University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2019
Views:

269

Pages:

34
Author:

Quintin Ware

Lecture title : connective tissue Lecture Date : 25 / 3 / 2021 Connective Tissues • CT consists of three main components: cells, protein fibers, and ground substance. • Protein fibers + Ground substance = Extracellular matrix (ECM) secreted by CT cells ECM is the major component of most CT types • Consistency of CT varies from liquid, gel to solid. • • CT Does not occur on free surface. • CT has good nerve & blood supply EXCEPT cartilage & tendons SHEET NOTE #1 Connective tissue is consists of cells and extracellular matrix. The ECM is special in CT because it contains protein fibers + ground substance. The ECM in the ET exists as plasma membrane. The CT connects the tissues with each other . : Liquid as the blood , gelatinous(gelly like ) as connective tissue proper , solid as the bones , semisolid as cartilage .  The consistency of the CT is variable ( different from one type to another).     Majer compnents Connective tissue Epithelium tissue ECM cells Good blood supply except cartilage and tendons apascular doesn't occur on free surface Covering and lining any space Cells of Connective Tissue Fibroblast (active cell): more abundant and irregularly branched cytoplasm. nucleus is large, ovoid, euchromatic with prominent nucleolus. The cytoplasm has much RER and a well-developed Golgi apparatus. Produce and maintain ECM components Fibrocyte (quiescent cell) smaller elongated cell with fewer processes Darker oval nuclei (more heterochromatic) cytoplasm has less RER SHEET NOTE #2  The cells Fibroblast and Fibrocyte and Adipocyte are called permanent resident cells build the CT  Some cells emerge in the bone marrow then circulate in the blood then reach to different types of the body tissues… do its function and die > this type of cells that lives temprory and can live out of the CT called wandering or transient cells the permenant resident cells : 1. Fibroblast • active cells • most abundant type of the CT cells because it is the cell that produce and maintain ECM components in the CT ( main function ) • It has an irregular shape , branched cytoplasm , large ovoid nucleus . • The chromatin in it is euchromatin ( active cell ) • It has big amount of RER and well developed Golgi apparatus (It has similar properties of the active cells in the protein synthesis) The cells of CT wondering or transient cells macrophage WBC Mast cells Plasma cells permanent resident cells adipocytes fibrocyte Fibroblast Adipocytes: Very large cells have cytoplasmic rim & periphery nuclei (Signet ring appearance) Store fat Mast cells Oval or irregular shape cells cytoplasm are filled with basophilic granules Nucleus centrally located (often obscured) Produce chemical mediators e.g. histamine & heparin SHEET NOTE #3 2. Fibrocyte ( quiescent cell ) quiescent=inactive • This cell becomes smaller and elongated either fewer processes after being inactive. • The nucleus becomes darker because of the heterochromatin . • The RER less than the fibroblast. 3.Adipocytes • The last type of permanent resident cells • Large cell , has a single large fat droplet inside that pushes the nucleus and the cytoplasm to periphery . • the nucleus is flat • Its Signet ring appearance which caused by the dissolving of the fat while preparing the slide . • Main function : store fat permanent resident cells  . wondering or transient cells The wondering or transient cells : emarge from the bone marroe 1.Mast cells • We can see it in two shaped oval or irregular • The cytoplasm filled with basophilic granules • The nucleus is centrally located, some times it might be obscured and coverd because of the big amount of granules • Main function: produce chemical mediators as histamine & heparin Macrophage Different morphological features according to its activity & its location Nucleus eccentrically located (oval or kidney-shaped) Engulf bacteria & debris by phagocytosis Plasma cells Large ovoid cells, basophilic cytoplasm Nucleus eccentrically located (clock face appearance) -ve Golgi image Produce antibodies that fight against foreign substances WBC’s Will be discussed later SHEET NOTE #4 2.Macrophage • It has different shapes and names from tissue to anther (it depends on its function and where it is located ) • In central nervous system : called microglial plasma cells • In liver : called kupffer cells clock face • In lungs : called dust cells appearance • Large cell –ne Golgi image • Large and eccentrically nucleus • It has a clear lysosomes • Main function: Engulf bacteria & debris by phagocytosis 3.Plasma cells • Large and oval cell. • The nucleus has a clock face appearance because of the alternation between the hetero and euchromatin . • Because of producing antibodies (proteins ) the cytoplasm filled with RER (basophilic cytoplasm ) • Negative Golgi image . • Main function :Produce antibodies that fight against foreign substances. 4. WBC ( white blood cells ) Fibers of Connective Tissue Can be stretched Support Collagen Elastic Reticular (Bundles) (Anastomosing (Network Stain pink-red in H&E bundles form sheet Fibers) or lamina) Unstained in Poorly stained in H&E PAS +ve Tensile strength H&E Stains brown-black in Orcein or Resorscin Fuchsin stains black by silver stain (Argyrophilic) SHEET NOTE #5 *Type 1 of collagen *Elastic* Reticular : The types of the fibers : 1.Type 1 of collagen • Has a bundles shape in the CT • Gives the tissue a tensile strength • Stained pink-red in the H&E stain 2. • • • • protein fibers . •  Argyro means silver Elastic Consist of elastin protein Makes anastomosing bundles form sheet or lamina Gives elasticity for the tissue = can be stretched If the slides filled of elastic we can stain it by H&E stain : Orcein or Resorscin Fuchsin 3. Reticular fibers • Consist of type 3 collagen • Has a network appearance in the tissues • Supports the cells in the tissue • Unstained in H&E • You can use pas +ve /or any stain that contains silver ( it is Argyrophilic = loves silver ) Types of Connective Tissue Embryonic Connective Tissue Mesenchymal & Mucoid CT Connective Tissue Proper Loose & Dense CT Specialized Connective Tissue Reticular CT, Adipose Tissue, Cartilage, Bone & Blood Embryonic Connective Tissue Embryonic Connective Tissue is formed during the development of the embryo. Embryonic CT Mesenchyme CT Mucus CT Mesenchymal Connective Tissue • It is an early form of connective tissue found in embryos. • Mesenchyme is composed mainly of ground substance with few cells or fibers. • Mesenchymal cells differentiate into other cell types such as fibroblasts, fat, cartilage and bone. Mucoid Connective Tissue • Mucoid tissue is the principal component of the umbilical cord, where it is referred to as (Wharton’s jelly). • The umbilical cord normally contains two arteries and one vein embedded within connective tissue named Wharton's jelly. • Mucoid tissue is jellylike with sparse collagen fibers and scattered fibroblasts Connective Tissue Proper CT proper • Connective tissue proper is usually classified according to the amount of collagen and ground substance present. Loose CT Dense CT Loose Connective Tissues (Areolar) • Loose CT has roughly equal cells, fibers and ground substance. • It is flexible and NOT very resistance to stress. • Loose CT typically surrounds small blood vessels and nerves and can be found in the hypodermis, lamina propria. • Cell types = fibroblasts, plasma cells, macrophages, mast cells and a few white blood cells • All 3 types of fibers present • Gelatinous ground substance SHEET NOTE #6 • Can we find Mesenchymal Connective Tissue in adults ? Yes • In children we can find remains of the mesenchymal CT in the bulb of teeth Connective Tissue Proper This type of tissue is classified according to the amount of collagen and ground substance present. If the collagen is more than the ground substance its called Dense CT If the collagen equals the ground substance amount its called Loose CT 1) Loose CT • It is named as Areolar . • • • • The fibers , cells and the ground substance are equals . As a reason for the equal amount of collagen and other contents this tissue becomes loose ( Gelatinous ground substance ). It is flexible and NOT very resistance to stress (because of the low amount of collagen ) . This tissue is found:1. under the epithelium tissue • Lamina propria : loose CT rich in blood • • ( in the lamina propria ), 2.around the small blood vesels ,3.around the muscles , • • 4.around the nerves and 5.in the hypodermis . It contains all the cells types and the 3 types of fibers. supply under the epithelium we can find it in digestive , respiratory system and urinary • Hypodermis : it is a subcutaneous layer under the skin Dense Connective Tissue ● More bundles of type I collagen fibers over ground substance, fewer cells (mostly fibroblast). ● Protect organs & strengthen them structurally Types of dense connective tissue Dense irregular connective tissue Dense regular connective tissue SHEET NOTE #7 2) Dense CT • It has more bundles of type I collagen fibers over ground substance, fewer cells. • It protect organs & strengthen them structurally . Types of dense CT : (This classification depends on the arrange of the fiber bundles) Dense irregular connective tissue Dense regular connective tissue Dense Irregular Connective Tissue • Bundles of type I collagen appears randomly interwoven with no definite orientation. • Resistance to stress in all directions • Deep dermis of skin & capsules surrounding most organs. Dense Regular Connective Tissue • Consists mostly of type I collagen bundles & fibroblasts aligned in parallel. • Very strong & flexible • Providing great resistance to prolonged or repeated stress from the same direction. • Prominent in tendons, aponeurosis (sheet like tendons) and ligaments. • Have very few blood vessels (repair of damage is slow). • Yellow ligaments (along vertebral columns) contain beside collagen many parallel bundles of elastic fibers. SHEET NOTE #8 Types of dense CT : 1 ) Dense irregular CT Dense irregular CT is stronger than the regular one tendons aponeurosis tendons • Bundles of type I collagen appears randomly interwoven with no definite orientation • The random bundles make the tissue stronger because it can resist any stress force in any direction. • Very little amount of ground substance.(more fibers ) • Examples :dermis of skin ,capsules that surrounds the visceral organs . 2) Dense regular CT : ligaments bundles of collagen fiber elastic fibers • The type 1 collagen bundles & fibroblasts lined up(align) in parallel. • The fibers are more than the ground substance • Very strong & flexible. • Providing great resistance to prolonged or repeated stress from the same direction. • It is found in tendons, aponeurosis (sheet like tendons) and ligaments. • This tissue might have partial or complete tear if the force was so much more than normal • Have very few blood vessels ( few blood supply) • Yellow ligaments (along vertebral columns) contain beside collagen many parallel bundles of elastic fibers repair of damage is slow. Specialized Connective Tissue Reticular CT Adipose Tissue Cartilage Bone Blood Reticular Connective Tissue • In reticular tissue fibers of type III collagen form a delicate 3D network that supports various types of cells. • The fibrous network of this specialized CT is produced by modified fibroblasts called reticular cells • Reticular cells remain associated with and partially covering the fibers. • It is found in hemopoietic tissue and some lymphoid organs (bone marrow, lymph nodes, and spleen) SHEET NOTE #9 Types of Specialized CT : 1) Reticular CT It has reticular fibers that are composed of collagen type 3 which form a delicate 3D network that supports various types of cells. The reticular fibers consists of modified fibroblasts called reticular cells The reticular cells classified as modified fibroblasts because they have a different shape, these cells forms the fibers and envelope them Example : hemopoietic tissue/ and some lymphoid organs (bone marrow, lymph nodes, and spleen) lymphoid organs reticular CT hemopiteic T Adipose Tissue • Adipocytes: cells of adipose tissue (fat) • They are very large cells specialized for energy storage in lipid droplet(s) with triglycerides . • They are supported by reticular fibers, and connective tissue septa (divide the tissue into lobules of various sizes). • There are two types of adipose tissue: white and brown fat. SHEET NOTE #10 2) Adipose CT • It conceits of: fatty cells called Adipocytes + reticular fibers to support the cells + CT septa (divide the tissue into lobules of various sizes). • Adipocytes are large cells specialized for energy storage in lipid droplets with triglycerides. • There are two types of adipose tissue: white and brown fat. White vs. Brown adipose tissue White fat (have whitish to yellowish fat) Uninlocular: one large fat Droplet Brown fat (abundant mitochondria containing cytochrome pigment & abundunt blood capillaries Multilocular: many small fat droplets SHEET NOTE #11 White vs. Brown adipose tissue under the microscope Uninlocular & multilocular ‫تصنيف يعتمد على عدد قطرات‬ ‫الدهون في الخلية‬ Here we can notice the blood capillaries White fat This tissue has -a lot of large cells - each one of them filled with a single fat droplet which pushes the cytoplasm and -the flat nucleus to periphery It can be classified as uninlocular Brown fat The cells are -smaller –the nucleus is oval and centraly located – each cell filled with many small fat droplets It can be classified as multilocular White (unilocular ) adipose tissue • White fat is found in many organs throughout the body, typically forming about 20% of the body weight in adults. • Adipocytes of white fat are typically very large cells , ranging in diameter from 50 to 150 μm. These cells each contain primarily one large lipid droplet (they are unilocular ), causing the nucleus and remaining cytoplasm to be pushed against the plasma membrane. • Can be found in subcutaneous layer of skin, organ padding, and yellow marrow H&E Brown (multilocular ) adipose tissue • Brown fat comprises up to 5% of the newborn body weight but smaller amounts in adults. • Adipocytes of this tissue are typically smaller than those of white fat and contain primarily many small lipid droplets (they are multilocular ) in cytoplasm containing many mitochondria and a central nucleus. • In the newborn, it is located mainly in the back, neck, and shoulders. • In adults it is found ONLY in scattered areas, especially around the kidneys, adrenal glands, aorta, and mediastinum. PT SHEET NOTE #12 The white fat • It is more found in adults ( 20% of the body weight) • Can be found in subcutaneous layer of skin, organ padding as heart , and yellow marrow ( that is found in the medullary cavity of long bons in adults as femur, ulna and fibula ) • Adipocytes of white fat are typically very large cells , ranging in diameter from 50 to 150 μm The brown fat • It is more found in newborn babies (5% of their body weight ). • In adults it is found ONLY in scattered areas, especially around the kidneys, adrenal glands, aorta, and mediastinum. • It has a dark color because of the mitochondria.

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