Anatomy and Physiology Review

• Tissues are layers of cells that cover body surfaces

Epithelial Tissues

• Epithelial cells cover the outer skin surface, including skin and airways
• Endothelial cells cover the inner surface of blood vessels
• Cells form sheets for protection or absorption, or they form glands for secretion
• STAPS is used to remember the functions of epithelial tissues: Secretion, Transport, Absorption, Protection, and Sensory reception

Structure

• Layer arrangement is classified as simple, pseudostratified, or stratified
• Simple arrangement is a single layer of cells used for absorption and filtration
• Pseudostratified arrangement is a single layer with varying cell heights
• Stratified arrangement has multiple layers of cells to provide protection

Cell Shape

• Squamous cells are flat and allow for diffusion and filtration, such as in the lungs and blood vessels
• Cuboidal cells are cube-shaped and used for secretion and absorption, such as those in the kidney tubules
• Columnar cells are tall and rectangular, used for secretion and absorption such as in the intestines

Pseudostratified Epithelium

• Single layer of cells with nuclei at the basal end of cells
• Nuclei are at different levels because adjacent cells are so tightly packed that this displaces the nuclei
• Cilia on the surface helps move mucus and trapped particles in the respiratory tract, which occurs in the airways to clear debris

Connective Tissue

• Mostly abundant and widely distributed tissue in the body
• Distinguished by a low cell density alongside a large extracellular matrix

Loose Connective Tissue

• Adipose tissue is an example and serves with fat storage Loosely woven fibers surround and cushion organs

Dense Regular

• Found in ligaments and tendons
• Fibers arranged in parallel for strength

Dense Irregular

• In the dermis and protective capsules surrounding organs
• Fibers randomly positioned for stress resistance in multiple directions

Supportive Connective Tissues

• Cartilage, made of hyaline cartilage, offers support with flexibility
• Bone, specifically compact bone, is there for structural assistance with mineral storage

Fluid Connective Tissue

• Blood and lymph carry nutrients, oxygen, and immune cells

Connective Tissues - Blood

• Red blood cells (erythrocytes) transport oxygen via hemoglobin and are disc-shaped without a nucleus
• Platelets (thrombocytes) are for blood clotting and are small and irregularly shaped
• White blood cells (leukocytes) function in immune defense

Agranulocytes

• Monocytes engulf pathogens
• Lymphocytes produce antibodies and combat infected cells

Granulocytes

• Eosinophils defend against parasites and allergic reactions
• Basophils release histamines during allergic reactions
• Neutrophils are the first responders to infections and engulf bacteria
• Some cells have granules in their cytoplasm, while others lack granules in their cytoplasm

Muscle Tissues

• Skeletal muscles are voluntary, attached to bones, and provide motion, heat, and protection, composed of long cylindrical fibers
• Smooth muscles are involuntary, located in the walls of hollow organs and blood vessels enabling slow, rhythmical contractions using spindle-shaped, non-striated fibers
• Cardiac muscles are involuntary and found only in the heart, contain large numbers of mitochondria making them resistant to fatigue, composed of branched striated fibers

Nervous Tissue

• Responsible for sensing stimuli and transmitting signals through the body

Neurons

• Dendrites receive signals from other neurons
• Cell body contains the nucleus and processes information
• Axons transmit signals to other neurons, muscles, or glands

Neuroglia

• Oligodendrocytes in the CNS and Schwann cells in the PNS surround axons and secrete myelin
• Myelin is a fatty insulating sheath that wraps around axons, increasing the speed of electrical impulses

Types of Neurons

• Sensory (afferent) neurons send sensory information from receptors to the CNS (brain/spinal cord), for example, touch sensors
• Motor (efferent) neurons send information from the CNS to muscles
• Interneurons relay signals between sensory and motor neurons within the CNS

Nervous System Structures

• Cranial nerves connect the brain to the periphery
• Spinal nerves connect the spinal cord to the periphery
• Tracts connect neurons in the spinal cord and brain

Organs and Organ Systems

• Organs are combinations of tissues that perform coordinated, complex tasks
• Organ systems consist of organs that function together

Major Organ Systems

• There are 11 major organ systems. Some of these are the Cardiovascular, Respiratory, Nervous, Skeletal, Muscular, Integumentary, Endocrine, Lymphatic, Digestive, Urinary, and Reproductive systems.
• The cardiovascular system includes the blood, heart, and blood vessels
• Functions of the Cardiovascular system: the heart pumps blood through blood vessels; blood transports O2 and nutrients to cells while removing CO2 and waste; and blood defends against disease and repairs damaged blood vessels

Urinary System

• Composed of kidneys, ureters, urinary bladder, and urethra
• Functions : produces, stores, and eliminates urine; eliminates waste; regulates blood volume and chemical composition; maintains the acid-base balance of body fluids; maintains the body's mineral balance; and regulates red blood cell production

Lymphatic System

• Composed of lymphatic fluid (lymph) and vessels, the spleen, thymus, lymph nodes, and tonsils
• Functions: returns proteins and fluid to blood; carries lipids from the gastrointestinal tract to blood and includes structures where lymphocytes that protect against disease-causing microbes mature and proliferate

Skeletal System

• Includes bones and joints of the body and their associated cartilages
• Functions: supports and protects the body, provides a surface area for muscle attachments, aids body movement, and stores minerals and lipids

Integumentary System

• Composed of skin and structures associated with it like hair, nails, sweat glands, and oil glands
• Functions: protects the body, helps regulate body temperature, eliminates some wastes, helps make vitamin D, and detects sensations such as touch, pain, warmth, and cold

Planes

• Frontal plane divides the body into front and back Mid-sagittal plane divides the body into left and right
• Transverse plane divides the body into top and bottom

Directions (Absolute)

• Anterior/Posterior means front vs. back
• Superior/Inferior means toward the head vs. toward the feet
• Medial/Lateral means toward the midline vs. away from the midline

Directions (Relative)

• Proximal/Distal means closer vs. farther from the attachment point
• Adduction/Abduction: movement to (ad) or away (abd) from the midline
• Flexion/Extension: decreasing vs. increasing the angle of a joint

Cardiovascular System

• Coronary artery disease involves narrowing or blockage of the coronary arteries
• Arrhythmias are heart rhythm problems

Functions of the Cardiovascular System

• Delivers nutrients, hormones, and signaling molecules
• Removes metabolic waste products from tissues
• Regulates body temperature

Blood Circulation

• The human body contains 5L of blood
• Every cell is within 100 μm of a blood vessel
• This proximity allows for diffusion of CO2, O2, and small solutes

Pulmonary and Systemic Circulation

• The right side of the heart moves deoxygenated blood to the lungs
• The left side of the heart moves oxygenated blood to the body

Circulatory Systems

• Pulmonary vessels transport blood to and from the lungs
• Systemic vessels transport blood to and from the body
• Arteries carry blood away from the heart
• Veins carry blood back to the heart
• The heart has 2 atria (left and right) to receive blood

Heart Chambers & Valves

• The heart has 2 ventricles (left and right) to pump blood
• One-way flow valves: tricuspid, pulmonary, mitral, and aortic

Systemic Circulation: Arterial

• The left ventricle ejects ~80ml (bolus) of blood into the aorta, the largest artery
• Blood flows into medium-sized arteries and arterioles, which branch from the aorta. Vessels further divide into capillaries

Vessel Structure

• From the heart to capillaries: Aorta → Arteries → Arterioles
• From capillaries to the heart: Venules → Veins → Vena Cava

Capillaries

• Slow blood flow allows for the exchange of nutrients, metabolic waste products, gases, hormones, etc., between tissue and blood

Systemic Circulation: Venous Return

• Deoxygenated blood collects in venules
• Venules lead to medium-sized, then large veins, then finally the vena cava (largest vein)
• Vena Cava delivers deoxygenated blood to the heart via the right atrium
• Blood is pushed back to the heart by muscle action on veins
• One-way valves in veins prevent backflow due to gravity

Systemic Circulation

• In going to smaller arteries, diameters and velocity decrease, but the overall area of the vascular bed increases

Cardiac Cycle

• Blood returns to the heart from circulation and collects in the atrium
• The atrium contracts and pushes blood into the ventricle
• The ventricle contracts, ejecting blood into circulation

Electrical Properties of the Cardiovascular System

• Heart tissue is made of two types of heart muscles: myocardial contractile cells (for heart contractions) and myocardial conductile cells (generate and spread electrical signals to control heartbeats, making up just 1%)
• Characteristics of Autoryhthmic Cells: self-excitable, don't require an external signal to fire an action potential, and have an unstable resting membrane potential, spontaneously depolarizing at a set rate
• Pacemaker Function: set rhythmic electrical excitation that stimulates heartbeat and the conduction system ensures coordinated contraction of atrial and ventricles
• Sinoatrial (SA) Node Functions: natural pacemaker containing autorhythmic cells that generates electrical impulse (action potential); ensures coordinated contraction; and signals travel 1m/s through muscle fibers
• Action potential is the rise and fall of electrical potential through the action of cellular membranes

Atrioventricular (AV) Node

• Located 1/10 of a second after the SA node generates an impulse, signalling to the AV node
• Functions: regulates ventricular contraction by delaying impulse, the only electrical link between atria and ventricles, and slows down the impulse, preventing ventricles from contracting too quickly
• Bundle of His is reached after passing through the AV node, transmitting signals through the cardiac muscles of both ventricles
• Spits into left and right bundle branches

Purkinje Fibers

• Specialized muscle cells with very fast conduction speeds Relay signals to the ventricular walls, ensuring ventricles to contract

Action Potential

• Describes the activity present in Contractile Cardiac cells
• Sodium and potassium pumps are primary active transport which maintains the membrane potential
• Describes the activity present in Autorhythmic Cardiac cells

Electrocardiogram (ECG)

• An electrocardiogram (ECG) monitors the electrical activity of cardiac muscles using the placement of electrodes to see when the ventricles fully depolarize
• P-Wave: created when the SA Node initiates the Atria to depolarize and contract
• There is an AV node delay period
• Ventricles depolarize, causing the QRS. Atria then repolarize
• Ventricles then fully repolarize causing the T wave
• Heart then Returns to a resting cycle
• P-wave is the atrial depolarization that can be initiated by the SA node
• Ventricular depolarization begins at the apex, causing the QRS complex and atrial repolarization occurs
• Ventricular repolarization then begins at the apex which then causes the Twave and finally it becomes complete again.
• ECGs aid in diagnosing arrythmias (irregular heart rhythms) such as tachycardia (fast), bradycardia (slow), and fibrillation (rapid, irregular)
• Issues in electrical conduction can be diagnosed as heart blocks Damaged heart muscle due to a lack of O2 is defined a myocardial infarction

Pacemakers & ICDs

• Pacemakers are used to treat bradycardia
• An implantable cardioverter-defibrillator (ICD) is used to treat the high risk of ventricular tachycardia or fibrillation
• The device detects irregular heart contractions and delivers an electrical impulse to restore rhythm

Cardiovascular System Thermodynamics

• Cardiac cycle has two phases: Diastole (ventricles relax and fill with blood) and Systole (ventricles contract and pump blood out)
• The healthy systolic blood pressure range is 90-120 and the healthy diastolic range is 60-80
• Ventricular filling: Ventricle relaxed with low pressure, Blood goes Atria Ventricle due to higher atrial pressure and AV values open to allow flow
• Atrial contraction: final push of blood into ventricle before the contraction at the end of diastole
• Ventricular contraction: start of systole, ventricular pressure rises to be greater than atrial, AV valves close to prevent backflow, semilunar valves (aortic and pulmonary) remain closed (Isovolumetric contraction) Ventricular ejection: ventricular pressure exceeds the pressure in the aorta and pulmonary arteries, forcing semilunar valves to open, blood ejected into circulation and at the end of systole Ventricular relaxation beginning of diastole: ventricular pressure drops, semilunar valves close, atrioventricular valves are closing resulting in isovolumetric relaxation and the volume increases again once that ventricular pressure reduces below the atrial pressure.

Phases of the Cardiac Cycle

• Phase 1: Inflow phase AB→BC is ventricular filling
• Phase 2: Isovolumetric contraction CD; pressure increases as volume stays the same
• Phase 3: Outflow phase DE, EF when the aortic wave opens so blood is exiting
• Phase 4: Isovolumetric relaxation FA: presure decreases while volume stays constant
• Systole takes place during phases CDEF, while diastole is during FABC

Cardiac Cycle

Hemodynamics Assumptions

• Neglects changes in kinetic and potential energy
• Adiabatic, isentropic, steady flow, steady state
• Variables shown in the cardiac cycle loop
• P2: systolic pressure
• P1: atrial filling pressure
• V2: end-diastolic volume
• Vi: end-systolic volume
• (V2-V1) is often referred to as the stroke volume (SV)
• A: inflow valve closes
• B: outflow valve opens

Estimations

To estimate power via this method Pumping Power (Pw=Wnet * h where h is the heart rate), Volumetric output from the left is needed which translates to the Cardiac Output = h * Stroke Volume and the Ejection Fraction which is found with the SV/EDV

Left Ventricle Heart Failure

Two distinctions:

• Systolic Dysfunction has been shown to have reduced the ejection fraction and enlarges the ventricle chamber
• Diastolic Dysfunction shows increased resistance for filling with an increase filling pressure which increases end-diastolic pressure and declines stroke stroke work. To combat failures, they use Left-Ventricular Assist Device LVADs which is a mechanical circulatory system for support with different end goals
• Bridge To Transplant option to aid in support
• Destination therapy choice when no other resolution is available.
• Bridge to recovery options in aiding the heart to recover.

Blood Rheology Summary

• Fluid Rheology: Compares fluids based on sheer stress vs. shear rate behaviors
• Non-Newtonian behavior, Newtonian behavior in how it interacts and the characteristics it portrays
• At 37 Degrees water is shown to approximately have .69cp and the other fluid at 1.16-1.35mPa
• Rheology of blood components like cells, erythrocytes, platelets (0.17) & then the cellular component 4.9% of components in blood

Rheology formulas

T = -m du/dy T = -m du/dy + Kc Y^ n T = K = 1/2

• Fluid properties like the yield stress and parameters protein dependencies
• Fibrinogen proteins shows interactions with the RBCs.
• If in a saline is present RBCs act as newtonian fluids.
• Hematocrits contributes with proportions of volume of the same.
• Fibrin and hematocrits have been deemed to contribute to the Non-Newtonian behavior.

Viscosity

• Viscosity's increases with the inclusion of hematocrits and are more affected by lower shear rate, smaller laminae
• RBCs are able to spin with the limited number laminae, allowing for better bullet formation.

Wall-Dependency

• Wall dependencies where the Axial accumulation is able to promote better circulation between cells to interact. With the presence of a the cell. There becomes a reduction in bullet shaped with viscosity decreases

Viscosity

• For Newtonian Fluids, Irratio is constant, z=
• For Non-Newtonian Fluids, Yr ratio changes