EXAM 3 Coronary Circulation

_______ layer can obtain substances from blood in heart chambers

Endocardial layer ca obtain substances from blood in heart chambers

Diameter of endocardial layer

0.1 nm

Small arteries penetrate into ______

Small artieries penetrate into cardiac muscle

What are the two coronary arteries and where are they found?

There are 2 coronary arteries

1. Left Coronary Artery

2. Right Coronary Artery

They lie on the surface of the heart

Coronary venous sinuses takes blood from?

Left ventricle cells

What percent of venous return are the coronary venous sinuses responsible for?

75%

Where do the anterior cardiac veins take blood from

right ventricular cells

What percent of venous return are the coronary anterior cardiac veins responsible for

20%

What is 3-5% of venous blood return done by

Thebesian circulation

Subendocardial arteries primarily flow during

diastole

Blood Supply of the heart wall

Arteries→ ______→_______

Blood Supply of the heart wall

Arteries→ perpendicular small branches→network of arteries and capillaries

One capillary for one_____

Heart wall has a rich supply of _____

Myocyte

Heart wall has a rich supply of capillaries

What is normal coronary blood flow during rest?

250 ml/min

What percent of coronary blood flow accounts for cardiac output (CO)

4-5%

Mass of adult human heart

250-300 g

This means coronary blood flow is ____ ml/min/g

This means coronary blood flow is 1 ml/min/g

Blood flow equation

ml per min divided by grams

80% of coronary blood flow occurs during

diastole

Heart is characterized by intensive ______

Heart is characterized by extensive metabolism

Heart needs uninterrupted supply of _____ and _____

heart needs uninterrupted supply of glucose and oxygen

Myocardial O₂ consumption at rest is

8-10 ml/min /100 g

Coronary venous O₂ content at rest ____

5ml/ 100 ml

O₂ content in mixed venous blood is

15ml/ 100 ml

Heart consumes more O₂ than the rest of the body

How much O₂ is consumed in the heart vs the body

Heart consumes: 16 ml O₂ /100 g (21 Arterial - 5 venous )

Body Consumes: 5ml O₂ /100 g (21 arterial - 16 venous)

Atherosclerosis causes a decrease in _____

Coronary Blood Flow

Does Coronary Blood Flow (CBF) increase or decrease during myocardial ischemia

Coronary Blood Flow (CBF) DECREASES during myocardial ischemia

_____ of the coronary _____ and Superimposed ____ are responsible for ischemia

Atherosclerosis of the coronary arteries and superimposed thrombosis are responsible for ischemia

What is ischemia?

Ischemia may produce _____ or _______

Ischemia is a decrease of blood flow to a part of the body

ischemia may produce arrhythmias or myocardial infraction

TRUE or FALSE

ischemia is only chronic disease

FALSE

Ischemia can be BOTH Chronic or Acute

During Myocardial Infractions

Increase in:

Decrease in:

During Myocardial Infractions

Increase in:

• Intracellular Ca²⁺

• H⁺

• Lactate

Decrease in:

• ATP

• O₂ Delivery

• Na⁺/K⁺ ATPase

During myocardial infraction

(increased or reduced) Coronary Circulation

(increased or reduced) Contractility

(increased or reduced)Stroke Volume

(increased or reduced) Cardiac Output

ALL REDUCED

What are the three major systems that are in control during Coronary Blood Flow

• humeral

• nervous

• local metabolism

LOCAL METABOLISM

Blood flow through the coronary system is regulated by ________

Local metabolism of the coronary blood flow is ____ term

Blood flow through the coronary system is regulated by local arterial vasodilation

Local metabolism of the coronary blood flow is short term

Increase in Cardiac output causes an increase in______ according to the ______

Increase in cardiac output causes an increase in blood flow according to the adenosine theory

LOCAL METABOLISM

What substances might affect coronary flow

• ADENOSINE

• carbon dioxide

• lactic acid

• potassium

• histamine

• hydrogen

• nitric oxide

Humeral System affecting Coornary Blood Flow

Humoral blood flow is controlled by ____ and ____ agents

Humeral blood flow is controlled by vasoconstrictor and vasodilator agents

Vasocontrictor agents:

• vasopressin

• endothelin

• angiotensin

• norepinephrine

• epinephrine

Vasodilator Agents:

• Epinephrine

• bradykinin

• serotonin

• histamine

• prostaglandins PGI

• nitric oxide

Norepinephrine receptors=

alpha receptors = norepinephrine

epinephrine receptors

alpha OR Beta= Epimephrine

______ nervous system can affect coronary circulation both ____ and ______

ANS (autonomic nervous system) can affect coronary circulation both directly and indirectly

ANS affect coronary circulation directly through the ____ and _____ effects upon coronary blood vessels

ANS affects coronary circulation directly through the sympathetic and vagal (vagus nerve) effects upon coronary blood vessels

ANS can indirectly affect coronary blood flow through autonomic effects upon ______

ANS can indirectly affect coronary blood flow through autonomic effects upon myocardial contractility

What effects ?

• Inotropic effect

• chronotropic effect

• dromotropic effect

• vasodilatory effect