Animal Circulation

The Cardiovascular System• Coordinated activities such

as growth and homeostasis depend on: – transfer of ions, waste

products, signaling molecules, transport proteins, and other substances within the body

• The circulatory system is a internal transport system consisting of:– blood vessels, a muscular

heart, and fluids

Cellular Respiration• One very important process

that takes place in all of your cells is cellular respiration.

• How all of your cells get energy from food

• How do all of our cells get O2 and glucose to them?

• What about getting rid of CO2?

Respiratory and Circulatory systems!

Blood Contains Many Different Cell Types• Blood plasma is the fluid

portion of blood and is 92 percent water; it contains dissolved gases, ions, and molecules

• Red blood cells contain oxygen-binding proteins called hemoglobin for transporting oxygen throughout the body

• White blood cells are involved with fighting foreign substances

Blood Contains Many Different Cell Types

• Platelets are fragments of larger cells that clump together to help staunch the loss of blood if a vessel is damaged

The Human Heart Pumps Bloodto the Body through Two Circuits

• The pulmonary circuit flows between the heart and the lungs

• deO2 to lungs to pick up oxygen and unload CO2

• The systemic circuit flows between the heart and the body

• O2 rich blood to all body cells and removes wastes

The Human Heart

• The human heart is divided into four chambers that create two physically independent pumping units

The Human Heart• The chambers on

the right and left sides of the heart are separated by a thick wall of tissue called the septum

• The upper chambers: atria

• The lower, larger chambers are called the ventricles

The Human Heart• The chambers on the

left side of the heart receive oxygenated blood returning from the lungs and pump it through the systemic circuit

• The two chambers on the right side of the heart receive blood returning from the systemic circuit that is low in oxygen and laden with CO2 and pump it through the pulmonary circuit

• The atria contract simultaneously and move blood to the ventricles

• The ventricles have large, muscular walls, which are required for moving blood out of the heart

The Human Heart

The Human Heart

• The atria and ventricles are separated by valves that allow blood to flow in only one direction

Measuring the Heart

• The heart rate is the number of times the heart beat per minute and can be measured as the pulse rate

• Blood pressure measures the pressure in the arteries leading to the body from the left ventricle

• The beating of the heart is part of the cardiac cycle, which is made up of a relaxation phase and a contraction phase

The Cardiac Cycle: Heartbeat

• The cardiac cycle is made up of a relaxation phase and a contraction phase

• Diastole: relaxation phase of the cardiac cycle

The Cardiac Cycle: Heartbeat

• Systole is the pumping phase, during which blood is pumped– first from the

atria to the ventricles

– then from the ventricles to the lungs

– Then to the rest of the body

The Cardiac Cycle: Heartbeat

The Cardiac Cycle: Heartbeat

• The signal to contract is delivered to the heart muscle by a group of specialized cells in a region of the heart called the sinoatrial (SA) node

• The signals from the SA node are relayed to the atrioventricular (AV) node

• If the SA node is not working correctly an artificial pacemaker is sometimes implanted

The Cardiac Cycle: Heartbeat

• Written as a ratio of systolic to diastolic pressure– for example:

120/80 mmHg• Systolic pressure

represents the higher value in a blood pressure reading and diastolic pressure is the lower value

Blood Pressure

Blood Vessels• Arteries branch many

times to form a network of arterioles that carry blood from the heart for distribution to the body and control the flow of blood to the capillaries

• Arteries have highly elastic walls that enable them to stretch when a heart contraction increases the blood pressure

• All blood flowing away from the heart is in arteries

Blood Vessels

• Capillaries allow the exchange of materials between the blood and the surrounding interstitial fluid and cells

Capillary bed of the thyroid gland

Blood Vessels

• Capillaries have extremely thin, porous walls across which materials diffuse easily

• The large surface area of capillaries ensures efficient exchange of gases, nutrients, and other materials with the surrounding interstitial fluid, and in turn with respiring cells

Blood Vessels• Veins bring

deoxygenated blood back to the heart via a network of increasingly larger vessels

• All blood flowing towards the heart is in venules or veins

• Veins have specialized one-way valves to keep blood flowing toward the heart against gravity

• Yes, exercising keeps your blood flowing!!

Blood Vessels

The Cardiovascular System and Homeostasis• The heart can be

influenced by the nervous system and signaling molecules

• Norepinephrine is a neurotransmitter that causes the cells of the SA node to signal the heart to beat faster and more forcefully under stressful situations

• Changes in body temperature and exercise can also affect the heart rate of an individual

The Cardiovascular System and Homeostasis