Adipocytes have small nuclei localized at the cell edge. Adipose tissue, or fat tissue, is considered a connective tissue even though it does not have fibroblasts or a real matrix and only has a few fibers. Adipose tissue is made up of cells called adipocytes that collect and store fat in the form of triglycerides, for energy metabolism. Adipose tissues additionally serve as insulation to help maintain body temperatures, allowing animals to be endothermic, and they function as cushioning against damage to body organs.
Under a microscope, adipose tissue cells appear empty due to the extraction of fat during the processing of the material for viewing, as seen in Figure 5. The thin lines in the image are the cell membranes, and the nuclei are the small, black dots at the edges of the cells. Blood is considered a connective tissue because it has a matrix, as shown in Figure 6.
The living cell types are red blood cells RBC , also called erythrocytes, and white blood cells WBC , also called leukocytes. The fluid portion of whole blood, its matrix, is commonly called plasma.
Figure 6. Blood is a connective tissue that has a fluid matrix, called plasma, and no fibers. Erythrocytes red blood cells , the predominant cell type, are involved in the transport of oxygen and carbon dioxide.
Also present are various leukocytes white blood cells involved in immune response. The cell found in greatest abundance in blood is the erythrocyte. Erythrocytes are counted in millions in a blood sample: the average number of red blood cells in primates is 4. Erythrocytes are consistently the same size in a species, but vary in size between species.
For example, the average diameter of a primate red blood cell is 7. Sheep erythrocytes are even smaller at 4. Mammalian erythrocytes lose their nuclei and mitochondria when they are released from the bone marrow where they are made.
The principal job of an erythrocyte is to carry and deliver oxygen to the tissues. Leukocytes are the predominant white blood cells found in the peripheral blood.
Lymphocytes function primarily in the immune response to foreign antigens or material. Different types of lymphocytes make antibodies tailored to the foreign antigens and control the production of those antibodies.
Neutrophils are phagocytic cells and they participate in one of the early lines of defense against microbial invaders, aiding in the removal of bacteria that has entered the body. Another leukocyte that is found in the peripheral blood is the monocyte. Monocytes give rise to phagocytic macrophages that clean up dead and damaged cells in the body, whether they are foreign or from the host animal.
Two additional leukocytes in the blood are eosinophils and basophils—both help to facilitate the inflammatory response. The slightly granular material among the cells is a cytoplasmic fragment of a cell in the bone marrow.
This is called a platelet or thrombocyte. Platelets participate in the stages leading up to coagulation of the blood to stop bleeding through damaged blood vessels. Blood has a number of functions, but primarily it transports material through the body to bring nutrients to cells and remove waste material from them. A pathologist is a medical doctor or veterinarian who has specialized in the laboratory detection of disease in animals, including humans. These professionals complete medical school education and follow it with an extensive post-graduate residency at a medical center.
A pathologist may oversee clinical laboratories for the evaluation of body tissue and blood samples for the detection of disease or infection. They examine tissue specimens through a microscope to identify cancers and other diseases. Some pathologists perform autopsies to determine the cause of death and the progression of disease. Improve this page Learn More. Skip to main content. Module Animal Diversity. Search for:. Connective Tissues Learning Outcomes Discuss the different types of connective tissues in animals.
Tendons attach muscle to bone while ligaments hold two bones together at joints. This tissue serves as the dermis of the skin, the submucosa of the digestive tract, capsules of organs, and tough sheets of fasciae called aponeuroses.
Elastic Connective Tissue : walls of arteries and lungs. This tissue contains wavy, thick elastic fibers which appear as though they can stretch as a rubber band. The expansion and recoil of these fibers are associated with air entering and leaving the lungs, with the propulsion of blood through large blood vessels, and with voice production in the vocal cords. When you observe the aorta, locate the parallel wavy branching elastic fibers, a few fibroblasts may be present.
In this preparation, there is smooth muscle cells present but not stained. Reticular Connective Tissue : forms stroma of liver, spleen, bone marrow, and lymph nodes. This tissue must be specifically stained and is usually taken from a lymph node or the spleen. These soft organs need an internal scaffolding called the stroma to hold them together. Reticular fibers provide most of the support for the liver and bone marrow as well. The reticular fibers can be described as delicate, heavily-branched, and dark, the matrix is similar to jello.
Adipose Tissue : surrounds heart and kidneys, subcutaneous tissue, and greater omentum. This is the most easily recognized tissue and will be found widely distributed in every organ microscopically studied this year. The cells are filled with the lipid, triglycerides , and the cytoplasm and nucleus are pushed to the periphery of the cell.
Triglycerides are your stored energy, and adipose cells act as good insulators and pillows. There is little matrix associated with adipose tissue but wispy collagenous fibers are threaded between the cells. Fibroblasts present in these fibers can become adipocytes. Draw and label Adipose Tissue from the Trachea slide :.
Hyaline Cartilage : costal cartilages, articular cartilage, ends of nose, trachea walls, and fetal skeleton. This is a tough, glossy, flexible tissue with many functions; it acts as the model for embryonic bone formation and then remains during bone growth as the epiphyseal plate; it is the articular cartilage covering the ends of bones to prevent friction; and it forms the costal cartilages between the first ten ribs and the sternum.
Hyaline cartilage prevents the collapse of the trachea as it forms the C-shaped supporting tracheal rings. If you twist the tip of your nose, you can test the resiliency and supportive function of this tissue. Hyaline cartilage has a semi-solid matrix composed of chondroitin which is promoted today as a miracle joint repair. Collagenous fibers are embedded in this matrix but are too thin to be seen. Because cartilage lacks a blood supply, nutrients are received through a membrane surrounding cartilage called the perichondrium.
The perichondrium is found in the right side of the picture below at the edge of the oval shaped cartilage. Elastic Cartilage : pinna of ear, eustachian tubes, and parts of larynx. If a tissue needs to be pliable yet strong, then adding elastic fibers to hyaline cartilage allows stretching with the return to original shape. The lacunae of elastic cartilage are more prominent and the presence of dark strands of elastic fibers embedded in the matrix.
Fibrocartilage : pubic symphysis, intervertebral discs, menisci of knee. Many knee problems involve the medial or lateral meniscus, or back problems may involve a slipped disc.
The tissue damaged is a fibrocartilage pad. Bone is a highly vascularized tissue. Unlike cartilage, bone tissue can recover from injuries in a relatively short time. Cancellous bone looks like a sponge under the microscope and contains empty spaces between trabeculae, or arches of bone proper. It is lighter than compact bone and found in the interior of some bones and at the end of long bones. Compact bone is solid and has greater structural strength. Blood and lymph are fluid connective tissues.
Cells circulate in a liquid extracellular matrix. The formed elements circulating in blood are all derived from hematopoietic stem cells located in bone marrow Figure.
Erythrocytes, red blood cells, transport oxygen and some carbon dioxide. Leukocytes, white blood cells, are responsible for defending against potentially harmful microorganisms or molecules. Platelets are cell fragments involved in blood clotting. Some white blood cells have the ability to cross the endothelial layer that lines blood vessels and enter adjacent tissues.
Nutrients, salts, and wastes are dissolved in the liquid matrix and transported through the body. Lymph contains a liquid matrix and white blood cells. Lymphatic capillaries are extremely permeable, allowing larger molecules and excess fluid from interstitial spaces to enter the lymphatic vessels.
Lymph drains into blood vessels, delivering molecules to the blood that could not otherwise directly enter the bloodstream. In this way, specialized lymphatic capillaries transport absorbed fats away from the intestine and deliver these molecules to the blood. View the University of Michigan Webscope to explore the tissue sample in greater detail. Visit this link to test your connective tissue knowledge with this question quiz. Can you name the 10 tissue types shown in the histology slides?
Connective tissue is a heterogeneous tissue with many cell shapes and tissue architecture. Structurally, all connective tissues contain cells that are embedded in an extracellular matrix stabilized by proteins. The chemical nature and physical layout of the extracellular matrix and proteins vary enormously among tissues, reflecting the variety of functions that connective tissue fulfills in the body.
Connective tissues separate and cushion organs, protecting them from shifting or traumatic injury. Connect tissues provide support and assist movement, store and transport energy molecules, protect against infections, and contribute to temperature homeostasis.
Many different cells contribute to the formation of connective tissues. They originate in the mesodermal germ layer and differentiate from mesenchyme and hematopoietic tissue in the bone marrow. Fibroblasts are the most abundant and secrete many protein fibers, adipocytes specialize in fat storage, hematopoietic cells from the bone marrow give rise to all the blood cells, chondrocytes form cartilage, and osteocytes form bone.
The extracellular matrix contains fluid, proteins, polysaccharide derivatives, and, in the case of bone, mineral crystals.
Protein fibers fall into three major groups: collagen fibers that are thick, strong, flexible, and resist stretch; reticular fibers that are thin and form a supportive mesh; and elastin fibers that are thin and elastic. The major types of connective tissue are connective tissue proper, supportive tissue, and fluid tissue. Loose connective tissue proper includes adipose tissue, areolar tissue, and reticular tissue. These serve to hold organs and other tissues in place and, in the case of adipose tissue, isolate and store energy reserves.
The matrix is the most abundant feature for loose tissue although adipose tissue does not have much extracellular matrix. Dense connective tissue proper is richer in fibers and may be regular, with fibers oriented in parallel as in ligaments and tendons, or irregular, with fibers oriented in several directions. Organ capsules collagenous type and walls of arteries elastic type contain dense irregular connective tissue.
Cartilage and bone are supportive tissue. Cartilage contains chondrocytes and is somewhat flexible. Hyaline cartilage is smooth and clear, covers joints, and is found in the growing portion of bones. Fibrocartilage is tough because of extra collagen fibers and forms, among other things, the intervertebral discs. Elastic cartilage can stretch and recoil to its original shape because of its high content of elastic fibers. The matrix contains very few blood vessels. Bones are made of a rigid, mineralized matrix containing calcium salts, crystals, and osteocytes lodged in lacunae.
Bone tissue is highly vascularized. Cancellous bone is spongy and less solid than compact bone. Fluid tissue, for example blood and lymph, is characterized by a liquid matrix and no supporting fibers. Under the microscope, a tissue specimen shows cells located in spaces scattered in a transparent background. Ligaments connect bones together and withstand a lot of stress.
What type of connective tissue should you expect ligaments to contain? One of the main functions of connective tissue is to integrate organs and organ systems in the body. Discuss how blood fulfills this role.
Blood is a fluid connective tissue, a variety of specialized cells that circulate in a watery fluid containing salts, nutrients, and dissolved proteins in a liquid extracellular matrix. Blood contains formed elements derived from bone marrow. Erythrocytes, or red blood cells, transport the gases oxygen and carbon dioxide.
Leukocytes, or white blood cells, are responsible for the defense of the organism against potentially harmful microorganisms or molecules. Some cells have the ability to cross the endothelial layer that lines vessels and enter adjacent tissues.
Nutrients, salts, and waste are dissolved in the liquid matrix and transported through the body. Why does an injury to cartilage, especially hyaline cartilage, heal much more slowly than a bone fracture?
A layer of dense irregular connective tissue covers cartilage. No blood vessels supply cartilage tissue. Injuries to cartilage heal very slowly because cells and nutrients needed for repair diffuse slowly to the injury site.
Skip to content The Tissue Level of Organization. Learning Objectives By the end of this section, you will be able to: Identify and distinguish between the types of connective tissue: proper, supportive, and fluid Explain the functions of connective tissues. Functions of Connective Tissues Connective tissues perform many functions in the body, but most importantly, they support and connect other tissues; from the connective tissue sheath that surrounds muscle cells, to the tendons that attach muscles to bones, and to the skeleton that supports the positions of the body.
Embryonic Connective Tissue All connective tissues derive from the mesodermal layer of the embryo see Figure. Classification of Connective Tissues The three broad categories of connective tissue are classified according to the characteristics of their ground substance and the types of fibers found within the matrix Figure. Connective Tissue Proper Fibroblasts are present in all connective tissue proper Figure. Connective Tissue Proper.
Fibroblasts produce this fibrous tissue. Connective tissue proper includes the fixed cells fibrocytes, adipocytes, and mesenchymal cells.
Connective Tissue Fibers and Ground Substance Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers. Loose Connective Tissue Loose connective tissue is found between many organs where it acts both to absorb shock and bind tissues together.
Adipose Tissue. This is a loose connective tissue that consists of fat cells with little extracellular matrix. It stores fat for energy and provides insulation. This is a loose connective tissue made up of a network of reticular fibers that provides a supportive framework for soft organs.
Dense Connective Tissue. Disorders of the…. Supportive Connective Tissues Two major forms of supportive connective tissue, cartilage and bone, allow the body to maintain its posture and protect internal organs. Cartilage The distinctive appearance of cartilage is due to polysaccharides called chondroitin sulfates, which bind with ground substance proteins to form proteoglycans. Types of Cartilage.
0コメント