The Circulatory and Lymphatic systems

Blood Blood is a fluid that circulates throughout the body. It carries nutrients from digestive system to body cells. It carries oxygen taken up by respiratory system It removes wastes produced by cell metabolism. The human body contains approx 5-6L of blood. *

Blood consists of: A fluid component called plasma. And formed elements : Red blood cells White blood cells Platelets

Function of blood components Plasma : Makes up 55% of whole blood Is a yellowish liquid (mainly water) in which red blood cells, white blood cells and platelets are in suspension. Also contains nutrients, antibodies, hormones and metabolic waste .*

Red blood cells: Are concave on both sides and lack a nucleus Contain Hemoglobin (red pigment that carries oxygen) Are produced in the bone marrow 45% of blood volume *

Oxygenated blood carries oxygen and is bright red Deoxygenated blood depleted of oxygen, carrying carbon dioxide and is dark red (not blue). *

White blood cells: White blood cells protect the body by: Also called Leucocytes Are colourless Larger than red blood cells White blood cells protect the body by: Engulfing and digesting dead or damaged cells, old RBC’s, and microorganisms Produce antibodies to neutralize invading organisms *

Platelets: are red blood cell fragments Important in the clotting of blood (clotting –the process where the platelets clump together and start the formation of fibrin filaments to form a solid mass (a clot) and stop the bleeding) Fibrin filaments

The anatomy of the Circulatory System

The Heart

the heart has 4 chambers: Right and left atrium (1st chambers that blood enters in heart) Right and left ventricle (last chamber before blood leaves heart) ri Left atrium Right atrium Left ventricle (very muscular) Right ventricle

Major blood vessels of the heart Blood vessels are the plumbing of the body that assure the distribution of blood to the entire body. Two vessels leave the ventricles: The Pulmonary artery –blood is pumped to the lungs. The Aorta – blood is pumped throughout the body. Two vessels enter the atria: The Pulmonary veins – bring blood back from the lungs. The Venae Cavae – bring blood back from the body.

Main blood vessels Aorta (blood to body) Superior vena cava (blood from the upper body) Pulmonary artery (blood to the lungs) Pulmonary vein (blood from the lungs) Inferior vena cava (blood from the lower body) Septum

Blood Vessels

Arteries Arteries carry blood away from the heart to the organs of the body have thick, muscular, elastic walls to withstand high pressure. The Aorta is the largest artery in the body. These large arteries progressively branch and get smaller and smaller, becoming- arterioles, then capillaries. *

Capillaries Capillaries are minute branches at the ends of the arteries and veins. They are permeable allowing the diffusion of substances into all body cells which are within 50µm of a capillary. *

Veins Veins –go to the heart and have thinner walls and are less elastic than the arteries because there is less pressure. to help the blood to flow up from the extremities (e.g. legs), veins have one way valves that prevent backflow. Leg muscle contractions help “pump” the blood back to the heart. Capillaries turn into venules enlarging into veins returning to left atrium via the large Vena Cava. *

How it works

When a heart beats it first contracts the atria and then the ventricles Deoxygenated blood returns under pressure via the Vena Cava into the relaxed right atrium. Contraction of right atrium forces blood into the right ventricle. *

Ventricular contraction forces blood through the Pulmonary artery into the lungs. Blood travels through smaller arteries then arterioles and finally the capillaries in single file. The capillaries surround the minute air sacks (alveoli) and allow the exchange of gases (O2,CO2) between blood and inhaled air. *

Oxygenated blood leaves the capillaries of the lungs, first through the venules, then veins returning to the left atrium via the pulmonary vein. Contraction of the left atrium forces the blood into the left ventricle. *

Contraction of the left ventricle forces the blood through the Aorta throughout the body. Arteries branch off the aorta and supply various organs and tissues with oxygenated blood. The blood follows this path: Arterioles Capillaries – exchange of gases Venules Veins Vena cava *

Types of Circulation Pulmonary: the path followed by deoxygenated blood away from the heart to the lungs and then back to the heart as oxygenated blood Carbon dioxide diffuses out of the blood and into the alveoli and oxygen diffuses into the blood (gas exchange) Begins at the right ventricle, ends with the left atrium

Systemic: the circulation of blood to all parts of the body, except to the lungs. Transports oxygenated blood away from the heart to the rest of the body, and returns deoxygenated blood (CO2 rich) to the heart Gas exchange – O2 out of blood, CO2 into blood, occurs in the cells Begins in the left ventricle, ends with right atrium

Blood pressure Blood pressure is the force with which the blood is pushing against the arterial walls. Bp is measured in mm of mercury (mm Hg) The systolic pressure is when the ventricular pressure is at its maximum and the vessels are expanded. The diastolic pressure is when the heart is at rest ( no contraction). The pressure is given as a ratio of systolic 120 diastolic 80 (for adolescents normal bp is 113 mm Hg) 65 *

The lymphatic system Lymph is: Carries dissolved O2 and nutrients to the cells Collects cellular waste products plays an important role in the immune system Lymph is: A fluid that fills the spaces between the blood vessels and the body cells A fluid derived from the blood *

Lymphatic vessels resemble blood vessels and are close to them The lymph returns to the circulatory system via two veins near the heart. The lymph relies on muscle movement for circulation. *

The lymphatic system comprises of the following organs : The thymus- found underneath the heart The bone marrow- found in long bones (femur) The spleen- found left of stomach under diaphragm The tonsils- found in mouth bordering the pharynx *

The lymphatic vessels have lymph nodes throughout the body. When an infection occurs these nodes swell and harden (e.g. A cold or tonsillitis) *

Tonsils

The immune system The immune system is made of : The vessels and organs of the lymphatic system The white blood cells The ability of the body to protect itself against antigens is called immunity. Antigens are viruses, bacteria, abnormal cells or other substances that produce an immune reaction. *

The immune response can be An antibody is a substance produced by certain white blood cells that can neutralize specific antigens. The immune response can be specific non-specific. *

Non specific immune response The Non specific immune response is the body's ability to protect itself against any antigen. The skin acts as a barrier against antigens (bacteria, viruses, etc) and is involved in the non specific immune response. An example of a non specific immune response is getting picked by a thorn resulting in an infection. *

Specific Immune response The Specific immune response is the body's ability to protect itself against a particular antigen. Some white blood cells produce antibodies against particular antigens. Antibodies against the cold virus are not the same as ones against other bacteria. *

How antibodies work Bacteria (or viruses) invade the body Specific antibodies are produced by leucocytes Antibodies attach themselves to the bacteria white blood cell engulfs and digests bacteria * bacteria

Acquisition of immunity Immunity can be acquired in two ways: Naturally – by being exposed to an antigen ( diseases, etc) and contracting the disease. Your body produces antibodies that will protect you against that disease Vaccine – contains dead or weakened antigens that cause the white blood cells to produce antibodies against that disease. *

Blood groups Red blood cells have proteins on their surface, called antigens that provoke a clotting reaction when they are introduced into another body. Blood is grouped according to the type of antigen it contains and by the Rhesus factor. Blood typing is important for blood transfusions A blood transfusion is the injection blood products (usually red blood cells) from one person to another.

Blood type A -has the A antigen (protein) on its surface Blood type B -has the B antigen on its surface Blood type AB -has both A and B antigen on its surface Blood type O -has NO antigen on its surface

Rhesus (Rh)factor This Rh factor is another antigen determining the compatibility for blood transfusions Rh+ means the antigen is present Rh - means the antigen is not present

- A-, O- A+, A-, O+, O- B-, B+, AB-, AB+ B-, O- B+, AB+ B+, B-, O+, O- Blood Type can donate to can receive from + - A+, A-, AB+, AB- A-, O- A+, AB+ A+, A-, O+, O- B-, B+, AB-, AB+ B-, O- B+, AB+ B+, B-, O+, O- AB-, AB+ AB-, A-, B-, O- AB+ Universal recipient Universal donor O- O+, A+, B+, AB+ O+, O- Rh- Rh+ Rh- Rh+ Rh- Rh+ Rh- Rh+