Circulatory System

Transports materials throughout the body  Diffusion alone is a slow process so your body uses the circulatory system to speed the movement of essential nutrients and gases  Also transports hormones and waste to and from cells  3 main components Heart – multi-chambered muscular organ Blood – connective tissue made of cells and fluid Blood vessels - muscle tissue and connective tissue  Enable it to expand and contract as blood flows through it  Carries material from heart to the rest of the body and back In the margin write two questions about the structure and function of the C.S.

More activity requires greater circulation….WHY?  3 Types of Blood Vessels Arteries  Moves blood away from heart under pressure (ensure uni-directional flow)  Thick wall of epithelial tissue wrapped in layers of smooth muscle and connective tissue  Muscle tissue enables the artery to constrict and to dilate Veins  Moves blood to the heart under less pressure but has valves (ensure uni- directional flow)  Thinner wall of epithelial tissue relative to arteries Capillaries  Walls of capillaries consist of a very thin layer of epithelial tissue encased in a moist membrane  Enables the diffusion of nutrients and oxygen out of the blood and the diffusion of waste products into the blood

How does the transport of materials occur?  Capillaries and cells do not come in direct contact Substances enter interstitial fluid then enter cells Small molecules (oxygen, carbon dioxide, waste) diffuse directly from blood cell to somatic cell or vice versa Larger molecules move via endocytosis and exocytosis

Chemical Exchange  Blood pressure forces fluid through capillary walls. Artery end forces fluid out (higher blood pressure). Vein end allows fluid into capillary (lower blood pressure).

Lymphatic System  Your blood loses 4 liters of fluid into the interstitial fluid daily.  Lymphatic systems returns this fluid to the circulatory system near the heart. Made up of capillaries and larger vessels that reach every part of the body. Fluid is called lymph. In the margin describe how materials such as oxygen move from the blood into a tissue cell. Then explain to your neighbor the role of the lymphatic system.

The heart pumps blood throughout the circulatory system  Two pathways of blood flow The pulmonary circuit carries oxygen-depleted blood from the heart to the lungs and oxygen-rich blood back to the heartpulmonary circuit The systemic circuit carries oxygen-rich blood from the heart to the rest of the body and oxygen-depleted blood back to the heartsystemic circuit Blood flows through both circuits at the same time Ensures that oxygen-rich blood is constantly delivered to cells

Pathway of Blood  Most arteries in the body carry oxygen-rich blood, while most veins carry oxygen-depleted blood  Pulmonary circuit do the exact opposite Pulmonary arteries carry oxygen- depleted blood to the lungs Pulmonary veins carry oxygen-rich blood from the lungs to the heart

Tracing the Path  1.Blood travels from the right side of the heart through pulmonary arteries to the lungs.  2.Blood picks up oxygen in the lungs.  3.Pulmonary veins return the oxygen-rich blood to the left side of the heart.  *Note: Pulmonary circuit

Tracing the Path  4.Oxygen-rich blood leaves the left side of the heart through aorta.  5.Flows through branching arteries to the capillaries. Oxygen diffuses out and Carbon dioxide diffuses in.  6.Oxygen-depleted blood returns to the right side of the heart through veins. *Note:Systemic Circuit

Anatomy of the Heart  Atria (2) – upper chambers of the heart receiving blood coming to the heart Always flow into ventricles  Ventricles (2) – lower chambers of the heart pumping blood Thick walls due to greater blood pressure  Pericardium – fluid filled sac around heart to cushion the organ  Valves in the heart prevent backflow of blood into other chambers 4 chambers is more efficient

Draw a heart, label the 4 chambers, and trace the blood flow.

Regulating Heartbeat  Pacemaker – sets the rate for your heart to contract In the walls of the right atrium Sends electrical impulse for atrium to contract Sends signal to AV node which triggers the ventricles to contract

Draw the electrocardiogram and label the stages of the heartbeat.

Controlling the Pacemaker  Pacemaker is controlled by: Nervous system and the endocrine system  Two sets of opposing nerves.  Speed it up or slow it down. Hormones secreted into the blood also control the pacemaker  Epinephrine, aka adrenaline

Blood Pressure  Diastole – The period of time when the heart fills with blood between muscle contractions.  Systole - atria contract, and blood is forced into the ventricles, which are relaxed Then the ventricles contract, pumping blood into arteries, while the atria are relaxed This cycle repeats about every second when you are resting.  Blood pressure is represented by two numbers separated by a slash, such as 120/70 It is measured in millimeters of mercury (mm Hg), a standard unit of liquid pressure The first number is referred to as systolic pressure, the highest recorded pressure in an artery when the ventricles contractsystolic pressure Diastolic pressure, the second number, is the lowest recorded pressure in an artery during the relaxation phase of the heartbeat Diastolic pressure As a person ages, blood pressure may increase  Smoking or a fatty diet can contribute to this increase by causing arteries to become less elastic

Summary  At the bottom of page 1 write a short summary about the structure and function of the circulatory system.

Blood consists of cells suspended in plasma  Function of Blood Deliver oxygen, water, and nutrients to body Remove carbon dioxide and waste Disperse hormones throughout the body Fight infections and heal wounds (loose connective tissue form matrix)  scabs

Anatomy of Blood  Plasma 55% of total volume  90% water  10% dissolved salts and proteins  Red Blood Cells aka erythrocytes Formed in bone marrow Carry oxygen with help from hemoglobin (protein) Mature RBC’s lose nuclei and mitochondria which give them their shape and make them more efficient to transport oxygen  Increase surface area  White Blood Cells aka leukocytes Maintain their nuclei and mitochondria Fight infections in the interstitial fluid

Blood Clotting  Platelets – small fragments of blood cells made in bone marrow  Blood Clotting Platelets adhere to the site where the blood vessel is damaged  Break apart and release substances called clotting factors Make other nearby platelets sticky and activate a series of reactions among other clotting factors in the plasma  Result in the formation of a protein called fibrin Fibrin threads trap red blood cells and additional platelets. This network of threads and cells builds up, eventually forming a patch that stretches over the torn tissue This patch dries into a scab.  Hemophilia

Check for understanding  In the margin list four main components of blood.  At the bottom of the page describe what you see in the picture below.  These are red blood cells. What might be the impact of RBCs this shape?