The Study of Tissues

Tissues are typically preserved for study in chemicals called [1], sliced into thin histological [2], then mounted on a slide and colored with [3] to bring out contrast. A [4] section is a slice taken along the longest dimension of an organ, whereas a [5] section is taken perpendicular to this, across the shortest dimension.

All permanent tissues arise from three primary germ layers of the embryo. From the most superficial to the deepest layer, these are the [6-8]. Tissues are composed of cells embedded in nonliving matter called the [9]. The liquid that fills the spaces between the cells and fibers of a tissue is called the [10].

1._________________________ 6._________________________

2._________________________ 7._________________________

3._________________________ 8._________________________

4._________________________ 9._________________________

5._________________________10._________________________

Excitable Tissues

Skeletal muscle cells are often called [11] because they are so long and thin. They exhibit transverse light and dark bands called [12]. [13] muscle also has these bands, but differs from skeletal muscle in that it is not under voluntary control. It also exhibits [14] discs where cells meet end to end. These discs form mechanical and electrical linkages between cells. The third muscle type, [15] muscle, lacks the aforementioned bands. It is found in the walls of many internal organs. [16] muscle has multiple nuclei, while the other two types have only one nucleus per cell.

Nerve cells are also called [17]. Processes that transmit information toward their cell bodies are called [18], and a single process that transmits information away from the cell body is called the [19]. Nervous tissue also has a large number of supportive cells called [20].

11._________________________16._________________________

12._________________________17._________________________

13._________________________18._________________________

14._________________________19._________________________

15._________________________20._________________________

Embryonic and Fibrous Connective Tissues

In connective tissue the [21] occupy less space than the [22]. The latter consists of nonliving protein fibers and a featureless colloid called the [23]. The most common cells are [24], which produce the extracellular material. Large phagocytic cells called [25] develop from monocytes and also populate the connective tissues. White blood cells called [26] and many other cell types are also found in connective tissue. The fibers of connective tissue are of three kinds, [27-29]. Two of these types are made of varieties of [30], the most abundant protein in the body. The ground substance of connective tissue often has a gelatinous to stiff texture due to [31] molecules, which are polysaccharide chains called GAGs covalently bound to a core protein.

All permanent connective tissue comes from a gelatinous embryonic connective tissue called [32]. [33] tissue is a form of loose fibroconnective tissue found in nearly all tissue sections, and having an abundance of clear space filled with ground substance. Some fat cells, or [34], occur in this tissue type, but when these become the dominant cell type, the tissue is called fat or [35] tissue. Lymphatic organs and bone marrow have a spongy framework of [36] tissue, made of branching fibers and cells. Tendons are made of [37] connective tissue, so called because it consists mainly of densely packed, parallel collagen fibers. [38] connective tissue also contains densely packed collagen, but with fibers running in random directions. This type of tissue often forms a protective capsule around organs such as the spleen and testis.

21._________________________30._________________________

22._________________________31._________________________

23._________________________32._________________________

24._________________________33._________________________

25._________________________34._________________________

26._________________________35._________________________

27._________________________36._________________________

28._________________________37._________________________

29._________________________38._________________________

Supportive and Fluid Connective Tissues

The "gristle" of meat is a tissue called [39], which has chondrocytes occupying spaces called [40] amid a stiff matrix. If the fibers in this matrix are too fine to be seen in ordinary preparations and the matrix looks clear, the tissue is called [41]. Another type called [42] has an abundance of collagen fibers and is usually found where 41 overlaps with a tendon or ligament. A fibrous sheath called the [43] surrounds most cartilage, but is never found in type 42. Bone is also called [44] tissue. In a type called [45] bone, the cells and matrix are arranged in concentric lamellae around a central canal, which carries blood vessels and nerves. The bone cells found in these lamellae are called [46]. Bones are surrounded by a fibrous sheath called the [47].

The two fluid or transport tissues are [48] and [49]. The former consists of an amorphous ground substance called [50] and membrane-bound components collectively called [51], since some of them are not cells.

39._________________________46._________________________

40._________________________47._________________________

41._________________________48._________________________

42._________________________49._________________________

43._________________________50._________________________

44._________________________51._________________________

45._________________________

Epithelial Tissue

Epithelium is classified as [52] if it has only one layer of cells all resting on the basement membrane. If these cells are flat, it is called a [53] (two words) epithelium, which is the type best suited to rapid diffusion of solutes. One epithelium in class 52, called [54], looks multilayered because some of the cells are too short to reach the free surface, but all of them touch the basement membrane. When an epithelium truly consists of multiple layers of cells, and some cells rest on top of others instead of resting on the basement membrane, the epithelium is said to be [55]. The epidermis and vaginal surface have a type called [56] (two words) epithelium, but the epidermis differs from the vaginal lining because it is [57] to retard water loss and invasion by microorganisms. Multiple layers of rounded cells, seen in the ovaries and testes, form a [58] (two words) epithelium. Much of the urinary tract is lined by [59] epithelium, which is well adapted to stretching.

52._________________________56._________________________

53._________________________57._________________________

54._________________________58._________________________

55._________________________59._________________________

Intercellular Junctions, Glands, and Membranes

When it is important that matter not be allowed to seep between epithelial cells, the cells may be held together by a type of intercellular junction called a [60]. If two cells need to be attached to each other to withstand stress but do not need to be sealed all the way around, they are joined by [61], somewhat like rivets or spot welds between two pieces of metal. [62] junctions form channels between one cell and another that allow ions or other solutes to pass directly from the cytoplasm of one cell to the next.

[63] glands secrete their products directly into the blood stream; these products are chemical messengers called [64]. [65] glands, however, usually have [66] that convey their products to the body surface or the lumen of another organ. Many epithelia have mucus-secreting [67] cells, which are considered to be unicellular glands. Most glands, however, are multicellular. They have a connective tissue framework called the [68] and lobes and lobules of secretory tissue called the [69]. Glands are called [70] if they have unbranched ducts and [71] if their ducts branch. In many cases the secretory cells form a little sac called an [72] at the end of a duct. Mucous glands produce mucus, while [73] glands produce thinner, more fluid secretions. [74] glands release their products by exocytosis, while in [75] glands, the secretion consists of entire cells that have decomposed.

Body passages that are open to the exterior are lined by [76] membranes, which secrete mucus and protect the body against microbial invasion. They typically consist of an epithelium overlying an areolar tissue layer called the [77]. The body cavities and external surfaces of many viscera are lined with thin [78] membranes. Blood vessels are lined with a membrane called the [79]. The largest membrane of the body is the skin, or [80] membrane.

60._________________________71._________________________

61._________________________72._________________________

62._________________________73._________________________

63._________________________74._________________________

64._________________________75._________________________

65._________________________76._________________________

66._________________________77._________________________

67._________________________78._________________________

68._________________________79._________________________

69._________________________80._________________________

70._________________________

Tissue Transformations

Transformation from unspecialized cells to cells specialized for certain functions is called [81]. Tissue growth is called [82] if it results from multiplication of cells and [83] if it results from enlargement of preexisting cells. When a tissue transforms from one type of tissue to another, as from simple cuboidal to stratified squamous epithelium, it is said to undergo [84]. Shrinkage of a tissue from lack of use is called [85] (two words). The abnormal death of tissue is called [86]. Tissue death due to a lack of blood flow is called [87], and is the usual cause of heart attacks. [88] is a type of tissue death caused by anaerobic bacteria, which may produce bubbles of gas in the tissue. If a damaged tissue is replaced by the same kind of tissue, it is said to exhibit [89], but if it is replaced by scar tissue, it is said to show [90].

81._________________________86._________________________

82._________________________87._________________________

83._________________________88._________________________

84._________________________89._________________________

85._________________________90._________________________

Copyright ©1998 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use and Privacy Policy.
McGraw-Hill Higher Education is one of the many fine businesses of The McGraw-Hill Companies.
For further information about this site contact mhhe_webmaster@mcgraw-hill.com.