The Cardiovascular System and Blood Vessels

Define this:

• Transport blood throughout the body

• Maintain homeostasis within the body

• Providing adequate perfusion

Function of the Cardiovascular System

Define norepinephrine on BP:

Vasoconstrictor

Define this primary hormone:

Released from the posterior pituitary

Decreases urine output, increases blood volume via fluid intake

Only vasodilator in high doses

Antidiuretic

Define this primary hormone:

Released from the atrium of the heart in response to an increase in stretch of the atrial wall due to increased blood volume and venous return

Stimulates vasodilation, increase urine output, decreases blood volume

Atrial Natriuretic Peptide

Define this:

The specific amount of blood entering capillaries per unit time per gram of tissue

Perfusion

Define this:

Extend of blood vessel distribution within a tissue determines potential ability of blood delivery

Degree of Vascularization

Define this:

Carry blood away from the heart (mostly oxygenated)

Arteries

Define this:

Carry blood back to the heart (mostly deoxygenated)

Veins

Define this:

Sites of exchange such as gases

Capillaries

Define this:

This side of the heart receives deoxygenated blood and pumps it to lungs

Right side

Define this:

This side of the heart receives oxygenated blood and pumps it to body

Left side

Define this heart structure:

Superior chambers that receive blood and send it to ventricles

Atria

Define this heart structure:

Inferior chambers that pump blood away to the body via the pulmonary (right to lungs) and systemic circulation (left to body)

Ventricles

Define this heart structure:

Drain deoxygenated blood into right atrium

Superior Vena Cava and Inferior vena cava

Define this heart structure:

Transports blood from right ventricle
Splits into pulmonary arteries

Pulmonary Trunk

Define this heart structure:

Drain oxygenated blood into left atrium

Pulmonary Veins

Define this heart structure:

Transports blood from left ventricle

Aorta

What ensures unidirectional flow of blood through heart?

Valves

Define this heart structure:

Made up of three cusps and lies between right atria and ventricle

Tricuspid Valve

Define this heart structure:

made up of two cusps and lies between left atria and ventricle

Mitral Valve

Define this heart structure:

Anchor cusps of AV valves to papillary muscles that function to hold valve flaps in closed position

Prevent flaps from everting back into atria

Chordae tendineae

Define this heart structure;

Open and close in response to pressure changes

Prevent backflow from major arteries back into ventricles

Semilunar Valves

Which semilunar valve is located between right ventricle and pulmonary trunk?

Pulmonary Semilunar Valve

Which semilunar valve is located between left ventricle and aorta?

Aortic Semilunar Valve

Define this condition of the heart:

Blood backflows so heart repumps same blood over and over

Incompetent valve

Define this condition of the heart:

Stiff flaps that constrict opening

Heart needs to exert more force to pump blood

Valvular Stenosis

Define this circulation:

Right side receives oxygen-poor blood from tissues

Pumps blood to lungs to get rid of CO2

Pulmonary Circulation

Define this circulation:

Left side receives oxygenated blood from lungs

Pumps blood to body tissues

Systemic Circulation

Define this heart condition:

impaired ability of the heart to pump blood

Congestive Heart Failure

Define this heart condition:

May occur if right ventricle impaired

Additional fluid entering interstitial space

Systemic edema

Define this heart condition:

May occur if left ventricle improved

Swelling and fluid accumulation in the lungs

Pulmonary edema

How much does the heart weigh?

Less than 1 pound

Where is the heart located?

In mediastinum between lungs and second rib and fifth intercostal space

Define this:

Double-walled sac that surrounds heart

Pericardium

Define this:

Outermost layer and it attaches to diaphragm and base of aorta

Functions to protect and anchor heart to surrounding structures

Fibrous Pericardium

Define this layer:

Lines internal surface of fibrous pericardium

Parietal Layer

Define this layer:

On external surface of heart - attaches directly to the heart

Visceral Layer

Define this clinical condition:

Inflammation of the pericardium

Increased capillary permeability

Results in the heart unable to pump

Pericarditis

Define this:

Separates atra from ventricles

Groove extending around circumference of heart

Coronary sulcus

Define this:

Separate left from right ventricles

Grooves contains coronary vessels supplying blood to heart wall

Interventricular sulci

What has thicker walls the atria or ventricles? What side is thicker

Ventricles

Left ventricle thicker

Define this layer of the heart wall:

Visceral layer of serous pericardium

Epicardium

Define this layer of the heart wall:

Circular or spiral bundles of contractile cardiac muscle cells

Myocardium

Define this layer of the heart wall:

Innermost layer is continuous with endothelial lining of blood vessels

Endocardium

Define this:

Dense irregular tissue

Forms fibrous rings to anchor valves

Provides framework for attachment of cardiac muscles

Fibrous Skeleton

What separates left atrium from right atrium?

Interatrial Septum

What separates left ventricle from right ventricle?

Interventricular Septum

Define this:

Ridges on anterior wall and within auricle

Pectinate muscles

Define this:

Oval depression on interatrial septum

Occupies location of fetal foramen ovale

Fossa ovalis

Define this:

Receives deoxygenated blood from body

Right atrium

Define this:

returns blood from body regions above the
diaphragm

Superior vena cava

Define this:

returns blood from body regions below the
diaphragm

Inferior vena cava

Define this:

returns blood from coronary veins from the heart
• Blood will exit to right ventricle through right AV valve

Coronary Sinus

Define this:

Heart becomes enlarged

Causes High BP and coronary heart diseases

May result congestive heart failure

Cardiomegaly

Define this:

Inward growth of heart walls

Narrow opening for blood to pass through

Decrease CO

Hypertrophic Cardiomyopathy

Define this:

Transport oxygenated blood toward the heart wall or deoxygenated blood away from the heart wall

Coronary Circulation defined

Define this:

Travels within the coronary sulcus to supply the heart wall; branched directly off of the aorta

Right coronary artery

Define this:

Travels within the coronary sulcus to supply the heart wall; branches directly off of the aorta

Left Coronary Aorta

Define this:

Connections between arteries

Anastomoses

Define this:

Coronary blood flow to the heart wall is regulated by heart contraction

Blood Flow

Define this clinical condition:

Buildup of plaque

Coronary Spasm and narrowing of vessels

Coronary heart disease

Define this clinical condition:

Heart pain during strenuous activity

Usually on left side of chest, arm or jaw

Angina Pectoris

Define this clinical condition:

Sudden and complete occlusion of coronary artery

Weakness, shortness of breath, nausea, anxiety, and sweating

Myocardial Infarction

Define this:

mechanically join cells with protein filaments

Desmosomes

Define this:

Electrically join cells to make each heart chamber a functional unit

Gap Junctions

Define this:

Initiates and conduct electrical events to ensure proper timing of contractions

Heart depolarizes and contracts without nervous system stimulation

Conduction System

Define this:

Starts at medulla cardioinhibitory center

Decreases heart rate

Parasympathetic innervation

Define this:

Increases heart rate and force of contraction

Relayed via neurons from T1-T5 segments if spinal cord

Sympathetic innervation

Define this:

Respond to the spreading of the action potential along their sarcolemma. Promotes contraction of the muscle cells first w/ in the atria and then ventricles

Cardiac Muscle Cells

Define this:
Pacemaker cells that initiate the action potential thus regulating heartbeat

Na+/K+ pumps for maintaining the resting membrane potential

Nodal Cells

What is the resting membrane potential?

-60mV

Define this:

Reaching Threshold (Pacemaker potential):
• K+ channels are closed, but slow Na+ channels open and Na+ flows in,
causing interior to become more positive.
• Membrane potential changes from −60 mV to −40 mV (threshold value)
2. Depolarization:
• Fast voltage- gated Ca2+ channels open (around 40 mV), allowing huge
influx of Ca2+, leading to rising phase of action potential.
• Membrane potential changes from −40 mV to just above 0 mV
3. Repolarization:
• Ca++ channels close, voltage-gated K+ channels open, allowing efflux of
K+, and cell becomes more negative
• Membrane potential goes back to rest value (RMP = −60 mV)
• Voltage-gated Na+ channels open at −60 mV and process begins again

Action Potential

Define this:

Slowing of the heart rate and parasympathetic activity relayed by the vagus nerve

Vagal Tone

What is a difference between nodal cells and neurons?

Neurons require stimulation

How do regular neurons depolarize vs nodal (pacemaker) cells?

Neurons: Na⁺ influx causes depolarization

Nodal cells (SA/AV): Ca²⁺ influx causes depolarization

Why is the SA node the pacemaker of the heart?

• Depolarizes faster than any other cardiac tissue

• Intrinsic rate ≈ 75 beats/min

• Sets sinus rhythm

What is the function of the AV node delay?

Allows atria to contract and fill ventricles before ventricular contraction

List the intrinsic conduction pathway in order.

SA node → AV node → AV bundle → Bundle branches → Purkinje fibers

Define this:

Sustained contraction ensure efficient ejection of blood

Longer refractory period prevents tetanic contractions and allows chambers to fill with blood

Benefits of longer AP

A difference between cardiac cells and skeletal muscles?

Cardiac cells have a long refractory period

Define this:

Detect electrical currents generated by hearts

Electrocardiograph

Define this:

From atrial depolarization to beginning of ventricular
depolarization
Time to transmit action potential through entire conduction
system of P-wave to beginning of QRS deflection

P-R Interval

Define this:

Time from beginning of QRS to the end of T wave
• Reflects the time of ventricular action potentials
• Length depends upon heart rate
• Changes may result in tachyarrhythmia (rapid, irregular heart
rate)

Q-T interval

Define this:

Recorded as the P wave, muscle cells of atria stimulated to contract

Atrial depolarization

Define this:

Recorded as PQ segment muscle cells of atria construct and relax

Atrial Plaeau

Define this:

Not visible on ECG but occurs during QRS

Atrial Repolarization

Define this:

Recorded as QRS wave, muscle cells of ventricles stimulated to contract

Ventricular depolarization

Define this:

Recorded as ST segment muscle cells of ventricles contract and relax

Ventricular Plateau

Define this:

Recorded as T wave

Ventricular repolarization

Define this clinical condition:

Irregular heart rhythms

Homeostatic Imbalance

Arrhythmias

Define this clinical condition:

Rapid and irregular contractions

Homeostatic Imbalance

Fibrillation

Define this clinical condition:

Any abnormality in a heart electrical activity

Sometimes can be a heart block

Problems detected by enlarged r waves or prolonged Q-T intervals

Cardiac Arrhythmia

Define this clinical condition:

Slow conduction between atria and ventricles

First degree AV block

Define this clinical condition:

Failure of some atrial action potentials to reach ventricles

Second degree AV block

Define this clinical condition:

Failure of all action potentials to reach ventricles

Third degree AV block

Define this:

ll events in the heart from the start of one heartbeat to start of the next
• Atrial systole (contraction) and diastole (relaxation) are followed by ventricular
systole and diastole
• Cycle represents series of pressure and blood volume changes
• Mechanical events follow electrical events seen on ECG
• Contraction increases pressure; relaxation decreases it

Cardiac Cycle

Define this:

Contraction promotes increased ventricular pressure.
Increased pressure causes AV valves to be pushed closed and SL valves pushed
open. Both events move blood along one pathway and prevent backflow

Ventricular Contraction

Define this:

relaxation promotes decreased ventricular pressure.
Decreased pressure causes AV valves to be released and opened and SL valves
forced closed

Ventricular Relaxation

1. Atrial contraction and ventricular filling
   2. Isovolumetric contraction
   3. Ventricular ejection
   4. Isovolumetric relaxation

Phases of the cardiac cycle