Cardiac Lecture PPT pt. 1 - Mrs. Allison

Parts of systemic circulation

arteries, arterioles, capillaries, venules, veins

Steps of cardiac cycle

1) atrial systole

2) isovol. ventricular contraction

3) ejection

4) isovol. ventricular relaxation

5) passive ventricular filling

Stroke Volume (SV) definiton

volume of blood ejected from the heart with each contraction

Equation for Cardiac Output (CO)

SV x HR

3 Factors that affect Stroke Volume (SV)

1) Preload

2) Afterload

3) Contractility

Preload

(= think “volume”)

volume of blood in the ventricle at the END of diastole

Preload, (think volume), determines what???

degree of stretch of the LV

When preload is HIGH, how is SV and CO affected?

both SV and CO increase

When preload is LOW, how is SV and CO affected?

both SV and CO decrease

Afterload =resistance

the pressure (vascular resistance) the heart must work against to eject blood during systole

Aortic pressure/resistance (afterload) affects emptying of the ____ ________.

Left Ventricle

When afterload is HIGH, how are SV and CO affected?

both SV and CO decrease

Cardiac/peripheral vascular problems likely will result from either…

problems with the pipe = veins, arteries, capillaries

problems with the pump = heart

Inner lining of artery

endothelium → contains endothelial cells

Muscular tube of artery

involuntary smooth muscle, controlled by ANS

Most important structure of the artery

endothelial inner lining

*vulnerable to injury

Major arteries to know

-aorta

-coronary arteries

Parts of Endothelium *critical for arterial function

Inner to Outer

1) Endothelium

2) Basal lamina

3) Elastic lamina

4) Smooth muscle

5) Adventita *connective tissue

What do endothelial cells release?

1) Nitric oxide

2) Endothelin

3) VEGF

4) Thromboxane A2

5) Prostacyclin

6) von Willebrand factor

Nitric oxide

stimulates vessel vasodilation

Endothelin

stimulates vessel vasoconstriction

VEGF (Vascular Endothelial Growth Factor)

stimulates growth of new blood vessels

Thromboxane A2

activates clotting

Prostacyclin

inhibits clotting

von Willebrand factor

activates clotting

Powerhouse of the heart

left ventricle

Things that can cause Endothelial Cell injury?

-Hypertension

-Free radicals (ex: smoking)

-High glucose

-Hyperlipidema

How can hypertension damage the endothelium?

high shearing force damages endothelium

How can free radicals damage the endothelium?

substances attack the endothelium and disrupt its integrity

(ex: smoking)

How can high glucose damage the endothelium?

with diabetes, glucose attaches to endothelial cells and disrupts their integrity

How can hyperlipidemia damage the endothelium?

LDL—combined with WBCs in the endothelial artery wall to initiate atherosclerosis

Consequences of endothelial cell injury

-diminished nitric oxide → less vasodilation ability

-endothelin secretion → vasoconstriction

-thrombogenic substance secretion → more arterial blood clotting

-injury inflammation → WBC bring lipids → foam cells → fatty streak → atherosclerotic plaque

Atherosclerosis

chronic disease of the artery characterized by plaque buildup

*abnormal hardening + thickening of vessel wall

primary cause of CAD

Steps of Atherosclerosis

1) damaged endothelium

2) inflammation

3) foam cells

4) fatty streak

5) fibrous plaque *contains collagen cap

6) complicated lesion

3 Stages of Acute Inflammatory Reaction

1) Vasodilation → histamine, bradykinin, prostaglandin

2) Vascular permeability

3) Cellular migration → wbc, platelets

4 Markers of Inflammation

1) C reactive protein (CRP)

2) Erythrocyte sedimentation rate (ESR)

3) Leukocytosis (high WBC)

4) Lactic Acid

CRP - c reactive protein

*a marker of inflammation

normal: < 3 mg/dl

elevated lvls of hs-CRP (high sensitivity) are associated w/ CVD

ESR erythrocyte sedimentation rate

*a marker of inflammation

normal: 0-29mm/hr

Leukocytosis = high WBC count

*a marker of inflammation

normal: 5,000-10,000 cells/cm

Lactic acid → linked to sepsis

*a marker of inflammation

normal: <2 mmol

Sepsis definition

A systemic inflammatory response syndrome (SIRS) due to infection

Lipids are mainly composed of…

cholesterol

Cholesterol

main component of lipids

-fatty, steroidal substance

-ingested from diet

-synthesized by LIVER

2 types of lipoproteins

LDL → low density lipoproteins

HDL → high density lipoproteins

which lipoprotein is good?

HDL, it is excreted by the body

which lipoprotein is bad?

LDL, it builds up on artery walls

Coronary Artery Disease (CAD)

narrowed/blocked coronary arteries due to plaque buildup

*plaque = cholesterol / fatty buildup

atherosclerosis is the #1 cause of this disease

Repeated ischemia

occurs when the heart does not receive enough blood flow over time, leading to chest pain or discomfort

leads to a weak heart → even MI (heart attack!!!)

BP regulation

uses arterial pressure

How does arterial pressure regulate BP?

use of…

CO (preload)

Total Peripheral Resistance (afterload)

Baroreceptors

Hormones

Hormones that regulate BP

Epinephrine, norepinephrine, (← both in ANS)

ADH, RAAS

Baroreceptors

specialized stretch receptors that detect major changes in BP (through the amt. of stretching) and sends signals to brain to keep BP stable

Anti-Diuretic Hormone (ADH)

acts on kidneys by REABSORBING more water in plasma

= increases plasma volume

Renin Angiotension Aldosterone System (RAAS)

A hormone system that regulates blood pressure and fluid balance by controlling BV constriction and Na+ retention

Renin

hormone released from kidney after a drop in BP, BV, and/or Na+

acts on angiotensinogen to form Angiotensin I

ACE (angiotensin-converting enzyme)

an enzyme released from the lungs

acts on Angiotensin I to form Angiotensin II

Angiotensin II

acts on the adrenal gland to stimulate release of Aldosterone

-also stimulates VASOCONSTRICTION of BV

Aldosterone

acts on the kidneys to stimulate reabsorption of NaCl + H2O

this then increases BV + BP

Murmur v.s. Bruit

murmur = an abnormal whooshing sound org. inside the heart

bruit = an abnormal whooshing sound org. from blood flow in an artery

What side of the stethoscope is used for listening to the carotid artery

bell side (smaller side)

Points for listening to heart sounds

listening to heart sounds include the aortic area, pulmonic area, erb’s point, tricuspid area, mitral area