicals that initiate clotting factors.
• Chemicals cause platelets to stick to collagen fibers in vessel walls.
• Fibrinogen conversion produces a mesh that acts as a clot.
• The clot traps red blood cells to form a scab.

Circulatory systems

• A pump such as the heart
• A system of blood vessels
• Blood

Open vs Closed Circulatory Systems

• Open: cells bathed in blood, blood pumped into cavities (e.g., snails, insects, crustaceans.)
• Closed: blood contained in vessels, separated from interstitial fluid (e.g., earthworms, squids, vertebrates.)

Blood Vessels

Types of blood vessels

• Arteries
• Arterioles
• Capillaries
• Venules
• Veins

Double Circulation System

• Pulmonary Circuit: Between heart and lungs for oxygenation.
• Systemic Circuit: Between heart and body for nutrient/waste exchange.

Pulmonary Circuit

• Deoxygenated blood flows to lungs via pulmonary arteries.
• Oxygenated blood returns to the left heart via pulmonary veins.
• It is a low-pressure system.

Systemic Circuit

• Oxygenated blood is pumped from the left ventricle into systemic arteries to body parts.
• Deoxygenated returns to the right atrium via systemic veins.
• It is a high-pressure system to propel blood long distances.

Arteries and Arterioles

• Arteries and arterioles have a small inner diameter and thick elastic walls.
• The structure contains 3 layers of strong tissue.
• The outerLayer is connective with elastic fibers
• The middle layer is smooth muscles
• The inner layer is single epithelial cells.
• These vessels withstand pressure and ensure correct blood flow direction.

Arteries

• Arteries carry oxygenated blood away from the heart, except for pulmonary arteries.
• One exception, pulmonary arteries carry deoxygenated blood away from the heart.
• Coronary arteries supply oxygenated blood to heart muscle cells.
• The aorta is the largest artery, connected directly to the heart.
• Arteries stretch with heart contractions making room for more blood flow then recoils which is a pulse.

Arterioles

• Arterioles are controlled by the nervous system, smaller than arteries, and have smoother walls.
• They carry blood away from the heart to the tissues of the body.
• Vasodilation (increases blood flow/releases thermal energy) occurs when the body is hot.
• Vasoconstriction (restricts blood flow/reduces thermal energy loss) moves blood to areas that need it most.

Capillaries

• Located between arteries and veins
• Structure
  • Smallest blood vessels
  • Fine networks decrease flood flow
  • No smooth muscles
  • Extremely tiny cells
• Function
  • Gas exchange
  • More time for gas exchange

Pre-Capillary Sphincter Muscles

• They are located between arterioles and capillaries
• They constrict and dilate capillaries to control blood flow.
• It is constricted when its not needed
• It dilates when more blood is needed

Veins

• Veins thinner and less elastic than arteries
• Inner diameter is larger than arteries
• Veins have one way valves.
• Functions: Carries deoxygenated blood towards the heart except for pulminary veins
• They also carry CO2 and waste away from the cell

Valves in Veins

• One way valves keeps blood flowing towards the heart (with gravity)
• Process: skeletal muscles squeeze veins, and valves open/close, and blood moves towards heart.
• Blood pooling:
  • When muscles become weak and don't contract enough

Heart Structure

Location and Protection

• The heart is located in the middle of the chest and protected by ribs, spine, and sternum.
• It's a muscular pump made of endocardium (inner lining) and myocardium (cardiac muscle).
• It contains a built in pacemaker

Chambers

• The heart consists of 4 chambers: 2 atria and 2 ventricles.
• The Atria recieve blood returning to heart

Atria

• The left atrium receives oxygenated blood from the lungs.
• The right atrium receives deoxygenated blood from the body cells
• Ventricles recieve atria blood from Atria out to pumps blood out

Ventricles

• The left ventricle pumps oxygenated blood to the body.
• Right ventricle pumps deoxygenated blood to lungs.
• Chambers are separated by heart valves stabilized by heart strings.
• Valves prevent backflow of blood

Heart Valves

• There are Atrioventricular and Semilunar valves.
• Septum divides the heart into 2 pumps.
• The septum is a muscular wall.

Left Ventricle Hypertrophy

• It is when the muscle tissue in chamber wall thickens.
• Thickening occurs from stress/strain, overwork on heart chambers.
• This thickens the heart, and makes it the main pumping chamber
• Increased blood pressure occurs in heart, which can cause stiff heart.
• The most common cause of this is long term and or choric blood pressure

Blood Flow Pathway - Deoxygenated

• Blood starts in body ->lungs
• Right side of heart and Think RIGHT goes to the LUNGS.
• Blood flows from body -> superior/inferior vena cava ->right atrium ->tricuspid valve ->right ventricle -> semilunar valve (via contraction)-> pulmonary arteries ->lungs

Blood Flow Pathway - Oxygenated

• Blood starts in Lungs ->body.
• Left side of heart and Think: blood LEFT the lungs
• Flows Oxygen from lungs->pulmonary veins->left atrium->bicuspid valve->left ventricle ->semilunar valve (contraction) ->aorta->body.

Major Arteries

• Coronary: heart
• Carotid arteries: brain, head, face, neck
• Femoral: Legs.
• Celiac: Digestive

Blue Baby Syndrome

• The heart isn't normally divided so oxygenated blood doesnt mix.
• Congenital Defect: Oxygenated blood mixing can lead to circulation issues.

Cardiac Cycle

• complete heartbeat involving contraction and relaxation.

Phases

• Diastole is when ventricles relax as filled with blood.
• Systole is when ventricles contract so blood moves out.
• The Atria Begin to fill with blood. Then pushes AV valves during blood flow.
• Atria contract during blood flow. Then, Venti contract forcing closed AV valves, which remains close to sl valves. Later Venticles contract, with fully sl valves. Then, forces blood into arteries.

Heart Sounds

• The Heartbeat produces" Lub-Dub":
• Lub=closing of tricuspid and biscuspid valves with constracting ventricals
• Dub=Closing of semilunars ventricles while they relax Blood filling up antria

Cardiac Contractions

• Heart= Myogenic and can contract (without external stimuli)
• The heart can contract and relax on its own
• It has Nodes and Involves. -SA node which maintains pumping rhythm
  • AV node
  • Bundle of his with purkinje fibres.

Heart rate Regulation

• It is Regulated by the Nervous System Hormones and Endocrine.

Blood pressure regulation

• It happens as a result to experience force in the beating
• It is measured pressure in ventricles in the the hearts as it either contracts/relaxes
• It is measured in mercury (mm Hg)
• Normal =120/80 mm Hg

Systolic/ Diastonic

• Systolic highest: This happens with the contraction.
• Distolic this is least: it happens with the relaxation of.
• Factors of bp (130 mm Hg) in diastolic and (80mm Hg). Can lead to heart attack and stroke.
• High blood pressure is a big risk to our health
• Avoid stress bad drinks

Heart Health

• Myocardial: Artery Sends with blood and oxygen heart block and it a buildup of the plaque called Atherosclerosis. Plaque breaks during blood flow due to the cause of the stroke from the blockage of oxygen.

Stroke

• Artery in brain is damaged, from clot blocking (Ischemic stroke) or hemorrhages stroke due to damage And bleeding in the brain caused by built-up.
• Stroke Symptoms: FAST - Face Drooping, Arm Weakness Speech and time.
• Medical Emcengy!