The Circulatory System
All cells of our body require constant nutrition and waste removal
since they are metabolically active. Most of the body cells are located at
some distance from the nutrient sources such as the digestive tract and sites
of waste disposal such as kidneys. The cardiovascular system which
consists of the heart, blood vessels and blood, connects the various tissues
of the body. While the heart pumps the blood through the blood vessels, the
blood delivers nutrients and collect waste products.
Functioning of Human heart (Circulatory System)
Heart is a pumping organ. It receives blood from different parts of
the body through the veins that open through inferior and superior vena
cavae and pulmonary veins. While the right atrium receives deoxygenated
blood, the left atrium receives the oxygenated blood from the lungs. When
the wall of the atria contract the right and left atria pump the blood into the
right and left ventricles respectively. A pulmonary trunk arising from the
right ventricle takes away the blood to the lungs for oxygenation. The left
ventricle gives rise to an aorta, from which oxygneated blood is supplied to
the coronary arteries and the systemic circulation of the body. The blood flow between the right atrium and the right ventricle is
regulated by the tricuspid valve. The bicuspid or mitral valve regulates
the flow on the left chambers of the heart. In the pulmonary trunk and the
aorta, back flow of blood is prevented by a set of semilunar valves.
Origin and conduction of heart beat (Circulatory System)
During pumping action of heart, the heart muscles cause rhythmic
contraction and relaxation of the heart chambers in a specific sequence. The
rhythmic, sequential functioning of the cardiac chamber is maintained by
sino-atrial node (SA node), atrio-ventricular node (AV node), bundle of His
and Purkinje fibres.
The SA node situated in the upper, lateral wall of the right atrium is a
small, flattened strip of muscle fibre that is 1.5cm x 3mm in size. The fibres of
the SA node are closely associated with the muscles of auricles. SA node is
capable of generating action potential that can travel throughout the auricles.
The velocity of conduction is 0.3m/sec. The excitation from the SA node
stimulates the AV node. The AV node in turn conducts the stimulus to bundle
of His and Purkinje fibres. These myocardial fibres are found all over the
wall of the ventricles. In the conduction of stimulus through the AV node and
the fibrous system there is a delay in transmission.
Related Topics in Zoology:
Bio Zoology All Important Topics
- Human Physiology Introduction
- Nutrition
- Carbohydrates Poly hydroxyaldehydes (or) ketones
- Proteins (Polypeptides)
- Lipids
- Vitamins – Functions Of Vitamins
- Deficiency of Vitamin
- Minerals – Water – Role of water
- Balanced diet
- Obesity
- Digestive System
- Dental Caries (Tooth decay)
- Root Canal Treatment
- Peptic ulcer
- Hernia and Types
- Appendicitis (Appendix)
- Gall Stones
- Hepatitis
- Fractures – Types of fractures
- Mechanism of fracture
- Dislocation of joints
- Arthiritis
- Rickets and Osteomalacia – Orthopedics
- Muscles
- Mechanism of muscle contraction
- Types of muscle contraction
- Myasthenia Gravis
- Respiration – Process of pulmonary respiration
- Mechanism of Breathing
- Regulation of Respiration
- Pneumonia Tuberculosis Symptoms Treatment
- Bronchitis – Acute bronchitis, Chronic Bronchitis Causes
- Circulatory System – Functioning of Human heart
- Cardiac Cycle
- Coronary blood vessel and its significance
- Myocardial infarction
- Angina pectoris
- Angiogram – Angioplasty
- Atherosclerosis
- Heart block Echo cardiography Heart Valves
- Rheumatic Heart Disease (RHD), ICCU – (Intensive Coronary Care Unit)
- Blood Pressure
- Heart transplantation
- Pulse rate
- Cardio Pulmonary Resuscitation (CPR)
- Blood – Composition of plasma – Blood cells
- Clotting of Blood or Haemostasis
- Thrombosis
- Nervous system Co-ordination systems
- The Brain – Fore Brain, Midbrain, Hindbrain
- Memory
- Sleep – Types of sleep
- Stroke – Brain haemorrhage
- Alzheimer – Meningitis (Brain fever)
- Conditioned reflex
- Electroencephalography EEG
- Right and Left brain concept
- Spinal cord functioning
- Chemical co-ordination – Functions of Endocrine glands
- Hypothalamus
- Pituitary gland – hormone
- Hormones of Neurohypophysis – vasopressin
- Thyroid gland
- Parathyroid Gland
- Pancreas
- Adrenal gland
- Gonads
- Receptor Organs – Eye
- Photochemistry of Retinal visual Pigments
- Errors of refraction
- Optometry – Retinopathy
- Cataract – Lens Replacement – Glaucoma – Nyctalopia
- Eye Infections and Eye Care
- Ear
- Mechanism of hearing
- Defects of the ear
- Hearing Aid – Noise pollution
- Skin and functions of skin
- Melanin functions
- Effects of solar radiation / UV radiation – Skin grafting
- Dermatitis
- Tongue – Mechanism of Stimulation
- Excretion Ureotelism Nephron
- Mechanism of urine formation
- Renal Failure, Dialysis, Kidney Machines
- Kidney stone – Kidney transplantation
- Diabetes mellitus
- Functioning of male reproductive system
- Functioning of female reproductive system
- Ovulation and fate of the ovum – Menstrual cycle
- Fertilization
- Birth control