Transport in mammals Flashcards
What is the mammalian circulatory system?
A closed double circulation consisting of a heart, blood vessels and blood.
Structure of an artery
Each artery is a muscular tube lined by smooth tissue and has three layers: The intima, the inner layer lined by a smooth tissue called endothelium. The media, a layer of muscle that lets arteries handle the high pressures from the heart. The adventitia, connective tissue anchoring arteries to nearby tissues. They have very thick walls as blood flows at high pressure inside them.
Structure of a vein
consists of three main layers. The outer layer is connective tissue, called tunica adventitia or tunica externa; a middle layer of smooth muscle called the tunica media, and the inner layer lined with endothelial cells called the tunica intima. Thinner walls as blood flows in a very much lower pressure. 1.8 mm in diameter. 4 mm in diameter.
Structure of a capillary
Capillaries are very thin, approximately 5 micrometers in diameter, and are composed of only two layers of cells—an inner layer of endothelial cells and an outer layer of epithelial cells. They are so small that red blood cells need to flow through them single file. Very low pressure.
Relationship between the structure and function of arteries, veins and capillaries
Arteries transport blood away from the heart. Veins return blood back toward the heart. Capillaries surround body cells and tissues to deliver and absorb oxygen, nutrients, and other substances. The capillaries also connect the branches of arteries and to the branches of veins.
Structure of a red blood cell
The cell is flexible and assumes a bell shape as it passes through extremely small blood vessels. It is covered with a membrane composed of lipids and proteins, lacks a nucleus, and contains hemoglobin—a red iron-rich protein that binds oxygen.
Structure of a monocyte
The monocyte is a spherical cell with prominent surface ruffles and blebs.
Structure of a neutrophil
Neutrophils have a characteristic multilobed nucleus, with 3 to 5 lobes joined by slender strands of genetic material. The cytoplasm of neutrophils contains numerous purplish granules called azurophilic or primary granules that contain microbicidal agents.
Structure of a lymphocyte
Blood T and B lymphocytes are indistinguishable by light and electron microscopy. NK cells tend to be larger cells with relatively large granules scattered in their cytoplasm.
Differences between blood, tissue fluid and lymph
Whereas lymph is a colorless liquid, found mostly in the inter-cellular spaces of a tissue. Blood has RBC’s, WBC’s, platelets and a fluid called plasma. One of the major differences between them is that blood flows through blood vessels and lymph through lymphatic vessels.
Role of haemoglobin
Haemoglobin is essential for transferring oxygen in your blood from the lungs to the tissues.
Formation of haemoglobinic acid
The oxygen diffuses into the tissue cells and the haemoglobin acts as a buffer for the excess hydrogen ions, which it takes up to form haemoglobinic acid.
Formation of carbaminohaemoglobin
When carbon dioxide binds to hemoglobin, a molecule called carbaminohemoglobin is formed.
Significance of the oxygen dissociation curves
Only significant changes in the partial pressure of oxygen will result in significant changes to hemoglobin saturation. Relates oxygen saturation (SO2) and partial pressure of oxygen in the blood (PO2), and is determined by what is called “hemoglobin affinity for oxygen”; that is, how readily hemoglobin acquires and releases oxygen molecules into the fluid that surrounds it.
Significance of the higher red blood cell count of humans at high altitude
Pulse rate and blood pressure go up sharply as our hearts pump harder to get more oxygen to the cells. On returning to sea level after successful acclimatization to high altitude, the body usually has more red blood cells and greater lung expansion capability than needed.
