Ch7: Cardiovascular System

Cardiovascular System Components

Heart, blood vessels, blood

Heart

Cardiac muscle

2 pumps

Heart: Right Side

Pulmonary circulation pump

Deoxygenated blood from body to lungs (pulmonary arteries)

Heart: Left Side

Systemic circulation pump

Oxygenated blood from lungs (pulmonary veins) to body (aorta)

More muscular (stronger pumping)

Heart: Atria

Receive blood from venae cava (right) or pulmonary veins (left)

Contract to push blood into ventricles

Heart: Ventricle

Receive blood from atria

Contract to push blood to lungs (right) or systemic circulation (left)

More muscular than atria (powerful contractions)

Heart Valves

Create pressure to propel blood

Prevent backflow

Heart: Atrioventricular Valves

Separate atria and ventricles

Atrioventricular: Tricuspid Valve

Between right atrium and ventricle

3 leaflets

Atrioventricular: Bicuspid/Mitral Valve

Between left atrium and ventricle

2 leaflets

Heart: Semilunar Valves

Separate ventricles and vasculature

Semilunar: Pulmonary Valve

Between right ventricle and pulmonary circulation

3 leaflets

Semilunar: Aortic Valve

Between left ventricle and aorta

3 leaflets

Heart Electrical Conduction Pathway

1. Sinoatrial (SA) node
2. Atrioventricular (AV) node
3. Bundle of His (AV bundle)
4. Purkinje fibers

Electrical Conduction 1: SA Node

Intrinsic impulse initiation from cells in right atrium

Depolarization causes atrial systole (contraction)

Electrical Conduction 2: Atrial Systole

Increase atrial pressure

Force additional blood (atrial kick) into passively-filling ventricles

Electrical Conduction 3: AV Node

Between atria and ventricles

Signal delay allow complete ventricular filling

Electrical Conduction 4: Bundle of His

In interventricular septum

Electrical Conduction 5: Purkinje Fibres

Distribute electrical signal through ventricular muscle

Intercalated discs containing gap junctions coordinate ventricular contraction

Heart Beat

60-100 bpm (SA node)

Athletes: Lower

Stress and Excitement: Higher

Autonomic Control

Sympathetic: Increase heart rate, cardiac muscle contractility, cardiac output

Parasympathetic (Vagus Nerve): Decrease heart rate, output

ECG: Electrical Spikes

Before contractions

ECG: P-Wave

Before atrial systole

ECG: QRS Complex

Before ventricular systole

ECG: T-Wave

Ventricular repolarization

Heartbeat: Systole

Ventricular contraction (increase pressure)

AV valves close

Blood pump out of ventricle

Heartbeat: Diastole

Ventricular relaxation (decrease pressure)

Semilunar valves close

Blood from atria fill ventricles

Diastolic Pressure

Elastic artery walls stretch to receive blood

Maintain pressure during ventricular diastole

Heart Sounds: S1

First sound

AV valves close

Heart Sounds: S2

Second sound

Semilunar valves close

Heart Sounds: S3 and S4

Extra sounds

Heart muscle stiffness or high bp

Cardiac Output (CO)

Total blood volume pumped by ventricle in 1 minute (same amount in both)

Ventricular Tachycardia

Fast ventricular contraction

Decrease ventricular relaxation and filling

Pump less blood

Arteries

Carry blood away from heart (mostly oxygenated)

Aorta → Arteries → Arterioles → Capillaries

Arteries: Deoxygenated Blood

Pulmonary and umbilical arteries

Arteries: Walls

Thick, muscular, elastic

Resist blood flow (left heart generate more pressure to overcome)

More smooth muscle = Recoil maintain high pressure and force blood forward

Capillaries

1 endothelial cell layer

Easy diffusion

Gas and solute exchange with tissues

Bruising

Damaged capillaries allow blood to enter interstitial space

Veins

Carry blood to heart (mostly deoxygenated)

Capillaries → Venules → Veins → Superior and inferior vena cava

Veins: Oxygenated Blood

Pulmonary and umbilical veins

Veins: Walls

Thin and inelastic

Less smooth muscle = less recoil

Stretch to hold more blood (carry more blood than arteries)

Veins: Increased Pressure

Blood entering vena cava in vertical column

Work against gravity

Veins: Valves

Push blood forward (against gravity) and prevent backflow

Veins: Skeletal Muscle

Surround and squeeze veins during contraction

Varicose Veins

Valve failure cause blood pooling to distend veins

Blood Clots

From long periods of inactivity

Blood pooling in deep veins forms deep vein thrombosis

Pulmonary Embolus: Blood clot travel to lungs

Blood Vessels: Endothelial Cells

Line blood vessels

Release chemicals for vasodilation, vasoconstriction, blood clot formation

Allow WBC passage

Myocardial Infarction

Lack of bloodflow to coronary arteries decreases O2 delivery and causes muscle tissue death

Myocardial Infarction: b-Blocker

Inhibit sympathetic stimulation to decrease heart rate and contractility

Decrease O2 demand

Circulation

Superior/Inferior vena cava → Right atrium → Tricuspid valve → Right ventricle → Pulmonary valve → Pulmonary artery → Lungs → Pulmonary veins → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Arteries → Arterioles → Capillaries **(usually 1 capillary bed)** → Venules → Veins

Circulation: Portal System

Blood pass through 2 capillary beds in series

Hepatic Portal System

Gut capillaries → Hepatic portal vein → Liver capillaries

Hypophyseal Portal System

Hypothalamus capillaries → Anterior pituitary capillaries (release hormones)

Renal Portal System

Glomerulus → Efferent arteriole → Vasa recta

Blood Composition

55% liquid

45% cells

Blood: Plasma

Liquid portion

Contain nutrients, salts, gases, hormones, proteins

Plasma → Serum

Remove clotting factors

Blood: Cells

Erythrocytes, leukocytes, platelets

Formed from hematopoietic stem cells

Erythrocytes (RBC)

Contain hemoglobin to bind 4 nonpolar O2 for transportation

Erythrocytes: Biconcave

Indent on sides

Assist in travelling through capillaries

Increase cell SA and gas exchange

Erythrocytes: Organelles

Lost after maturation

Space for hemoglobin

No mitochondria = no O2 consumption

No nucleus = no mitosis (Liver and spleen cells phagocytize to recycle)

Complete Blood Count: Hemoglobin Concentration

Measure quantity of hemoglobin in blood

g/dL

Complete Blood Count: Hematocrit

Measure RBC % of blood sample

Leukocytes (WBC)

Leukocyte Classes

Granulocytes and agranulocytes

Leukocytes: Granulocytes

Neutrophils, eosinophils, basophils

Contain cytoplasmic granules with toxic compounds (released via exocytosis)

Nonspecific immunity

Leukocytes: Agranulocytes

Lymphocytes, monocytes

No granules

Specific immunity

Primary infection response and immune memory

Agranulocyte: B-Cell

Lymphocyte

Mature in bone marrow

Generate antibodies

Agranulocyte: T-Cell

Lymphocyte

Mature in thymus

Kill infected cells

Activate other immune cells

Agranulocyte: Monocyte

Phagocytose foreign material

Leave bloodstream → Macrophage

Macrophage: CNS

Microglia

Macrophage: Skin

Langerhans cells

Macrophage: Bone

Osteoclasts

Thrombocytes (Platelets)

Cell fragments released from megakaryocytes (bone marrow)

Assist blood clotting

Hematopoiesis

Blood cell and platelet production

Hormone, growth factor, and cytokine induced

Hematopoietic Hormones: Erythropoietin

Secreted by kidney

RBC development

Hematopoietic Hormones: Throbopoietin

Secreted by liver and kidney

Stimulate platelet development

Antigens

Blood cell surface proteins

Specific target for immune system reaction

ABO antigens and Rh factor

Antigens: ABO Antigens

3 alleles for blood type

A and B: Codominant (express 1, both, or none)

O: Recessive

ABO Antigens: Type A Blood

IAIA or IAi

Produce A antigens

Produce anti-B antibodies

ABO Antigens: Type B Blood

IBIB or IBi

Produce B antigens

Produce anti-A antibodies

ABO Antigens: Type AB Blood

IAIB

Produce A and B antigens

Produce no antibodies

Universal recipients

ABO Antigens: Type O Blood

ii

Produce no antigens

Produce anti-A and anti-B antibodies

Universal donors

Blood Type in Transfusions

Hemolysis if donor blood antigen recognized as foreign by recipient immune system

Antigens: Rh Factor

RBC surface protein from D allele

Rh+: D present, dominant

Rh-: D absent, recessive

Rh Factor: Anti-Rh Antibodies

Produced by Rh- individual after exposure to Rh+ blood

Rh Factor: Erythroblastosis Fetalis

Rh- mother produce anti-Rh+ antibodies after exposure to Rh+ fetus blood

Subsequent pregnancies with Rh+ fetus cause anti-Rh antibodies to cross placenta

Blood Pressure (BP)

Force/area exerted on blood vessel walls by blood

Systolic/diastolic pressure (90/60 - 120/80)

BP: Sphygomomanometer

Measure gauge pressure in systemic circulation

BP: Atrial → Venous Circulation

Largest drop across arterioles (protect thin-walled capillaries)

Hypertension

High bp

Damage blood vessels and organs

Pressure Gradient

Drive CO against total peripheral resistance (TPR) from arterioles and capillaries

TPR

Resist blood flow

TPR: Increase Length

Increase TPR

TPR: Increase Cross-Sectional Area

Decrease TPR

TPR: Increase Open Capillary Beds in Parallel

Decrease TPR

BP: Baroreceptors

Neurons detecting mechanical force changes on blood vessel walls

Increase BP: Baroreceptor Reflex

Stimulate sympathetic NS → Vasoconstriction → Increase BP

Increase BP: Chemoreceptor Reflex

Detect high blood osmolarity → ADH release → Increase water reabsorption → Increase BP and volume

Increase BP: Juxtaglomerular Cells

Low perfusion (kidney) → Aldosterone release through renin-angiotensin-aldosterone system → Increase Na+ and water reabsorption → Increase BP and volume