Chapter 9(connective Tissue) Flashcards
Connective tissue arises from
widely scattered free mesenchyme cells and is correspondingly ubiquitous in its distribution.
What is the function of Connective tissues?
bind structures together, form a framework and support for organs and the body as a whole, store fat, transport substances, protect against disease, and help repair tissue damage.
Connective tissues are characterized by
an abundance of intercellular matrix with relatively few cells.
Connective tissue is made up
of cells, ground substance and fibres.
what is the matrix?
The ground substance and the fibres together
Connective tissues ate different from epithelial tissues in that
its cells are not joined to form sheets.
_____ serves as a connecting system binding all other tissues together.
connective tissue
___ connect the skin to underlying tissues
- fascia
adipose tissue provides ______ from the skin.
insulation against heat losses
What is is responsible for the production of blood cells.
haemopoietic tissue,
connective tissue cells can be differentiated from one another by their___
varying amounts of extracellular matrix.
What tissue is particularly susceptible to shrinkage during fixation and why?
- Connective
- because of its mixed
composition of cells, fibres and matrix,
Connective tissue cells are usually divided into two groups based on their ability to move within the connective tissue namely
- Fibrocytes (or fibroblasts) and fat cells are fixed cells.
- Macrophages, monocytes, lymphocytes, plasma cells, eosinophils and mast cells are wandering cells.
What is the Most common cell type in connective tissue.
Fibrocytes
What is Considered the “true” connective tissue cell?
Fibrocytes
Which organelle is the main visible feature of fibrocytes in microscopy?
Flattened nuclei
______ connecting tissue cell lacks many organelles, indicating low activity
Fibrocytes
when does the Fibrocytes become active?
When Stimulated by tissue damage or other signals.
What is the active state of Fibrocytes called?
Fibroblasts
What are the components of the Fibroblasts?
Large, flat, and branching with a single oval nucleus.
Function of the fibroblast
Synthesize and secrete proteins (mainly collagen) to build and repair connective tissue.
What is the main function of adipocytes?
primary role is storing lipids, mainly as triglycerides.
What happens to the adipocytes When well-fed?
the cell cytoplasm becomes a thin rim around a single, massive lipid droplet, pushing the flattened nucleus to the edge.
the diameter of an adipocyte is
up to 100 micro meter
What happens to a “starving” adipocyte ?
may contain multiple small lipid droplets and gradually comes to resemble a fibrocyte.
Fat storage and mobilization are tightly controlled by:
- Nerves: Sympathetic nervous system plays a key role in mobilizing stored fat.
- Hormones: Insulin promotes fat storage, while glucagon and other hormones signal release.
Adipocytes secrete:
the protein leptin,
Function of protein leptin
signals the brain’s appetite centers about fat reserves.
Leptin deficiency can lead to
obesity in animal models
The total number of adipocytes is primarily determined by
the preadipocytes (or lipoblasts) generated during fetal and early postnatal development.
What are Reticular cells ?
These are specialized “fibrocytes” that build a supportive network of fibers within lymphoid organs, enabling proper organization and function of immune cells.
Function of reticular cells
- Forming a network of reticular fibers
- Providing support and organization
Fibrocytes posses nucleus which are _____ on the microscope
Large and slightly stained
Macrophages originate from precursor cells called
monocytes.
Monocytes develop in the
bone marrow and circulate in the bloodstream.
What are macrophages?
Macrophages are large cells with blunt cytoplasmic processes (extensions), small round nuclei (one per cell), and the ability to engulf and destroy foreign bodies (phagocytic).
In resting state, macrophages have ____
processes and are less mobile.
What happened during inflammation (active stage) in macrophages?
they retract their processes and become more amoeboid (able to change shape and crawl) for increased mobility.
What are mast cells?
Mast cells are plump cells with smaller nuclei and granular cytoplasm.
Function of mast cells
Present even in healthy tissues, constantly monitoring for potential threats.
How does mast cells response to potential threats?
they discharge the contents of their vesicles upon encountering antigens (foreign substances like bacteria or pollen),
What are the vesicles found in mast cells and their function?
- Heparin: They increase blood flow in close by vessels
- histamine vesicles: They increase the permeability of the vessel walls to plasma constituents and other white blood cells.
Description of Lymphocytes?
Smaller than average cells (6-8 μm) with a dark-staining, round nucleus. The cytoplasm forms a thin rim around the nucleus, making them inconspicuous in microscopy.
Lymphocytes are Primarily found in ?
connective tissue beneath the digestive tract epithelium
What happens when lymphocytes are triggered by immune reaction?
Some lymphocytes differentiate into specialized cells called plasma cells
Function of the plasma
producing antibodies, protein molecules that target and neutralize specific pathogens.
What are the changes that occur when monocytes differentiate into plasma
their cytoplasm expands significantly, and they become basophilic (staining blue with certain dyes). The nucleus has a distinctive “cartwheel” appearance due to the radial arrangement of chromatin material.
Plasma are located at;
the digestive tract tissues and lymphoid organs
Where does Eosinophilic Cells Develop?
in the bone marrow, similar to monocytes.
Description of Eosinophilic Cells
Large, round or oval cells with abundant bright red granules in their cytoplasm.
What is the Function of Eosinophilic Cells?
Enter inflamed tissues early on, phagocytosing (engulfing) immune complexes (antigens bound to antibodies).
What is a Epitheloid Cell?
When monocytes transform into macrophages and then arrange themselves in tightly packed sheets in chronic inflammation.
What gives rise to the cell types of the connective tissue?
Mesenchymal cells
Function of the mesenchymal cells
They may regenerate blood vessels or smooth muscle which have been lost as a consequence of tissue damage.
What are fibres
These are long thread-like products formed probably by the activities of the fibroblasts.
The three kinds of fibres are ?
collagenous or white, elastic or yellow and reticular .
What are the dominant fibre type in most connective tissues?
Collagen fibre
Which type of fibres are not elastic and resist stretching, maintaining tissue integrity under tension.
Collagen
Collagen fiber structure hierarchy includes
Bundles, Fibrils, Microfibrils, tropocollagen
There are how many known types of tropocollagen?
21
What type of collagen fibre plays a crucial role in the structure of the basal lamin
Type IV
What type of fibre are the backbone of connective tissues, offering remarkable strength and support.
Collagen fibers
Collagen fibre types differ in their content of
the amino acids hydroxyproline and
hydroxylysine and amount of carbohydrates attached to the collagen molecules.
What are the major fibre-forming tropocollagens.
Types I, Il and Ill
Microscopic observation of elastic fibre requires special stains like
resorcin fuchsin to highlight their presence, as they lack visible substructure under simple light microscopy.
Which types of fibre are light yellow?
Elastic fibre