All Heart or No Brains?

Cardiovascular & Respiratory Systems

Question: How much does a Normal Heart Weigh?

A. 5 ouncesB. 11 ouncesC. About 1 poundD. 2.5 pounds

B. 11 Ounces on average. (The average brain weighs 3 pounds or 48 ounces)

StatisticsBeats per Minute = 60-80Beats per Day = 100,000Beats per Year = 35 MillionBeats per Lifetime = 2.5 Billion

*Blood Pumped per minute (Rest) = 5 Liters/ 5 Quarts

Blood Pumped to over 75 Trillion Cells in BodyThrough over 60,000 miles of vessels

*Cardiovascular System

Cardio – pertaining to HeartVascular- = a little vessel, consisting of cells joined into tubes for transporting/circulating

CV system – Body system transports nutrients, gases, hormones, cellular waste products.

*Major Cardiovascular Functions

w Delivery:. oxygen and nutrients

w Removal: carbon dioxide and waste products

w Transportation: hormones

w Maintenance: body temperature, pH

w Prevention: infection (Helps Immune System function)

Origin of Heart Shape

7th century B.C. city-state of Cyrene. Cyrene traded the rare, now extinct, plant silphium. It was known as a means for birth control. The seedpod of the silphium looks exactly like a valentine's heart. Moreover, its use in sex is an obvious connection to love

Heart is Center of All Emotions. Heavy Heart

The Circulatory System

Heart Pumps blood

Arteries and arterioles Carry blood away from the heart

Capillaries Exchange of nutrients with tissues

Veins and venules Carry blood toward the heart

The Basics

Thump-thump?

Blood Vessels Artery - a high-pressure vessel, possess a thick layer of

smooth muscle to help off set the high blood pressures it must endure, can constrict or dilate (Major Arteries)

Arteriole - a resistance vessel, possess a circular smooth

muscle layer, is the primary site of blood flow regulation

Capillary – site of nutrient transfer (Diffusion)

Venule – a pre-vein, small amount of muscle

Vein – a capacitance vessel, very elastic, capable of “holding” blood; posses valves to prevent backflow

BLOOD DISTRIBUTION AT REST

The Skeletal Muscle Pump

Rhythmic skeletal muscle contractions force blood in the extremities toward the heart

One-way valves in veins prevent backflow of blood

Pulmonary & Systemic Circuits

VR-RA-RV-Lungs-LA-LV-Aorta-Body

Coronary Arteries-Heart

Respiratory System

Circulatory System

*AortaThe Main artery & Largest (elastic). When the left ventricle contracts to force blood into the aorta, the aorta expands. This stretching gives the potential energy that will help maintain blood pressure during diastole as during this time the aorta contracts passively.

Structure of the Heart

Left Ventricle

The left ventricle receives oxygenated blood from the left atrium via the bicuspid valve. The blood is then transported throughout the body.

The thick walls of the left ventricle pumps blood to the aorta, the systemic arteries, the capillaries, the veins, and back to the right atrium.

The left ventricle is also the main function of stroke volume and cardiac output.

Cardiac Output Graph (11)

Muscles receive most of the cardiac output during exercise because the muscles are the ones doing

most of the work!

Heart Wall Anatomy

Epicardium – a connective tissue covering of the heart which contains blood vessels, lymph vessels, and nerve endings; provides a lubrication buffer for the heart

Myocardium – the cardiac muscle layer; the myocardium will be discussed in greater detail in the next slide

Endocardium – the inner layer of endothelial cells and more collagen (connective) tissues

Myocardium—The Cardiac Muscle

w Thickness varies directly with stress placed on chamber walls.

w Left ventricle is the most powerful of chambers and thus, the largest.

w With vigorous exercise, the left ventricle size increases.The heart has autoconduction, i.e., it beats on its own without nerve or hormonal control. Due to intercalated disks—impulses travel quickly in cardiac muscle and allow it to act as one large muscle fiber; all fibers contract together.

Fig 9.3

Myocardium

Myocardium is striated muscle tissue, so it has some similar aspects to skeletal muscle

However, it also has several qualities which are much different

Myocardium cont. Differences from skeletal muscle:

*Only one fiber type, so there are no fiber-type differences within the myocardium

Cardiac muscle fibers are relatively short. Most are only a few hundred sarcomeres in length

*Cardiac muscle is not voluntary muscle

Cardiac muscle fibers are connected by intercalated disc; creates a functional syncytium

The Myocardium

Electrocardiogram

*Records the electrical activity of the heart

P-wave Atrial depolarization

QRS complex Ventricular depolarization

T-wave Ventricular repolarization

CardiacCycle

&ECG

Review

Video

Breathing Mechanics http://youtu.be/hp-gCvW8PRY Normal Inspiration: Diaphragm contracts (shortens) creating a vacuum in the chest cavity.

Normal Expiration: Diaphragm relaxes and the chest cavity collapses forcing air out.

Exercising Inspiration: Diaphragm, intercostal, and abdominal muscles contract to lift the rib cage and create a greater vacuum in the chest cavity.

Exercising Expiration: All muscle relax and the chest cavity collapses forcing air out.