More About Circulatory System 3D Model

Circulatory System1825

Circulatory System1825 Blood and lymph, the structure and working of the heart, blood vessels, circulation of blood (only names of the main blood vessels entering and leaving the heart, liver and kidney will be required).Circulatory System1825

Lymphatic system.

Circulatory System1825 Scope of Syllabus

• Composition of blood (structure and functions of RBC, WBC and platelets).
• A brief idea of tissue fluid and lymph.
• Increase in the efficiency of mammalian red blood cell due to absence of certain organelles; reasons for the same.
• A brief idea of blood coagulation.
• Structure and working of heart along with names of the main blood vessels entering and leaving the heart, the liver and the kidney.
• Concept of systole and diastole; Concept of double circulation.
• Brief idea of pulse and blood pressure.
• Blood vessels: Artery, vein and capillary to be explained with the help of diagrams to bring out the relationship between their structure and function.
• Brief idea of the lymphatic organs; spleen and tonsils.
• ABO blood group system, Rh factor.
• Significance of hepatic portal system.

CIRCULATORY SYSTEM AS THE TRANSPORT SYSTEM OF BODY

Circulatory System1825 Circulatory system is the system of internal transport in all the multicellular organisms. It supplies nutrients and oxygen to all the cells of body and removes waste products from them. It also transports hormones form the endocrine glands to their target organ and protect the body from the invasion of microbes.

Circulatory System1825 Components of Circulatory system

Circulatory System1825 The components of circulatory system are:

• Body fluids or circulatory medium – blood, lymph and tissue fluid to carry food, oxygen and other substances.
• Blood vessels and lymph vessels to carry the body fluids.
• Heart to pump blood though blood vessels.

BODY FLUIDS: BLOOD, LYMPH AND TISSUE FLUIDS

Body fluids in our body occur in three forms:

• BLOOD: It circulates though heart and blood vessels (arteries and veins).
• LYMPH: It flows though lymph vessels and lymphatic organ.
• TISSUE FLUID: It bathes the body cells. It is also called interstitial fluid or intercellular fluid.

Circulatory System1825 All the substances form blood to body cells and from body cells to blood pass though tissue fluid. Fig 8.1 shows the relationship between blood flowing though blood vessel, the tissue fluid around the cell and lymph in the lymph vessels. In close circulatory system as found in our body, blood flows through closed vessels. Their finest branches are capillaries which come closest to branches are capillaries which come closest to tissue cells. Plasma from blood diffuses out of the capillary wall and forms tissue fluid. The tissue fluid provides oxygen and nutrients to the cells. The carbon dioxide and waste products from the cells diffuse into the tissue fluid

Circulatory System1825 Apart of tissue fluid is absorbed by the lymph capillaries and forms lymph. It passes though lymph vessels and is poured into the subclavian vein.

https://byjus.com/biology/relationship-between-tissue-fluid-and-lymph/#:~:text=Lymph%20is%20a%20fluid%20flowing,system%20is%20known%20as%20lymph.

HEART – THE PUMPING ORGAN

Heart is a muscular pumping organ of the size of a first. It is a hollow, cone-shaped organ. It weight about 300 g in adult. It is situated almost in the chest between the two lungs. Its lower conical end is titled towards the left. It is enclosed in a bony cage formed of chest wall, ribs, backbone and breastbone. Circulatory System1825

Heart is enclosed in a sac called pericardium, formed of two pericardial membranes. The pericardial fluid present between the two pericardial members protects heart from injure and friction.

Heart Chambers

Circulatory System1825 Mammalian heart is four-chambered. It consist of two auricles or atria and two ventricles. The auricles. are demarcated form ventricles by an irregular groove, the coronary sulcus.

1. Auricles or Atria ( sing. Atrium) – The Receiving Chambers: The two thin-walled auricles are separated by a thin interarticular septum.

• The right auricle receives deoxygenated blood from the body by two large vessels (vena cavae).
• The left auricle receives oxygenated blood from lungs by two pairs of pulmonary veins.

2. Ventricles – The Distributing Chamber: The two thick-walled ventricles are separated by a thick and obliquely placed interventricular septum. Therefor, the left ventricle is somewhat large and walls are thicker than the right ventricle.

• The left ventricle supplies oxygenated blood to the entire body though a single aorta.
• The right ventricle supply deoxygenated blood to lungs though pulmonary aorta.

Circulatory System1825 The various apertures in the human heart are guarded by four valves.They maintain a unidirectional follow of blood inside the heart and into the great blood vessels.

• Cuspid Valves: Each atrium opens into the ventricle of its side by an atrio-ventricular aperture, which is aperture and allows blood to flow from left atrium to left ventricle. The bicuspid valve is also called mitral valve.
• A bicuspid valve is formed of two flaps or cusps (hence bicuspid). It guards the left atrio-ventricular aperture and allows blood to flow left atrium to left ventricle. The bicuspid valve is also called mitral valve.
• A tricuspid valve is formed of three flaps (hence tricuspid). It guards the Semilunar Valves: These are half moon-shaped or pocket-shaped flaps. They prevent the backflow of blood into the ventricles. right atrio-ventricular aperture and allows blood from right atrium to right ventricle.
• A set of three semilunar pulmonary valves guards the opening of right ventricle into the plumonary arota.
• A set of three semilunary aortic valves guards the opening of left ventricle into aorta.

Blood vessels Bringing Blood to Heart

• The right auricle receives deoxygenated blood from the body (except lungs) through.
• Superior or anterior vans cave or precavel which brings blood from head and upper regions of the body(i.e, chest and arms).
• The left auricle from rest of the body (i.e, from abdomen and legs).
• The left auricle receives oxygenated blood from from the lungs via four pulmonary veins.

Blood Vessels Leaving the Heart

• Pulmonary Aorta or Trunk: It arises from the right Ventricle and carries deoxygenated blood to the lungs for oxygenation. Its opening in the right ventricle is guarded by three semilunar pulmonary vavles.
• Aorta or Aortic Arch: It is the largest blood vessel that arises from the left ventricle and supplies oxygenated blood to the whole body except lungs. Its opening in the left ventricle is guarded by three semilunar aortic valves.

Blood Flow though Heart

• In the heart, oxygenated and deoxygenated blood remain completely blood remain completely separate.
• The deoxygenated blood from the entire body is returned to the right atrium by a superior or anterior vena cava and an inferior or posterior vena cave.
• The oxygenated blood from lungs is brought into the left atrium by four pulmonary veins.
• The two auricles contract and push blood into respective ventricles though right and left atria-ventricular apertures.
• The backward flow of blood from right auricle into the inferior vena cave is prevented by the Eustachian valve and into the coronary sinus by the the basics valve, present on the respective apertures. Also, the veins are always full of blood which offer resistance.
• Next, the two ventricles contract simultaneously.

1. From right ventricle, deoxygenated blood is pumped into pulmonary trunk.
2. From left ventricle oxygenated blood is pumped into the aorta. presence of cuspid valves on the artio-ventricular aperture prevents the back flow of blood into auricles.
3. The pulmonary trunk is divided into two pulmonary arteries. They carry deoxygenated blood from right ventricle to the lungs. The semilunar valves, present at the base of pulmonary trunk prevent return of blood into ventricle.
4. The aorta is the main distributing vessel. It branches into arteries and distributes blood to all parts of the body except the lungs.

HEARTBEAT AND CARDIAC CYCLE

working for heart include rhythmic contractions and relaxation of auricle and ventricle. The contraction phase is called systole and the relaxation phase is diastole. A heartbeat includes one systole followed by one diastole.

CARDIAC CYCLE

Cardiac cycle denotes the sequence of atrial and ventricular evens which occur once during each complete heartbeat. It is completed in about 0.8 seconds. It starts with the atrial systole and can be divided into following three phases

• Phase 1. The Atrial systole : It is simultaneous contraction of both the auricles. It lasts for about 0.1 to 0.15 second and pumps blood into the ventricles.
• Phase 2. The Ventricular systole: It is simultaneous contraction of both the ventricles. It lasts for about 0.3 second and pumps blood into the arteries.
• Phase 3. The joint Diastole : It is relaxation os both the chamber of auricle and ventricle. It is called general pause and is of about 0.4 second. During general pause, blood from vena cavae is poured into the right auricle and that of from pulmonary veins into left auricle.

PULSE RATE ( RATE OF HEARTBEAT)