Lab 4: Heart sounds and vessels

Overview

• Review• Heart sounds• Blood supply to the heart• Blood vessels

– Veins• Portal systems• New lab website:

http://isu.indstate.edu/~jowhitak/cmritzi.htm• Practical lab review: Sunday 2-5 pm

Review

• How do volume and pressure in the ventricles change during atrial contraction?

• What region of the heart controls the electrical signal through the heart?

• Which standard limb lead has a negative lead on the right arm and a positive lead on the left arm?

Overview

• Review• Heart sounds• Blood supply to the heart• Blood vessels

– Veins• Portal systems

Heart sounds“lubb-dubb”

• S1: longer and louder• S2: softer and shorter• S3: found in children and juveniles

• S1 & S2 occur in conjunction with the opening and closing of valves

• Actually caused by turbulence of blood

Valvular troubles• Valvular Insufficiency:

valve failure causing backwards flow

• Any defect in the valves can lead to heart failure

• Defective valves can be replaced with artificial valves or with pig valves

Valvular Troubles (cont)

• Mitral valve prolapse: tri- or bicuspid cusps bulge back into the atrium.– Symptoms: chest pain, fatique, shortness of breath– Cause: hereditary

• Valvular Stenosis: cusps of the valve are stiff and opening is constricted by scar tissue– Results from autoimmune disease– Causes enlarged heart– Blood moving backwards through the valves causes a heart

murmur

Break for Dynamic Human

Blood supply to the heart muscles

• The endocardium prevents blood from seeping through the heart

• How is blood supplied to the myocardium and the pericardium?– Coronary arteries originating from the aortic

arch

Arteries in the heartAorta

Right Coronary Left Coronary

Marginal artery Circumflex Artery Posterior IV Artery Anterior IV Artery

Anastomoses

Anastomoses

• Point where two arteries join to reach a common destination

• If one artery becomes blocked, the other can take blood to the appropriate destination

Arteries of the heart

Veins in the heart

Greater Cardiac Vein Small Cardiac Vein

Middle Cardiac Vein

Coronary Sinus

Right Atrium

Coronary Veins

Artherosclerosis

• Contributes to over 710,000 heart attack and stroke, and

peripheral vascular disease deaths each year. • Fatty blockage in

coronary artery

Artherosclerosis

• Cause: Abundance of low-density lipids and defective receptors for LDL in the coronary arteries.– LDL: cholesterol, free fatty acids and

phospholipids– Arterial cells with defective receptors will take

in too much cholesterol– Results in obstruction of the arterial lumen

Cardiac Ischemia and Infarction

• Ischemia: Loss of blood flow• Infarction: Death of myocardial cells; heart attack

• Cause: Artheriosclerosis blocks a cardiac artery. The downstream region does not receive enough oxygen causing cell death. The death of these cells weakens the heart wall disrupting electrical pathways leading to fibrillation.

Break for Dynamic Human

Overview

• Review• Heart sounds• Blood supply to the heart• Blood vessels

– Veins• Portal systems

Blood Vessels

Arteries

Capillaries

Veins

Structure of Blood Vessels

• Tunica externa: loose connective tissue

• Tunica media: smooth muscle, elastin, collagen

• Tunica interna: endothelium

Types of Arteries

• Conducting (elastic)– Passively accommodate blood flow

• Distributing (muscular)– High smooth muscle content– Deliver blood to specific organs

• Arterioles– Control blood flow– Link to capillaries

Capillaries

• Pre-capillary sphincters– Open and close

capillary beds– ¾ of all capillaries are

ususally closed

• Structure: endothelium only

Types of Capillaries• Continuous:

uninterrupted tube– Only allow small solutes

such as glucose to enter– Blood-brain barrier

• Fenestrated: riddled with pores– Allow rapid passage of

small molecules– Hold proteins in the vessels– Important in organs that

engage in rapid filtration

Veins

• Venules: Collect blood from capillaries– Porous

• Veins: – Lower pressure than the arteries– Thinner walls (little tunica media or externa)

but larger lumens– Walls expand easy and accomadate more blood

than arteries

How does blood travel in veins?

1. Messaging action of skeletal muscle

2. Pressure gradient in the body:– Positive pressure in the abdominal cavity and

negative in the thoracic cavity draws blood up

Venous Valves

3.Venous valves prevent backflow

• Failure of valves results in varicose veins

Special Circulations: Portal Systems

• Portal systems: Blood flows between two consecutive capillary beds before returning to the heart

Artery

Capillary 1

Capillary 2

Vein

Hepatic Portal System

• Connects capillaries of the intestines to capillaries of the liver

• Delivers newly absorbed nutrients to the liver

Hypothalamo-hypophyseal portal system

• Connects hypothalamus to pituitary gland

• Responsible for transporting hormones

Dynamic Human

Overview

• Review• Heart sounds• Blood supply to the heart• Blood vessels

– Valves• Portal systems• Cat heart and human heart

Cat Dissection

• Finish identifying arteries and veins

• Remove cat heart and dissect in half– Valves and chambers– Chordae Tendinai– Coronary Arteries