CH 22 - Heart (NOT COMPLETE)

Arteries

carry blood away from heart

Capillaries

Network through tissues/organs.

Veins

carry blood to heart.

Right Atrium

Collect blood from systemic circuit

Right ventricle

Pump blood to pulmonary circuit

Left atrium

Collect blood from pulmonary circuit

Left ventricle

Pump blood to systemic circuit

Heart anatomy (upside down pyramid)

Great vessels at base, pointed tip is apex, in pericardial sac in mediastinum.

Superficial Anatomy of the heart

Atria: thin walled, expandable outer portion called the auricle. Coronary sulcus (groove) between the 2 atria and ventricles. Anterior and posterior interventricular sulci. KNOW ALL EXTERNAL HEART ANATOMY FROM SLIDES

Heart wall: Epicardium

superficial, Visceral pericardium

Heart wall: Myocardium

2nd layer. Thickest, cardiac muscle

Heart wall: Endocardium

deepest, simple squamous epithelium.

Internal Anatomy: Interatrial Septum

Foramen ovale–before birth, seals off at birth forming fossa ovalis. In the right atrium

Internal Anatomy: Atrioventricular (AV) Valves

Bicuspid–Between left atrium and left ventricle

Tricuspid–Between right atrium and right ventricle.

KNOW THE LOCATIONS

Internal Anatomy: Superior Vena Cava

Blood from head, neck, upper, limbs, and chest

Internal Anatomy: Inferior Vena Cava

Blood from trunk, viscera, and lower limbs

Internal Anatomy: Coronary Sinus

From cardiac veins

Tetanus in heart

Impossible since the heart muscles have a long refractory period unlike skeletal muscle.

muscle in Right Atrium

Pectinate muscles–Parallel muscular ridges

Right atrioventricular (AV) valve

tricuspid valve, chordae tendineae. Prevent valve from flopping backwards

muscle in Right Ventrical

Papillary muscles: trabeculae carneae, attach to chordae tendineae, control closing

Pulmonary Circuit: Conus arteriosus (Location)

Superior right ventricle

Pulmonary Circuit: Pulmonary semilunar valve

3 semilunar cusps

Pulmonary Circuit: Pulmonary trunk

right and left pulmonary arteries

Pulmonary Circuit: Left Atrium

Left and right pulmonary veins

Pulmonary Circuit: Left ventricle

Larger thicker, same volume as right. Aortic semilunar valve, ascending aorta, aortic arch: head, chest, upper limbs. Descending aorta: trunk and lower limbs.

Pulmonary Circuit: Left (AV) valve

bicuspid valve or mitral valve

Cardiac Skeleton

Fibrous collagen skeleton that supports and insulates the heart. The layer of nonconductive tissue isolates the atria from the ventricles. Exception of one small node that carries the signal across the skeleton. Atria contract before the ventricles, but this only takes one signal since it slows down between the atria and ventricles. “Lub-Dub”

Coronary Circulation: Arteries

Right and left coronary arteries travel within the coronary sulcus and supply the heart wall with oxygen and nutrients. Blood flows into heart wall when the heart relaxes and pressure falls.

Coronary Circulation: Veins

Return of blood from the heart wall occurs through 3 major veins: Great, Middle, and Small cardiac veins.

Heart Disease – Coronary Artery Disease (CAD)

Coronary ischemia: Area of partial or complete blockage of the coronary circulation.

Atherosclerosis: plaque on the wall of a coronary vessel.

Coronary thrombosis: Narrowed/blocked vessel

Myocardial Infarction (MI)

Heart attack. Cardiac cells die from lack of oxygen. Infarct: nonfunctional area of necrotic tissue. Block begins at beginning of coronary artery. 65% of MI deaths under age 50 within 1hr

Drugs that help with heart attacks

Nitroglycerine is a powerful vasodilator.

Balloon angioplasty

Catheter tip stuck into artery, balloon opens up to crush plaque. Stent hold vessel open.

Coronary artery bypass graft (CABG)

Vessel added to create detour around blockage.

Autorythmicity

The heart initiates its own heartbeat independent of the central nervous system. The CNS only speeds or slows down the rate.

Conducting System

Specialized cells that start and propagate electrical impulses to contractile cells.

Prepotential

This is how the heart beats without nervous signaling. Membrane gradually depolarizes and contains leak channels(ions leaked during resting state until threshold is met and another action potential fires).

1. P wave

Atrial depolarization. Positive blip

2. QRS complex

ventricular depolarization (Positive blip) and atrial repolarization (Negative blip)

3. T wave

Ventricular repolarization (Negative blip). This repolarization is negative since ventricles are the first to repolarize. So the wave shows an inverted negative blip which looks positive.

Bradycardia

abnormally slow heart rate

Tachycardia

abnormally Fast heart rate

Systole=

Contraction

Diastole=

Relaxation

Steps in the Cardiac Cycle

Atrial contraction and ventricular filling→Isovolumetric contraction→Ventricular ejection→Isovolumetric relaxation→Atrial relaxation and ventricular filling