Category «Zoology»

Circulatory System – Blood Vessels

Blood Vessels • Blood vessels are intricate networks of hollow tubes that transport blood through the entire body. • Blood vessels (except capillaries) are made up of three layers – tunica externa, tunica media and tunica interna, surrounding the central blood carrying canal (known as lumen). – The tunica externa or tunica adventitia, strong outer …

Electrocardiogram-Blood Pressure and Blood Circulation

Electrocardiogram When the cardiac impulse passes through the heart,  electrical current also spreads from the heart into the  adjacent tissues surrounding the heart. A small portion of the current spreads all the way to the surface of the body. If electrodes are placed on the skin on opposite sides of the heart, electrical potentials generated …

Cardiac Cycle

Cardiac Cycle • Cardiac cycle is the term referring to all or any of the events related to the flow or pressure of blood that occurs from the beginning of one heart beat to the beginning of the next heart beat. • The contraction phase is called as systole while the relaxation phase is called …

Heart Beat and Pulse

Heart Beat To pump the blood into blood vessels, heart regularly contracts and relaxes in a rhythmic manner. It is known as ‘heart beat’. • Each heart beat includes one systole (contraction phase) and one diastole (relaxation phase) of the heart to distribute and receive blood to and from the body. The heart of a …

Cardiac Muscle Cells

Contractile muscles made from Cardiac Muscle cells • The cardiac muscle cells of the myocardium are arranged in layers that are tightly bound together (form syncytium) and completely encircle the blood-filled chambers. • There are dark areas crossing the cardiac muscle fibres called intercalated discs; they are actually cell membranes that separate individual cardiac muscle …

Cardiovascular System – The Heart

In large, multi cellular organisms, rapid transport of molecules over the long distances between internal cells and the body’s surface, and between the various, specialized tissues and organs is achieved by the circulatory system which includes a pump (the heart) a set of interconnected tubes (blood vessels or vascular system) and a mixture of extracellular …

Dense connective tissues

Dense connective tissue It contains tightly packed collagen fibres, making it stronger than loose connective tissue, and it is of two types : dense irregular tissue and dense regular tissue. You can find Connective Tissue Examples below. Dense irregular tissue has fibroblasts and many fibres (mostly collagen) that are oriented differently. This type of connective …

Muscular Tissue – Structure and Types

Muscular tissue It constitutes the muscles, made up of myocytes, (muscle cells) which are in the form of contractile fibres varying in lengths. Muscular tissue in general develops from the mesoderm of the embryo but the muscles of the iris of the eye and myoepithelial cells of the salivary, mammary and sweat glands arise form …

Types of loose connective tissue

Areolar tissue Structure: It takes the form of fine threads crossing each other in every direction leaving small spaces called areolae. It consists of ground substance, the matrix, white and yellow fibres and cells like fibroblasts, mast cells, macrophages (= histocytes or clasmatocytes), lymphocytes, plasma cells, mesenchyme cells, chromatophores. Fat cells can be seen in …

Blood

Blood Blood is a fluid which circulates in a closed system of blood vessels, in multicellular and highly complex vertebrate animals. Blood consists of a pale yellow fluid called plasma and solid elements such as red blood cells (erythrocytes) while blood cells (leucocytes) and platelets (thrombocytes). Composition Blood contains 55% of the plasma and 45% …