BIOL Module 4 Chapter 15

What are some functions of the heart?

generates blood pressure, routing blood, ensuring one-way blood flow, regulates blood supply by changing heart rate

Characteristics of the heart

Heart - hollow, cone-shaped, muscular pump

Blood vessels - transports blood through the body

Arteries - transports blood away from the heart

Veins - transports blood back to the heart

What are the two closed circuits (pathways) of the heart?

Pulmonary circuit - right side; carries oxygen-poor blood from the heart to the lungs, drops off carbon dioxide and picks up oxygen, then flows to the left side of the heart

Systemic circuit - left side; transports oxygen-rich blood to the body cells, then flows back to the right side of the heart

Where is the base of the heart? Where is the apex of the heart?

Base - lies beneath the 2nd rib

Apex (point) - lies at the 5th intercostal space

What are the coverings/layers of the heart?

Fibrous pericardium - tough outer layer

Parietal pericardium - deep to fibrous pericardium; outer layer of serous membrane

Visceral pericardium (epicardium) - inner layer of serous membrane; attached to surface of heart

Pericardial cavity - space between visceral and parietal layers of serous pericardium

What are the walls of the heart?

Epicardium (visceral pericardium) - outer layer, thin, reduces friction

Myocardium - middle layer, thickest layer, cardiac muscle tissue

Endocardium - inner layer, thin, forms inner layer of all heart chambers

What are the chambers of the heart?

Right atrium - receives blood from the inferior and superior vena cava, pumps blood to the right ventricle

Right ventricle - receives from right atrium, pumps blood to lungs

Left atrium - receives from right ventricle, pumps blood to left ventricle

Left ventricle - receives from left atrium, pumps blood to systemic circuit

What are the heart valves?

Tricuspid valve (right atrioventricular valve) - separates right atrium from right ventricle

Pulmonary semilunar valve - separates right ventricle from pulmonary trunk

Mitral (left atrioventricular valve) - separates left atrium from left ventricle

Aortic semilunar valve - separates left ventricle from aorta

Electrocardiogram

P wave - atrial depolarization; occurs just prior to atrial contraction

QRS complex - ventricular depolarization; occurs just prior to ventricular contraction

T wave - ventricular repolarization; occurs just prior to ventricular relaxation

Heart sounds

“Lubb” (S1) - occurs during ventricular systole; associated with closing of AV valves

“Dupp” (S2) - occurs during ventricular diastole; associated with closing of pulmonary and aortic semilunar valves

What is a heart murmer?

abnormal heart sound derived from the incomplete closing of the cusps of a valve

What part of the brain is responsible for vital functions?

Medulla oblongata, Pons, Midbrain

Parasympathetic impuse

“rest and digest” - slower heart, more digestion

Sympathetic impulse

“fight or flight” - faster heart, less digestion

Blood Vessels

Arteries - carries blood away from the ventricles of the heart

Arterioles - receives blood from the arteries, caries it to the capillaries

Capillaries - sites of exchange of substances btwn the blood and the body cells

Venules - receives blood from capillaries, conducts it to veins

Veins - receives blood from venules, carries it back to the atria of the heart

Characteristics of arteries

narrower lumen diameter than veins

thicker walls than veins

thickest tunic is the tunica media

more elastic and collagen fibers than in a vein

no valves

higher BP than in veins

transports blood away from heart

systemic arteries transport blood high in O2

pulmonary arteries transport blood low in O2

Characteristics of veins

wider lumen diameter than arteries

thinner walls than arteries

thickest tunic is the tunica externa

less elastic and collagen fibers than in an artery

valves are present in most veins

lower BP than in arteries

transports blood to the heart

systemic veins transport blood low in O2

pulmonary veins transport blood high in O2

Exchanges in capillaries: Diffusion

most important method of transfer

lipid-soluble substances diffuse through cell membrane

water-soluble substances diffuse through membrane channels and slits

Exchanges in capillaries: Osmosis