Chapter 11: The Cardiovascular System

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121 terms · Essentials of Human Anatomy and Physiology, Elaine N. Marieb

Heart

Muscular pump that continually replaces the cell's surrounding environment so that waste can be removed and nutrients can be supplied.

Heart Characteristics

1. Size of a person's fist
2. beats and average of 72 times/minute (or 100,000 times/day)
3. Location in chest within a cavity called the mediastinum, also shifted to the left side.
4. Lower tip is the apex and it points to the left (patient's left), base is where the great vessels attach to the heart.

Pericardial Sac

Covering of the heart (pericardium)-loosely fitting, fluid producing sac covering the heart, yields a frictionless environment.

Fibrous pericardium

Outermost, tougher layer of the pericardium.

Serous pericardium

Fluid producing slippery membrane that forms a Pericardial space or cavity - located between epicardium and serous pericardium and contains fluid.

Parietal Pericardium

Outer layer of serous that forms part of pericardium.

Visceral Pericardium

Inner layer of the serous pericardium that is part of the heart wall (also called the epicardium).

Pericarditis

General inflammation of any part of the pericardium.

Cardiac Tamponade

Case of pericarditis in which excessive quantities of fluid actually hinder the beating of the heart - result in very low cardiac output.

Epicardium

Also called visceral pericardium outermost, somewhat thin covering (usually laden with fat), more fat means more effort of the heart to pump = more likelihood of heart attacks.

Myocardium

Cardiac muscle, thick layer of the heart.

Endocardium

Very thin, innermost lining of endothelium (same as the layer as the capillary).

Atria

Receive blood coming into the heart.

Ventricles

Eject blood from the heart.

Pulmonary circuit

Blood direction towards the lungs.

Systemic circuit

Blood direction through the rest of the body.

Mitral Valve or bicuspid

The left AV valve, consists of two flaps of endocardium.

Papillary Muscle

Small muscles within the heart that anchor the heart valves.

Chordae Tendineae / tendinous cords

Tiny white strings that anchor the flaps to the walls of the ventricles.

Tricuspid

The right AV valve, consist of three flaps.

Semilunar

Valves that act to stop blood flow back into the ventricles.

Atrioventricular valve

A term that includes mitral/bicuspid or tricuspid. Located between the atrial and ventricular chambers on each side. Prevent the backflow into the atria when the ventricles contract.

Prolapsed - incompetent valve

weakened valve, actually "leaks" results in heart repumping blood, decreases efficiency.

Stenosis

A narrowed valve that produces a detectable sound and causes the heart to work harder.

Coronary arteries

1. Blood supply to heart.
2.Two mains of these arteries left and right.
3. Branches off these main vessels are the circumflex and the anterior and posterior interventricular arteries.
4. Arise from the aorta just distal to the aortic vavle.

Angina or angina pectoris

Chest pain (spasms of the myocardium) due to temporary O2 deficiency)
Due to either stress induced spasms of coronary arteries or increased physical demands on the heart.

Referred pain

Pain of one region/area that is felt in another area. Classic location in addition to chest areas is left arm and occasionally neck and face.

Coronary (myocardial infarcation or MI)

1. Also called heart attack.
2. Death to tissue occurs due to extended lack of O2.
3. Caused by plaque buildup (arteriosclerosis) or clot formation.
4. Frequently described a crushing feeling in the chest, cold sweat, sense of doom/massive fear, nausea.
5. 1.5 million people have these a year, 1/3 die essentially immediately (within days), 1/2 will be dead within the year.
6. Symptoms of heart disease in 2/3 of males is usually heart attack or death in about 50% of females the first symptom is angina.

Bypass Surgery

Blocked or damaged blood vessel is "bypassed" by a replacement which is necessary to re-establish blood flow to cardiac tissue, blood flow to cardiac tissue, blood vessels used are taken fromt he leg or chest.

Balloon Angioplasty

A catheter with balloon a tip is inserted at site of blockage to press fatty deposit against artery wall, doesn't last long, good for weaker patients.

Stent

An expandable tube inserted into a blocked artery, excellent lifespan, done as an outpatient.

Properties of Cardiac Muscle

1. Striated
2. Lots of mitochondria
3. Intercalated disks/allows for cells to function as a unit, cells interlock

Intrinsic Innervation of the Heart

Conduction system of heart, ability of heart to contract (nerves not required); this system sets the basic rate of heartbeat.

Sinoatrial Node

"Pacemaker of the heart" located at the superior vena cava / right atrium junction.

Sinus rhythm

SA Node: Also called Intrinsic rhythm produced by these modified cardiac muscle cells (no nerve impulse necessary), sets pace, usually about 70-80 beats / min without nervous system (electrical charge). Average 72 beats/min.

Atrioventricular Node

1. Location in septum between two atria.
2. Function: picks up stimuli from SA node and carries to AV bundle or Bundle of His

AV Bundle or Bundle of His

1. Location- bundle of fibers that extend down interventricular septum
2. Function- conducts impulses to bundle branches

Bundle Branch

Basically smae as bundle of His, note location in the interventricular septum.

Purkinje fibers

Branches of bundle fibers that conduct impulses through muscles of both vertricles, contraction of the heart begins at the apex and spreads toward atria.

Arrhythmias

Irregular heart beats

Fibrillation

Rapid and irregular contractions, non-productive action (no blood pumped), fatal.

Defribrillation

Electric shock (wipes slate clean), helps to restore the regularity of beat, by depolarizing the entire heart then allowing it to restart.

Heart block

Damage to the AV node, essentially the entire conduction system is blocked and the ventricles must resort to contracting at an intrinsic rate which is a much slower rate.

Pacemaker

Artificial "pace setter" which takes care of the heart block problem; several types.

Extrinsic Innervation of the Heart

This system acts as both the brakes and accelerators of the heart.

Sympathetic Innervation

The autonomic nervous system. Increase the heart rate.

Cardioacceleratory center

Located in the medulla of the brainstem; stimulates the heart to increase its rate.

Parasympathetic Innervation

The autonomic nervous system- the vagus nerve (a cranial nerve) innervates the heart.

Cardioinhibitory Center

Located in the medulla; slows down the heart.

Electrocardiogram (ECG or EKG)

Measurements of electrical charges generated and transmitted by the heart, represents conduction (not contraction) that can be record and studies.

P wave

Movement of impulse (change of electrical charge) from SA Node through atrial muscles (contraction of both simultaneously), represents atrial depolarization.

QRS Complex

Depolarization of ventricles (contractions) spread of electrical impulses through ventricles (atria are relaxing but are masked).

T wave

Repolarization of ventricles (relaxation)

Cardiac cycle

All events associated with one heart beat.

Heart Sounds S1 or lubb

Atrioventricular valve (mitral & tricuspid) contraction.

Heart Sounds S2 or dubb

Semilunar valves closing (the second heart sound)

Murmurs

1. Unusual heart sounds.
2. Blood flows silently unless it is obstructed in which case it cause turbulence and sound.
3. Common in young children and some elderly
4. Valve status, must be checked and monitored.

Blood pressure

Systole/Distole
Normal 120/80

Systole

Pressure exerted by contraction of ventricles.

Diastole

Pressure exterted by relaxation of ventricles.

Atrial systoles

Contraction of the 2 atria.

Ventricular systoles

Contraction of the 2 ventricles.

Why do we need to control circulation?

1. Maintain blood movement.
2. Vary Volume and distribution pattern
3. Deliver oxygen and nutrients and carry waste away.

Cardiac output

1. Amount of blood pumped by each ventricle in one minute.
2. Cardiac output = stroke volume (amt of blood pumped in one contraction) x (# beats / minute) or (# of cardiac cycles).
3. CO=SV X HR

Cardiac tamponade

Condition in which the heart is compressed and critically low stroke volume results. May be caused by pericarditis.

Regulation of Stroke Volume- Frank Starling Law

1. Preload or the Frank-Starling Law of the Heart.
a. Amount the heart (ventricles) is stretched by contained blood.
b. Greater the stretch, greater the contraction
c. Venous return, volume in ventricles is determined by heart rate, exercise, and fluid loss.

Regulation of Stroke Volume-Heart Rate

a. Sympathetic division: epinephrine increase heart rate
b. Parasympathetic division: slows heart rate
c. Other factors: ions (electrolytes) (calcium and potassium in particular affect HR.
d. Age, gender, exercise, and body temperature.

Female Heart Rate

Average 72-80 beats/min

Male Heart Rate

Average 64-72 beats/min

Normal Range of heart rate

60-100 beats/min

Tachycardia

Heart rate over 100 beats/min

Bradycardia

Heart rate below 60 beats/min

Congestive Heart Failure /CHF

Pumping efficiency of the heart is so low that tissue needs are not met. TCan occur on either side of the heart, but weakness to one side stresses the other side. Typically a deteriorating condition due to :
a. athlerosclerosis (blockage) of coronary vessels.
b. persistent high BP
c. multiple MI's (heart attacks) hence death of tissue and replacement with scar tissue.
d. cardiomyopathy-stretched ventricles become flabby and muscle deteriorates.

Blood vessels

Form a closed loop delivery system that begins and ends at the heart. Although somewhat "pipe-like" they are actually quite unique because they can pulse, constrict, and even spread/grow into new areas. Quanity in body about 60,000 miles.

Types of Blood vessels

Arteries, capillaries, and veins.

Flow pattern of blood vessels

heart pumps>blood flows through arteries (larger than smaller then smallest)>capillaries>veins (smallest to larger to largest)>then back to the heart

Innermost layer

Layer of blood vessel, endothelium (one cell thick layer of simple squamous epithelium) next to the opening (lumen) of the vessel.

Middle layer

Layer of blood vessel, circular arranged smooth muscle and elastin fibers; this layer is usually thicker in arteries then veins; sympathetic nerve fibers control this muscle layer.

Outermost layer

Layer of the blood vessel, mostly loose connective tissue.

Artery

Carry blood away from the heart, carry oxygenated blood (except pulmonary).
1. Innermost layer-endothelium single cell thick.
2. Thicker walls.
3. Function: transportation, also resistance and blood pressure.

Vasoconstriction

Contraction of blood vessels. Relate to arteries not veins. Sympathetic nervous system.

Vasodilation

Relaxation of blood vessels. Relate to arteries not veins.
Parasympathetic nervous system.

Arteriole

Smallest artery, have only a few muscle cells wrapped around them. Major site of blood pressure regulation and blood flow to body parts.

Capillary

Microscopic, single cell thick layer, RBC's through one at a time.
1. Function: exchange site or point of diffusion of "food", "waste", and gases.
2. Estimated that every 2nd or 3rd cell is near a capillary although some tissues have more capillaries than others.

Precapillary sphincter

Surrounds the root of each true capillary and acts as a vavle to regulate the flow of blood into the capillary.

Capillary beds

Networks of capillaries that function almost as a unit.

Venules

Little veins

Veins

Blood flow is toward the heart, blood is deoxygenated (expect pulmonary). Function: transportation and reservoir can hold up to 65% of total blood volume.

Varicose veins

Excessively dialated veins usuallyin the lower legs, however in the anal area called hemorrhoids.

Vascular Anastomoses

Reconnection or alternate of blood vessels (either arteries or veins). Postive feature because it supplies alternate route to tissues thus ensuring their survival.

Circulation

To keep us alive, blood must be kept circulating. We are now aware the heart is a pump, the arteries are conduits (pipes), the arterioles are resistance vessels, the capillaries are exchage sites, and the veins are conduits and blood reservoirs.

Blood flow

Also called Cardiac output. Measured as volume flowing through a structure in a period of time.

Blood pressure

Force exerted (by blood) on the wall of a blood vessel, expressed in mm. of Hg. (mercury), loss of blood volume causes drop in blood pressure.

Peripheral resistance

Opposition to blood flow, the amount of friction encountered by blood as it flows through the vessels.

3 Factors of peripheral resistance

1. Blood viscosity
2. Blood vessel length-longer equals more friction
3. Blood vessel diameter-a flexible/changeable factor

Systemic Blood Pressure

When fluid is driven by a pump (the heart) thru a circuit of closed vessels, there is pressure. Blood flows from high to low pressure. Blood pressure changes when blood flow encounters resistance. BP is highest in the aorta and lowest in the vena cava as blood enters the heart.

Main Factor that influences BP

BP = CO x PR
Blood pressure = Cardiac Output x Peripheral Resistance

Neural Controls

1. Alter blood distibution to respond to specific demands.
2. Controlling blood vessel diameter to maintain adequate BP (Vasomoter Center of the medulla)

Baroreceptors

Pressure receptors in blood vessels (carotid artery and aorta)

Adrenal medulla

epinephrine and norepinephrine prepare for "fight or flight".

Antidiuretic hormone

helps to reestablish BP

Alcohol

promotes vasodilation (red-faced look); drop in BP

Kidneys or renal

Long term control of BP due to mechanism alter blood volume.

Pulse

Rhythmic expansion and recoil of arteries due to heart contraction, we equate it to the heart rate.

Pulse sites

1. Common carotid
2. Brachial
3. Radial
4. Femoral
5. Feet

Hypotension

Low tension pressure generally a systolic # of under 100 mm. Hg

Othrostatic hypotension

Dizziness due to sudden changes in posture (usually found in elderly), cause by slow nervous system response.

Chronic hypotension

Often due to nutrition (esp. Iron) Usually female.

Acute Hypotension

Sudden onset caused by circulatory shock. usually trama paitents.

Circulatory Shock

Inadequate blood volume and hence blood flow

Hypovolemic Shock

1. Lots of fluid loss, due to hemorrhage, burns, diarrhea, excessive vomiting.
2. Vasoconstriction results which returns BP to normal unless blood loss continues.

Vascular shock

Blood volume is normal, caused by extreme vasodilation perhaps due to septicemia (blood infection).

Hypertension

High blood pressure, defined as 140/90 consistently or higher.
1. 30% of people over 50
2. Can result in heart failure, vascular disease, renal failure, and stroke.
3. stresses heart wall, enlarges and becomes flabby
4. Accelerates athlersclerosis, blood vessel tears
5. no cure but lots of potential to control problem
6. known as silent killer

Factors of primary hypertension

90% have this type of hypertension.
Diet, Obesity, Age, Race, Heredity, Stress, Smoking

Blood Flow changes during exercise

1. Brain remains the same.
2. Muscle lots more with exercise
3. Skin some additional with exercise
4. Abdomen less with exercise

coronary artery disease

Fatty, calcified deposits in heart blood vessels.

aneurysm

a balloon like out pocketing of the artery wall, places an artery at risk for rupture, may be congenital (birth defect) but more likely due to hypertension or athlersclerosis, likely sites include aorta, and arteries in brain.

angiogram

Diagnostic technique using radiopaque dye to show blood vessel blockage/damage.

phlebitis

Inflammation of a vein with associated pain, throbbing, and redness of the skin over the inflamed area, usually cause by bacterial infection.

thrombophlebitis

Intravascular clotting often follwoing phlebitis; particulary dangerous if clots become detached and form an embolus.

arteriosclerosis

Hardening of the arteries-changes in the elasticity of blood vessels.

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