CARDIOVASCULAR CARDIOVASCULAR SYSTEMSYSTEM

Chapter 11Chapter 11

CIRCULATORY SYSTEM-CIRCULATORY SYSTEM-2 interconnected circuits 2 interconnected circuits

connected at the heart; connected at the heart; also contains arteries, also contains arteries, capillaries, veins, and capillaries, veins, and bloodblood

Used to transport Used to transport oxygen, nutrients, oxygen, nutrients, wastes, hormones etc.wastes, hormones etc.

1. SYSTEMIC CIRCUIT- 1. SYSTEMIC CIRCUIT- exits the LEFT side of exits the LEFT side of heart and travels to heart and travels to BODY (hi O2)BODY (hi O2)2. PULMONARY 2. PULMONARY CIRCUIT – exits the CIRCUIT – exits the RIGHT side of the heart RIGHT side of the heart and travels to LUNGS and travels to LUNGS (low O2)(low O2)

HEARTHEART

- size of a persons fist- size of a persons fist - 4 chambers- 4 chambers

- 2/3 of the heart lies to the - 2/3 of the heart lies to the left of the sternum left of the sternum

APEXAPEX- points to the left hip and - points to the left hip and is lies on the diaphragmis lies on the diaphragm

BASEBASE- where blood vessels - where blood vessels emerge- point toward the emerge- point toward the right shoulder and lies right shoulder and lies beneath second ribbeneath second rib

MEDIASTINUM- MEDIASTINUM- opening opening between the lungsbetween the lungs

HEART WALL- 3 LAYERSHEART WALL- 3 LAYERS

1.1. ENDOCARDIUM- (white) inner ENDOCARDIUM- (white) inner most layer- slick decreasing friction most layer- slick decreasing friction to allow blood flow to allow blood flow

22 MYOCARDIUM-- thick cardiac MYOCARDIUM-- thick cardiac muscle-muscle-

3.3. EPICARDIUM (visceral EPICARDIUM (visceral pericardium)- slick outer covering pericardium)- slick outer covering which decreases friction on the heartwhich decreases friction on the heart

PERICARDIUM-PERICARDIUM-

-double layered sac that gives heart room to -double layered sac that gives heart room to move, but resists over-expansionmove, but resists over-expansion

1. VISCERAL PERICARDIUM lines the 1. VISCERAL PERICARDIUM lines the outside of the heartoutside of the heart

2. PARIETAL PERICARDIUM- protects heart 2. PARIETAL PERICARDIUM- protects heart and anchors it to diaphragmand anchors it to diaphragm

3. PERICARDIAL FLUID-3. PERICARDIAL FLUID- Serous fluid- Serous fluid- which reduces friction found in the which reduces friction found in the PERICARDIAL CAVITY (space between the PERICARDIAL CAVITY (space between the layers)layers)

HEART CHAMBERS (4 TOTAL)HEART CHAMBERS (4 TOTAL)

LEFT AND RIGHT ATRIA (atrium sing.) LEFT AND RIGHT ATRIA (atrium sing.) -Located superior-Located superior-smaller and less muscular-smaller and less muscular -atrial contraction forces blood into -atrial contraction forces blood into

ventriclesventricles- receive return blood flow from:- receive return blood flow from:

1.1. SYSTEMIC CIRCUIT- dumps into right SYSTEMIC CIRCUIT- dumps into right atriumatrium

2. 2. PULMONARY CIRCUIT- dumps into left PULMONARY CIRCUIT- dumps into left atriumatrium

--

LEFT AND RIGHT VENTRICLESLEFT AND RIGHT VENTRICLES- located inferiorlocated inferior- Much larger and more Much larger and more

musclemuscle

- receive blood from atria- receive blood from atria

- contract to send blood - contract to send blood out:out:

LEFT VENTRICLE- OUT LEFT VENTRICLE- OUT to systemic circuitto systemic circuit

RIGHT VENTRICLE- OUT RIGHT VENTRICLE- OUT to pulmonary circuitto pulmonary circuit

FEATURES OF THE HEARTFEATURES OF THE HEART

INTERVENTRICULAR INTERVENTRICULAR SEPTUMSEPTUM- thick muscle - thick muscle (myocardium) that (myocardium) that divides ventriclesdivides ventricles

INTERVENTRICULAR INTERVENTRICULAR SULCUSSULCUS- line on outside - line on outside that divides ventriclesthat divides ventricles

INTERATRIAL SEPTUM-INTERATRIAL SEPTUM- muscle that divides atriamuscle that divides atria

INTERATRIAL SULCUSINTERATRIAL SULCUS- line - line on outside that divides on outside that divides atriaatria

FEATURES OF THE HEARTFEATURES OF THE HEART

ATRIOVENTRICULAR SULCUSATRIOVENTRICULAR SULCUS- line on - line on surface of heart that separates atria surface of heart that separates atria from ventriclesfrom ventricles

ATRIOVENTRICULAR VALVESATRIOVENTRICULAR VALVES- (AV - (AV valves) valves between the atria and valves) valves between the atria and ventriclesventricles

ATRIOVENTRICULAR VALVESATRIOVENTRICULAR VALVES--BICUSPID BICUSPID (2) – located on (2) – located on

left side (blood returned left side (blood returned from lungs)from lungs)

TRICUSPIDTRICUSPID (3)- located on (3)- located on right side ( blood right side ( blood returned from body)returned from body)

CHORDAE TENDINAECHORDAE TENDINAE- thin - thin strands of connective strands of connective tissue that allow valves tissue that allow valves to close during to close during ventricular contraction- ventricular contraction- prevents backflow of prevents backflow of blood to the atriablood to the atria

SEMILUNAR VALVESSEMILUNAR VALVES--

valves leaving the ventricles- each has 3 valves leaving the ventricles- each has 3 cusps which close tightly until contraction cusps which close tightly until contraction by the ventricles forces them openby the ventricles forces them open

AORTIC SEMILUNAR VALVEAORTIC SEMILUNAR VALVE- leads to aorta - leads to aorta and systemic circuitand systemic circuit

PULMONARY SEMILUNAR VALVEPULMONARY SEMILUNAR VALVE- leads to - leads to pulmonary artery and pulmonary circuitpulmonary artery and pulmonary circuit

SYSTEMSSYSTEMS

ARTERIESARTERIES- blood vessels going away - blood vessels going away from the heartfrom the heart

VEINSVEINS- blood vessels going toward - blood vessels going toward the heartthe heart

Major VeinsMajor Veins

SUPERIOR VENA CAVA- enters the top SUPERIOR VENA CAVA- enters the top of the right atriumof the right atrium

INFERIOR VENA CAVA- enters the INFERIOR VENA CAVA- enters the bottom of the right atriumbottom of the right atrium

PULMONARY VEIN- enters the left PULMONARY VEIN- enters the left atriumatrium

MAJOR ARTERIESMAJOR ARTERIES

AORTA- exits the left ventricle has AORTA- exits the left ventricle has large curve (AORTIC ARCH)large curve (AORTIC ARCH)

PULMONARY ARTERY- exits right PULMONARY ARTERY- exits right ventricle and branches under aortic ventricle and branches under aortic arch to each lungarch to each lung

CIRCULATION THROUGH THE CIRCULATION THROUGH THE HEARTHEART

Beginning in the right atrium trace a drop of Beginning in the right atrium trace a drop of blood through the pulmonary circuit , back to the blood through the pulmonary circuit , back to the heart and out the aorta. Identify where it is heart and out the aorta. Identify where it is oxygenated and deoxygenated. oxygenated and deoxygenated.

1. _1. _Right atrium (deoxygenated Right atrium (deoxygenated 7.____________7.____________2.2. _____________________8._______________________________________8.__________________3.__________________________9.__________________3.__________________________9.__________________4.__________________________10.________________4.__________________________10.________________5.__________________________11.5.__________________________11.Aorta (oxygenated)_Aorta (oxygenated)_6.__________________________6.__________________________

STRUCTURE OF BLOOD VESSELSSTRUCTURE OF BLOOD VESSELS

ARTERIESARTERIES ARTERIOLES ARTERIOLESCAPILLARIESCAPILLARIESVENULESVENULES VEINSVEINS

WALLS OF BLOOD VESSELS HAVE 3 LAYERS (except WALLS OF BLOOD VESSELS HAVE 3 LAYERS (except capillaries)- that surround the LUMEN (opening)capillaries)- that surround the LUMEN (opening)1.1. TUNICA INTERNA- innermost (one cell thick) TUNICA INTERNA- innermost (one cell thick) slick surfaceslick surface2.2. TUNICA MEDIA-bulky, middle coat of TUNICA MEDIA-bulky, middle coat of smooth musclesmooth muscle3.3. TUNICA EXTERNA- outermost composed of TUNICA EXTERNA- outermost composed of fibrous connective tissue fibrous connective tissue ; supports and ; supports and protects the blood vesselsprotects the blood vessels

DIFFERENCES BETWEEN VEINS DIFFERENCES BETWEEN VEINS AND ARTERIESAND ARTERIES

1. Walls of arteries are much thicker 1. Walls of arteries are much thicker than veinsthan veins

- much more tunica media- much more tunica media

-needs to be able to expand and -needs to be able to expand and contractcontract

- if near the heart will have hi blood - if near the heart will have hi blood pressurepressure

DIFFERENCES BETWEEN VEINS DIFFERENCES BETWEEN VEINS AND ARTERIESAND ARTERIES

2.2. Veins have much larger lumen and very Veins have much larger lumen and very little tunica medialittle tunica media

- away from the heart will have low blood - away from the heart will have low blood pressure (no need to expand)pressure (no need to expand)

-skeletal muscle aides in helping blood -skeletal muscle aides in helping blood return by contracting the veinsreturn by contracting the veins

- larger veins have venous valves that close larger veins have venous valves that close preventing backflow due to gravitypreventing backflow due to gravity

VARICOSE VEINS-VARICOSE VEINS- veins inefficient in blood veins inefficient in blood return- blood poolsreturn- blood pools

CAPILLARIES AND CAPILLARY CAPILLARIES AND CAPILLARY BEDS (pg 342)BEDS (pg 342)

CAPILLARY- have only 1 layer of cells CAPILLARY- have only 1 layer of cells (TUNICA INTERNA)(TUNICA INTERNA)

- thin walls permit the exchange of - thin walls permit the exchange of materials between the blood and materials between the blood and interstitial fluidinterstitial fluid

CAPILLARY BEDS-CAPILLARY BEDS-

networks of tiny capillaries intertwined networks of tiny capillaries intertwined that typically that typically contains 2 types of contains 2 types of vessels (1 vascular shunt and 10-100 vessels (1 vascular shunt and 10-100 true capillaries)true capillaries)

VASCULAR SHUNT- vessel that directly VASCULAR SHUNT- vessel that directly connects arterioles and venules-connects arterioles and venules-precapillary sphincters will close and precapillary sphincters will close and direct the blood straight to venules direct the blood straight to venules when needed (cold)when needed (cold)

CAPILLARY BEDS-CAPILLARY BEDS-

TRUE CAPILLARIES- when precapillary TRUE CAPILLARIES- when precapillary sphincters are open blood will take sphincters are open blood will take part in exchange with local cell tissuepart in exchange with local cell tissue

- CAPILLARIES are the only type - CAPILLARIES are the only type of blood vessel that can redirect of blood vessel that can redirect bloodflowbloodflow

CARDIAC CYCLE

CARDIAC CYCLE- one complete series of heart contractions which constitutes a single heartbeat.

CARDIAC CYCLE

The heart beats in a rhythmic “Lub-Dub” due to the coordinated contractions of both atria and both ventricles.

Heart sounds are produced by the closing of heart valves !!!!

ATRIAL CONTRACTION increases the pressure and forces blood into the Ventricles ( which are relaxed at that time)

CARDIAC CYCLE

VENTRICULAR CONTRACTION- increases pressure forcing the atrioventricular valves closed preventing backflow to atria (Lub sound) while also forcing the semilunar valves open to allow blood to arteries

VENTRICULAR RELAXATION allows semilunar valves to close to prevent backflow into the ventricles (Dub sound)

Heart Electrical Conduction System-

Cardiac cells have an inherent ability to contract in a rhythmic manner. Specific pace-setting cardiac cells can send out electrical signals to adjacent cells causing simultaneous contraction.

Heart Electrical Conduction System-

SINOATRIAL NODE- (SA NODE) group of PACEMAKER cells located in the wall of the right atrium which set the pace for the entire cardiac cycle. They send out impulses to both atria to allow cause them to contract.

ATRIOVENTRICULAR NODE (AV NODE)- group of cells located in the inferior part of the right atrium near the interatrial septum which receive impulses from the SA NODE pause for a while to allow the atria to empty and then send the impules down to the ventricles via the ATRIOVENTRICULAR BUNDLE (Bundles of His) and the PURKINJE FIBERS

Heart Electrical Conduction System-

ATRIOVENTRICULAR BUNDLE- special muscle fibers located in the interventricular septum which pass the electrical signal down to the Purkinje fibers and cause the ventricles to contract simultaneously.

PURKINJE FIBERS- located at the APEX of the heart and expands up the outer walls of each ventricle cause the simultaneous contraction.

Heart Electrical Conduction System-

ELECTROCARDIOGRAM- measures the electrical events that occur during a cardiac cycle

P WAVE - Sino atrial node firing- (then a pause)

QRS COMPLEX- AV bundle and Purkinje fibers fire (much larger amount of electricity needed)

T WAVE- ventricles repolarizing (atria depolarize during QRS so it is masked)

BLOOD PRESSURE

BLOOD PRESSURE- the primary force that pushes blood through arteries and arterioles.

It is influenced by cardiac output, peripheral resistance and blood volume. Blood pressure is regulated by the nervous system, hormones, and kidneys.

FINDING BLOOD PRESSUREFINDING BLOOD PRESSURESPHYGMOMANOMETER- blood pressure cuff which is wrapped

around the arm and finds the pressure on the BRACHIAL ARTERY. How to use a sphygmomanometer along with a stethoscope to find blood pressure1. Pump up the cuff so that the artery becomes compressed and blood can not pass through.

2. Slowly open the release valve allowing cuff pressure to drop.

3.Using a stethoscope listen below the cuff for the first sounds of blood squeezing through the cuff. When you hear a tapping sound this is the SYSTOLIC PRESSURE.

4.Allow pressure to decrease until no tapping sound is heard. The moment it becomes inaudible is the DIASTOLIC PRESSURE.

Factors affecting Blood pressure

1. PERIPHERAL RESISTANCE- the friction of blood rubbing against the vessels. Peripheral resistance is affected by the viscosity of the blood and the size of the lumen (opening)

2. BLOOD VOLUME- (about 5 liters) - When blood volume or blood pressure rises the kidneys respond by removing more water from the body as urine. When blood pressure is low kidneys reduce the amount of urine produced.

3. CARDIAC OUTPUT-

CARDIAC OUTPUT = Heart rate x Stroke Volume

The average heart rate at rest is 75 beats/minute and the average stroke volume is 70 mL per beat

STROKE VOLUME- volume of blood ejected by the contraction of ventricles.

CARDIAC OUTPUT

MEDULLA OBLONGATA (of the brain) - controls the cardiac cycle by sending signals to the SINOATRIAL NODE

ARTERIAL BLOOD PRESSURE- SYSTOLIC PRESSURE (typically 120 mmHg).-highest value when ventricles contract DIASTOLIC PRESSURE (typically 70-80 mmHg) lowest value when ventricles are relaxed

Factors affecting Blood pressure

4. NERVOUS SYSTEM- VASOCONSTRICTION- making the arteries

smaller- if blood pressure levels are too low or oxygen levels are too low

VASODILATION- opening up the arteries

5. HORMONAL CONTROLS-EPINEPHRINE and NOREPINEPHRINE- produced by adrenal glands in fight or flight- increases cardiac output and constricts blood vessels

Drugs which increase blood pressure- antidiuretics and nicotine ANTIDIURETIC- stimulates kidneys to conserve water