Histo lab midterm

• Blood


  A unique form of connective tissue that consists of three major types of cells: red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
• Blood cells


  • Suspended in liquid medium called plasma
  • If removed from circulatory system, will clot and form a clear yellow liquid called serum
• Functions of blood


  Transport gases, nutrients, waste products, hormones, antibodies, cells, various chemicals, ions, and other substances in the plasma to cells in different parts of the body
• Erythrocytes (red blood cells)

  • Biconcave disks without nuclei, packed with the O2-carrying protein hemoglobin
  • Biconcave shape provides large surface-to-volume ratio, facilitating gas exchange
  • Lifespan of about 120 days
  • Normal concentration in blood is 3.9-5.5 million per microliter in women and 4.1-6 million in men
• Erythrocyte variations


  • Macrocytes - diameter more than 9 µm
  • Microcytes - diameter less than 6 µm
• Anisocytosis


  The presence of erythrocytes with great variations in size
• Leukocytes (white blood cells)


  • Involved in the cellular and humoral defense of an organism against foreign material
  • Lifespan of a few days
  • Normal count ranges from 6,000 to 10,000 per microliter of blood
• Leukocyte types


  • Granulocytes
  • Agranulocytes
• Granulocytes


  • Possess two types of granules: specific granules and azurophilic granules
  • Nuclei with two or more lobes
  • Include neutrophils, eosinophils, and basophils
• Agranulocytes


  • Do not have specific granules, but contain azurophilic granules (lysosomes)
  • Nuclei is round or indented
  • Include lymphocytes and monocytes
• Thrombocytes (platelets)


  • Nonnucleated, disk-like fragments 2-4 µm in diameter
  • Originate from megakaryocytes
  • Promote blood clotting and help repair gaps in blood vessel walls
  • Lifespan of about 10 days
  • Normal count ranges from 200,000 to 400,000 per microliter of blood
• Muscle tissue


  Composed of differentiated cells containing contractile proteins that generate forces for cellular contraction and movement
• Muscle tissue types


  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
• Skeletal muscle


  • Composed of bundles of very long, cylindrical, multinucleated cells with cross striations
  • Contraction is quick, forceful, and usually under voluntary control
  • Contraction is caused by the interaction of thin actin filaments and thick myosin filaments
• Cardiac muscle


  • Has cross-striations and is composed of elongated, branched individual cells that lie parallel to each other
  • Contains intercalated disks at sites of end-to-end contact
  • Contraction is involuntary, vigorous, and rhythmic
• Smooth muscle


  • Consists of collections of fusiform cells that do not show striations
  • Contraction process is slow and not subject to voluntary control
• Nervous tissue


  • The fourth basic tissue type of the body, organized into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)
  • Responds to stimuli and sends impulses to the central system, which then initiates other impulses to effector organs
• Neuron


  • The basic cell of the nervous system, consisting of the cell body, axon, and dendrites
• Spinal cord


  • Composed of grey matter (nerve cell bodies) and white matter (axonal projections)
• Brain


  • Composed of areas of grey and white matter, with an additional outer gray layer in some areas
• Cerebral cortex


  • Consists of six layers, from superficial to deep: molecular layer, outer granular layer, pyramidal cell layer, inner granular layer, internal pyramidal layer, and polymorphic cell layer
• Cerebellar cortex


  • Arranged into three layers: superficial molecular layer, deeper layer of Purkinje cells, and inner granular layer
• Meninges


  • The three connective tissue layers enclosing the brain: dura mater, arachnoid layer, and pia mater
• Glial cells


  • Derived from neuroectoderm, serve roles of connective tissue within the CNS: microglia, oligodendrocytes, and astrocytes
• Choroid plexus


  • Produces the cerebrospinal fluid, consisting of a tuft of capillaries surrounded by simple cuboidal epithelium
• Nerve fibers


  • Axonal projections travel in bundles through the body, encapsulated in fibroconnective tissue: epineurium, perineurium, and endoneurium
• Ganglions


  • Structures where multiple nerve fibers interconnect, containing large neuron cell bodies with Nissl substance and surrounded by capsule cells
• Circulatory system


  Consists of the blood and lymphatic vascular systems
• Components of the blood vascular system

  • Heart
  • Arteries
  • Capillaries
  • Veins
• Blood


  A unique form of connective tissue that consists of three major types of cells: red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
• Arteries


  • Efferent vessels that become smaller as they branch, carrying blood with nutrients and oxygen to tissues
  • Resist changes in blood pressure in initial portions and regulate blood flow in terminal portions
• Plasma


  The liquid medium in which the blood cells are suspended
• Arterioles


  • Tiny branches of arteries that lead to capillaries, under control of the sympathetic nervous system to regulate blood flow and pressure
• Blood clotting


  1. Blood is removed from the circulatory system

  2. It will clot

  3. The clot contains formed elements and a clear yellow liquid called serum, which separates from coagulation
• Capillaries


  • Tiny blood vessels, approximately 5-20 micrometres in diameter, where exchange of materials between blood and tissues occurs
• Functions of blood


  • Transport gases, nutrients, waste products, hormones, antibodies, cells, various chemicals, ions, and other substances to cells in different parts of the body
• Veins


  • Transport blood towards the heart, with valves to prevent reverse flow
  • Transport deoxygenated blood only (except pulmonary vein)
• Erythrocytes (red blood cells)

  Biconcave disks without nuclei, packed with the O2-carrying protein hemoglobin
• Layers of blood vessels

  • Tunica intima
  • Tunica media
  • Tunica adventitia
  • Vasa vasorum
• Erythrocytes


  • The biconcave shape provides a large surface-to-volume ratio, thus facilitating gas exchange
  • Macrocytes - Erythrocytes with diameter more than 9 µm
  • Microcytes - Erythrocytes with diameters less than 6 µm
  • Anisocytosis - Presence of erythrocytes with great variations in size