RSP 2230: The Cardiovascular System

Blood flow through the heart:

Body → SVC/IVC → Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonic Valve → Pulmonary Arteries → Lungs → Pulmonary Veins → Left Atrium → Mitral Valve → Left Ventricle → Aortic Valve → Aorta → Body

Blood:

Blood: 8% of total weight

• Plasma

• Erythrocytes (RBCs)

• Leukocytes (WBCs)

• Platelets

Erythrocytes (RBCs):

• Primary function:

- Transport O2 and CO2

• Hematocrit:

- Percent of RBC’s to total blood volume

- Normal = 42-45

• Produced in the red bone marrow

- Destroyed in spleen & liver

• Hemoglobin (transports O2 from lungs ➡ tissues & gives red blood color)

- MAJOR component

Leukocytes (WBCs):

• Purpose - Protects body against invaders = removes waste

• Normal levels: 4,000-11,000

• Ordered as “CBC w/ Diff” - most frequently ordered blood test!

• Differential - NEVER LET MONKEYS EAT BANANAS

Neutrophils - first responders, rush to bacteria, act like an antibiotic LIKE protein, 65-70% of granulytes

Lymphocytes - lymph nodes —> filtering station, swell when there’s infection, t-cells tumors & viruses, b-cells make antibodies and act like memory cells…

Monocytes - macrophage properties —> eat viruses + bacteria, clean up dead cell debris, ⬆ if infection is present

Eosinophils - ewwwww parasite eating, allergic reaction, decreases severity of allergies, pts will have higher eosinophils

Basophils - cause allergic responses, release granules that release histamines, causes vasodilation in body, and vasoconstriction in the lungs ➡ which is WHY YOU TAKE ANTI HISTAMINES

Granulocytes:

• Neutrophils (65-75%)

- Antibiotic-like proteins - eat/phagocytic bacteria

• Eosinophils - kills parasitic worms

- ⬇ Severity of allergies (asthmatics have ⬆ levels)

• Basophils - Allergy response - less than 1%

- contains histamine - inflammatory substance

releases histamine - contain heparin: anticoagulant

• Histamine

• Causes vasodilation

• What does histamine cause to happen in the lung? ➡ Broncoconstricts!

Agranulocytes:

• Lymphocytes - lymph nodes

- Purpose? ➡ Immunity

- T cells - viruses & tumors

- B cells - antibodies (produces antibodies)

• Monocytes 4-8% of WBC

- Macrophages - viruses & bacteria

- Chronic infections = ⬆ monocytes

- Viruses & parasites

Thrombocytes:

• Platelets

- Normal level - 250,000 - 500,000

- Function? ➡ prevents blood loss, blood clots

• Plasma

- 55% of total blood volume

- Most made out of: tiny cell pieces

- Blood serum = plasma - clotting factors

Plasma:

⭐️ 10% is composed of:

• Proteins

• Electrolytes

• Food substances

• Respiratory gases: PO2, PCO2

• Hormones

• Vitamins

• Waste products

SERUM = plasma - clotting factors

Heart-Gross Anatomy:

• Location & size: 4 chambers

• Apex - bottom: 5th intercostal space

• Base - top: above 2nd rib

• Assessment of size: chest x rays

• Pericardium: loose membrane that covers heart, sac

• Myocardium: heart muscle, middle

• Endocardium: lines heart chambers

• Epicardium: OUTER layer, protective layer

Mediastenum - where heart is, behind sternum

Clinical Connections:

• Pulse Paradoxus:

- Pulse lost during inspiration - possible brief drop in BP less than 10 mmHg in systolic pressure - hypovolemic shock

- Found in asthma exacerbations

• Cardiac Tamponade:

- Blood in the pericardial sac - blood fills in the sac, left ventri cannot pump! —> could go into MI —> heart muscle tear, contractility

• Pericardiocentesis

- Removal of fluid pericarium - tx to remove/drain fluid, 14G needle

Heart Gross Anatomy:

• Heart Chambers:

- Atria - upper chambers, collect blood to funnel into ventricles

- Ventricles - left ventrivle pumps blood into the aorta, aortic value pumps blood to whole body. Left ventricle is significantly bigger be cos it pumps blood to the whole body, right ventricle pumps blood into the pulmoniac artery and then pulmonary valve

• Valves - one way

- Tricuspid (R)

- Bicuspid (Mitral) (L)

- Defects

Heart-Gross Anatomy:

• Semilunar Valves

- Aortic

- Pulmonary (pulmonic)

• Valvular Function

• Valve regurgitation

• Stenosis - compression getting smaller & smaller!

Coronary Arteries:

• Main Coronary Arteries – Right & Left

Left:

- Circumflex branch

• Feeds left atrium & ventricle

⭐️ Anterior Interventricular branch

- Supplies the anterior walls of both ventricles & the septum

Right:

• Marginal branch – right atrium & ventricle

• Posterior interventricular branch – both ventricles

Heart-Gross Anatomy:

• Blocked Coronary Arteries

• Cardiac Cath:

Heart Muscle:

• Heart as a Pump:

- Initiate & conduct electrical impulses

- Contract synchronously the muscle fibers

- Quickly & efficiently

• Myocardial Tissue: Has 4 key properties:

⭐️ Excitability

⭐️ Inherent rhythemicity

⭐️ Conductivity

⭐️ Contractability

↪ some drugs can effect these!

Vascular Systems:

• Pulmonary:

- Pulmonary artery - deoxygenated blood

- Pulmonary blood pressure

• Systemic:

- Pulmonary vein - oxygenated blood

- Systemic blood pressure

Systemic Vasculature:

• Regulates cardiac output

• Distribution of blood to organs & tissues

• Arterial system

- Highly elastic, low resistance

• Capillary system

- Exchange of nutrients & waste products

• Venous system

- Conduct blood back to heart

- Reservoir system

Neural Control of the Vascular System:

• Sympathetic nervous system

• Vasomotor - located: medulla oblongata

- Vasomotor tone - state of constriction - how constricted?

- Controls vasoconstriction & dilation

• Arterial baroreceptors

• ⬇

• Pressure

- Cardiac center & vasomotor center

• Working to regulate BP

Baroreceptor Reflex:

Pg. 231

• Where are they located?

- Carotid arteries

- Aortic Arch

• What do they do?

- Regulate blood pressure

- Short-term changes

• Other baroreceptors

Cardiac Cycle:

• Ventricle contraction 🟰 systolic pressure

- Compliance & amount of plaque = resistance

• Ventricle relaxation 🟰 diastolic pressure

• Normal blood pressure:

- Systemic 🟰 120/80

- Pulmonary 25/8

↪ pressure in pulmonary system!

Mean Arterial BP (MAP):

• Mean is the average but not calculated as an average

• Systole - pressure in arteries 1/3 of time

• Dystole - pressure in arteries 2/3 of time

⭐️ Formula: MAP = SBP + (2 x DBP) / 3

⬆ ⬆

Systolic BP Diastolic BP

Normal = 80-100

Abnormal - <60 mm Hg blood flow to brain & kidneys compromised > organ failure

Pulmonary Mean Blood Pressure:

• Low pressure system

- Parking garage vs. tube system

⭐️ PAP 15 mm Hg

⭐️ LA 5 mm Hg

⭐️ 10 mm Hg driving pressure vs. 100 mm Hg for systemic

⭐️ Pulses

Blood Volume:

• Stroke Volume (SV): Volume of blood ejected from ventricle w/ each contraction - ONLY AFFECTS LV

• Cardiac Output (CO): Total amount of blood ejected from ventricle each minute

⭐️ FORMULA:

• HR X SV = CO

• DIRECTLY related to Blood Pressure

- HR & SV ⬆ = ⬆ BP

- HR & SV ⬇ = ⬇ BP

Pulmonary Blood Flow:

⭐️Greatest in the bases & Dependent upon:

• Gravity

• Cardiac output

• Pulmonary vascular resistance (PVR) - resistant that the R vent. must push against to get blood flow to the lung

⭐️ Zones:

• Zone I - PA > Pa > Pv

• Zone II - Pa > PA > Pv

• Zone III - Pa > Pv > PA

A = alveolar

a = arterial

Cardiac Output:

• Stroke volume is determined by:

- Ventricular preload

- Ventricular afterload

- Myocardial contractility

Cardiac Output:

Pg. 240

• Ventricular Preload - Diastole

- Degree of stretch prior to contraction ➡ diastole

- Ventricular end-diastolic pressure & volume (more pressure = more volume)

- Frank - Starling Curve

• Greater the stretch = Greater the contraction

Clinical Connection:

Pg. 250

• Clinical Application Section - Case #1

• Automobile Accident Victim/Blood Loss

- Activation of baroreceptor reflux

- Hypovolemia & its relation to preload

- Negative transmural pressure

- Effects of gravity blood flow

Ventricular Afterload:

Pg. 241

• Afterload = Resistance - systole

• Resistance - Force ventricle works against (to pump the blood)

- Resistance to blood flow through the vessels

• Afterload is determined by:

- Volume & viscosity of blood

- Peripheral (Systemic) Vascular resistance

- Cross-sectional area of vascular space

• Blood Pressure reflects:

- Systemic Vascular Resistance (SVR)

Myocardial Contractility:

• Contractility directly affects cardiac output - contractility ⬆ CO2 ⬆

• Assessment of contractility:

- Pulse

- Blood pressure

- Skin temperature

- Hemodynamic measurements

• Positive vs. Negative inotropism

• ↪ Cardiac meds given to increase contractility!

Clinical Connection:

Pg. 242 (5-8)

Pg. 251-252

• Clinical Application Section - Case #2

• Left Ventricular Heart Failure/Pulmonary Edema

- Ventricular afterload

- Ventricular contractility

- Ventricular preload

- Transmural pressure

Vascular Resistance:

• Formula Systemic Vascular Resistance (SVR)MAP/CO

• Vascular Resistancedirectly affects BP

• Increased resistance = ⬆ afterload

• BP monitors afterload

• SVR vs. PVR

⬆ ⬆

systemic pulmonary

⭐️ How do we measure PVR? ➡ MAP

Vascular Resistance:

• Direct affects on vascular resistance:

- Abnormal blood gases

- Pharmacologic stimulation

- Pathologic conditions

Vascular Resistance - Causes:

• Increase blood volume & viscosity

• Decreased vessel size (diameter)

• Pharmacologic stimulation

• Pathologic conditions – diseases

• Abnormal blood gases

• Hypoxia - most common cause of PVR

• SVR - blood pressure

• PVR - Pulmonary Artery Catheter

The Heart:

• Functions as two organs:

- Right side generates lower pressure to drive blood, about 25mmHg

⭐️ Pulmonary vascular system has low resistance

- Left side generates higher pressure, about 120 mmHg

• Systemic vascular system has higher resistance

⭐️ PVR: lower resistance - lungs

⭐️ SVR: higher resistance - whole body

Right vs. Left Sided Heart Failure:

Right - COR PULMONALE

RIGHT VENTRICLE - poor pump

• Chronic lung disease

• Prolonged ⬆ PVR

⭐️ Blood backs up into periphery (liver, legs, JVD - jugular vein)

⭐️ Blood clots

⭐️ Treatment:

• O2

• Blood thinners

Left - Congested Heart Failure

LEFT VENTRICLE - poor pump

• MI over LV is common

• Hypertension (⬆ SVR)

⭐️ Blood backs up into lungs

• Pulmonary edema

⭐️ Hypoxia - difficult to treat!

⭐️ Treatment:

• Need O2 & positive pressure

• Diuretics help ⬇ fluid

• Cardiac drugs