Cardiovascular System: Heart and Blood Vessels

Cardiovascular System

• Blood circulates continuously through the circulatory system
• The heart acts as a pressure pump, driving blood flow

Circulatory System Circuits

• The pulmonary circuit involves the heart and lungs
• The systemic circuit involves the heart and the rest of the body
• Blood remains within blood vessels at all times, establishing a closed circulatory system

Blood Vessels

• Arteries transport blood away from the heart
• Veins transport blood back to the heart
• Capillary beds enable the exchange of blood and tissues

Heart Location

• Situated in the mediastinum
• It is medially located inside of the thorax cavity, slightly off-center to the left
• The heart is anterior to the vertebral column
• It sits superior to the diaphragm
• It lies in the thoracic cavity and abdominal cavity
• Flanked and partly obscured by the lungs

Heart Enclosure

• The pericardium is a double-walled sac enclosing the heart
• Serous and fibrous membranes comprise the pericardium

Pericardium Layers

• The pericardium consists of several tissue layers
• The fibrous pericardium (dense connective tissue) protects, anchors, and prevents overfilling
• The serous pericardium (serous membrane) lies deep to the fibrous pericardium
• It forms a sac surrounding the heart with parietal and visceral layers
• The layers of serous membrane are separated by a fluid-filled pericardial cavity

Myocardium

• The myocardium is the heart muscle
• Striated cardiac muscle cells, called cardiomyocytes, form a hollow muscle
• Cardiomyocytes are mechanically interconnected by connective tissue fibers (cardiac skeleton)
• The Cardiac Skeleton provides structural support & electrical insulation between heart sections

Cardiomyocyte Characteristics

• Cardiomyocytes have no origin and no insertion
• Intercalated discs act as tendons and desmosomes work as push buttons
• Cardiomyocytes form membrane-membrane connections

Functional Subunits

• The heart contains two functional and contractile subunits with right and left atria, right and left ventricals
• The four chambers are electrically insulated from each other
• This insulation allows the chambers to contract independently
• Systole is contraction, usually describing ventricals
• Diastole is relaxation, usually describing ventricals
• Ventricular systole corresponds to atrial diastole

Atrial and Ventrical Contraction

• When atrial muscle cells are excited, they contract, while ventrical muscles relax
• When the ventrical muscle cells are excited, they contract, while atrial muscles relax
• Myocardium contraction generates blood pressure

Pressure and Blood Flow

• Atrial pressure fills ventricles
• Ventricular blood pressure fills atria (indirectly via systemic and pulmonary routes)
• Blood pressure functions as an antagonist for the cardiac muscle system
• The heart does not have muscular antagonists

Endocardium

• Endocardium is the inner heart wall
• Squamous epithelial tissue on connective tissue lines the heart chambers and heart valves
• The epithelial lining connects to the blood vessels

Four Chambers Anatomy

• Two superior atria are separated longitudinally by the interatrial septum
• Two inferior ventricles are separated longitudinally by the interventricular system
• The right ventricle receives blood from the right atrium
• The left ventricle receives blood from the left atrium
• The right atrium receives blood from the left ventricle via the systemic circuit
• The left atrium receives blood from the right ventricle via the pulmonary circuit

Blood Vessels

• Afferent blood vessels bring blood back to the heart
• Veins are afferent blood vessels
• Efferent blood vessels take blood away from the heart
• Arteries are efferent blood vessels
• Atria fills ventricals, ventricals fill arteries, veins fill the atria
• The pulmonary circuit is driven by the right side of the heart (right atrium/ventricle)
• The systemic circuit is driven by the left side of the heart (left atrium/ventricle)

Circulatory System

• Veins connect and bring blood to the atria
• Atria connect and bring blood to ventricles
• Ventricles connect to arteries that take blood away
• The arterial system transitions into the venous system in capillary beds
• The right side of the heart drives the pulmonary circuit
• The left side of the heart drives the systemic circuit

Pressure Operated Valves

• Pressure-operated valves in afferent (veins) and efferent (arteries) blood vessels
• Valves between atria and ventricles ensure unidirectional, pressure-driven blood flow
• Heart valves are connective tissue flaps that open and close
• They open and close in response to blood pressure changes during heart contractions

Atrioventricular Valves

• During atrial contraction, blood returning to the heart fills the atria, which forces the AV valves to open
• As the ventricles fill, AV valve flaps hang limply into vents
• Atria contract, forcing additional blood into ventricles
• AV valves open when arterial pressure is greater than ventrical pressure

Ventricles Valves

• Ventrical pressure closes AV valves during contraction
• Ventrical contraction forces blood against the AV valve cusps
• Papillary muscles contract and chordae tendinae tighten preventing valve flaps from everting
• AV valves close; arterial pressure is less than ventrical pressure

Semilunar Valves

• Valves in afferent veins work in same way as semilunar
• High blood pressure upstream forces semilunar valves open
• High blood pressure downstream forces semilunar valves closed

Left Ventricle Force

• The left ventricle is stronger than the right ventricle
• This makes the left ventricle more capable of generating force and pressure

Ventricle Volume

• Logic does not dictate that the left or right ventricles are larger. That is, they are roughly the same size

Heart Oxygen and Nutrients

• Muscle contraction consumes substantial energy
• Energy metabolism using aerobic respiration sustains energy for extended periods
• Nutrients and O2 fuel this system to produce energy
• The circulatory system transports O2 and nutrients both to muscles and to other high energy-consuming tissues
• The heart is a continuously active muscle
• If the heart stops flow of blood and O2 to these tissues stop and tissues die
• To maintain bloodflow, next to the brain, hearts have top priority when it comes to O2 and nutrient supply
• The heart muscle depends on its own system (coronary blood vessels) for proper function
• Severe coronary blood vessel blockage irreparably damages cardiac tissue resulting in compromised heat function

Heart Physiology

• The heart muscle is composed of striated cardiomyocytes
• Cells branch and connect along intercalated discs
• Intercalated discs create firm mechanical joints between cells by desmosomes
• Myocardium as a result of intercalated discs, is a electrical synctium formed by gap junctions
• Cardiac action potentials spread from cell to cell
• Calcium and sliding filaments dictate cell movement and contractions

No Motor Neurons

• Cardiomyocytes do not operate using motor neurons

Contraction Control

• The human heart is not innervated by motor neurons
• Its a myogenic heart
• Contraction is controlled by intrinsic "pacemakers"
• These specialized cardiomyocytes regularly auto-depolarize and spreads the pulse over entire myocardium

Skeletal Muscle Differences

• Skeletal muscles have shorter action potentials
• AP Plateau due to Calcium
• AP is Longer in duration, preventing tetanus

Electrical Sequence in Myocardium

• Electrical depolarization triggers contraction
• Several pacemaker centers exists with differing Spontaneous Electrical Depolarization Frequencies
• The SA node serves as the primary pacemaker as it has the fastest time
• SA nodes dictate rhythm on secondary and tertiary centres inside myocardium

Redundancy

• Intrinsic pacemakers have redundancy
• Secondary pacemakers take over if primary fails and vice versa
• Tissue barrier Electrically Isolates Atria and Ventricles

Electrophysiology

• Stratiated muscles dont have a Not Transmitted Motor Neuron
• Action Potentials are carried by Ca2+ ions
• Longer time that Skeletral Muscle

Pacing Potentials

• Spontaneous Potential is generated by Pacermakers
• Calcium ions, open gated channels and conduct action
• Gap junctions over myocardium

Electrolyte Imbalances

• Membrane potential alterations affect AP generation and repolarization
• Ion flow kinetics is altered across membrane, depending on Ca or K concentrations with rate changes or arrests
• Ca++: depresses rate and high disrupts function
• K: same dangers + cell death leading to arrhythmia

Factors in Regulation

• Regulatory factors include Age, Gender, Exercise, Body Temp, activity
• Tachycardia leads to fibrillation with 100 rate in stress or disease
• Brady, abnormal rate or low temp can lead to acute brain traumea
• CHF: pump inadequate
• Arteriosclerosis from fat
• 90MM HG, hypertension has to work circulation high pressure
• Heart weakened contractoins
• CardioMyopathy: Degeneration of ventricles

Contraction Imbalance

• CHF caused by imbalance of circulatory or pulmonary
• Pulmonary when left vent fails. overloads vessels in lung
• Right failure leads to Shortage circulation

Heart Defections Congeital

• Ventral: sep def 1:500
• Septum or right or systemic weakened
• Hole closure

Aorta Problem Defect

• Aortal issue narrow increased blood pressure
• widening fixes

Blood Vessesl Structures

• Blood and heart form system
• Vessel walls are 3 layers thick
• Closed heart circulates blood only in the heart.
• Veins carry blood towads
• Capiliary beds exhange blood and tissues

Structure Function

• System pressured driven
• Aorta and arteries has to pass aorta
• Contraction by heart creates force
• Hypertensions cause stress

Walls Comprise

• Inner layer contact
• Tunica intima epithileum is smooth layer
• Intertia is basement. Connective tissue
• Media layer muscles
• Outter layer is external

Media and layers help tissues

• Help vessel control sections
• Can increase or decrease blood flow
• Controlled by hormones

Arterial Vessels

• Different anatoctmically
• Thick walls Elastic Arteries have thick walls
• Elasticity doesnt play regulation in conducting
• Vasodialation regulates the blood in tissues by vasodialitoin

Contractions in Tunics

• High Smooth muscle ratio in Tunics
• Pressure by expanding

Capillaries

• Small vessel that contain only intima at the wall
• All cells go to capillaries

Continuous types in tissue membranes

• Connect tight, only few cleft
• Select cleft per plasma
• Membrane controlled exhange
• Only found in fe tissues and orgnas for repair

Veins in Organ

• Allow more passage to organ to move cells to tissues
• Walls have space for destruction of foreign
• Spinction control move
• Not outside

Cardio Types

• Ventricular or atrial
• Valves are to ensure back flwo with assistance

Anatomy and function of the cardiovascular system. Explores the different circuits, blood vessels, and the heart's location and structure within the body. Focuses on the movement of blood and its vital functions.