Locomotion - Tissues Flashcards
4 Types of Tissue in Body
- Epithelial
- Muscular
- Nervous
- Connective
Epithelial Tissue
- Epithelial tissue is composed of cells laid together in sheets with the cells tightly connected to one another. Epithelial layers are avascular, but innervated.
- lining of glands, lining of surfaces
- Epithelial cells have two surfaces that differ in both structure and function.
- Glands, such as exocrine and endocrine, are composed of epithelial tissue and classified based on how their secretions are released.
- examples: glands (e.g. thyroid), hollow organs (e.g. duodenum), epidermis (skin)
Epithelium
A membranous tissue composed of one or more layers of cells that form the covering of most internal and external surfaces of the body and its organs.
Functions of Epithelium
Epithelia tissue forms boundaries between different environments, and nearly all substances must pass through the epithelium. In its role as an interface tissue, epithelium accomplishes many functions, including:
- Protection for the underlying tissues from radiation, desiccation, toxins, and physical trauma.
- Absorption of substances in the digestive tract lining with distinct modifications.
- Regulation and excretion of chemicals between the underlying tissues and the body cavity.
- The secretion of hormones into the blood vascular system. The secretion of sweat, mucus, enzymes, and other products that are delivered by ducts come from the glandular epithelium.
- The detection of sensation.
Muscular Tissue
(3)
- skeletal muscle (movement, locomotion)
- cardiac muscle (heart)
- smooth muscle (involuntary control- muscle in gut, muscle in blood vessels)
Nervous Tissue
- Nervous tissue or nerve tissue is the main tissue component of the two parts of the nervous system: CNS and PNS
- ANS e.g. autonomic ganglion
- CNS e.g cerebellum (brain)
- PNS e.g. nerve (sciatic nerve)
Connective Tissue
- tendon, bone, cartilage, and many more
- It supports and binds other tissues in the body
- Unlike epithelial tissue which has cells that are closely packed together, connective tissue typically has cells scattered throughout an extracellular matrix of fibrous proteins and glycoproteins attached to a basement membrane.
3 types of cartilage
- hyaline cartilage
- elastic cartilage
- fibrocartilage
Hyaline Cartilage
- Most abundant type of cartilage
- found as supportive tissues in the nose, ears, trachea, larynx, and smaller respiratory tubes
- As articular cartilage, hyaline is found as glossy covering on the articular surfaces of bones in synovial joints
Basic components of Tissue
- All body tissues have a cellular component and an extracellular component - the matrix
- Ratio of cells to matrix varies from tissue to tissue
—> Predominantly cellular tissue = e.g. liver
–> Predominantly ECM = e.g. hyaline cartilage
- hylaine cartilage has less nuclei under microscope
Synovial Fluid
- Is a connective tissue itself- like serum (the fluid that blood cells are suspended in)
- also called synovia, is a viscous, non-Newtonian fluid found in the cavities of synovial joints
- With its egg white–like consistency, the principal role of synovial fluidis to reduce friction between the articular cartilage of synovialjoints during movement
Loose Connective Tissue
- fascia if you pull up skin
- Loose connective tissue is the most common type of connective tissue in vertebrates
- It holds organs in place and attaches epithelial tissue to other underlying tissues
Dense Connective Tissue
- Dense connective tissue, also called dense fibroustissue, is a type of connective tissue with fibers as its main matrix element
- The fibers are mainly composed of type I collagen
- Crowded between the collagen fibers are rows of fibroblasts, fiber-forming cells, that generate the fibers
- tissue that has formed a full sheet (aponeurosis)
- epicranial aponeurosis is an example
Functions of ECM
(2)
*Why have so much ECM in connective tissues?
2 major functions of ECM:
1) Provide a scaffold to keep cells in an functional arrangement (liver-cells need to be held in place so still have ECM, but hyaline cartilage has a ton)
2) Distribute and dissipate forces (load) imposed on the body by posture and locomotion–> hyaline cartilage (absorb load)
* Connective tissues can (to varying degrees) modify their ECM to deal with load
• Adaptable to growth and exercise
- in knee joint –> hyaline cartilage, loading that joint, the tissue can absorb shock
What is ECM made of?
(3)
Combination(s) of:
- Water
- Complex macromolecules (e.g. collagens, elastin (stretchiness) and proteoglycans) that can variously resist tensile and compressive forces: macromolecules varies between different connective tissues
- Mineralised, inorganic matrix : a lot of mineralized tissue in bone, not other two
Examples: synovial fluid (96% water)-not much macromol., Hyaline cartilage (70% water)-A LOT of macro., compact bone (4% water)-not much macro.
Osteoclasts
- multinuclear
- a large multinucleate bone cell which absorbs bone tissue during growth and healing
- makes a pit in the bone and reabsorbs bone by using enzymes
Joints
and Tissues in an Organ
-Important to think of tissues working together as an organ
- An organ is a group of tissues that combine into a structural unit to perform a specific function
- Joint= connective tissues arranged into an organ: a joint actually is an organ
Example: Synovial Joint = bone, cartilage, synovial fluid, tendon, synovium
How do Cartilaginous Joints allow a little bit of movement?
Changes to the inter-vertebral disc induced by axial compression and bending
-disk is between two endplates of vertebrae –> has quite a fibrous outer ring and jelly/pulpy center
- this allows for flexion and extension in the spine and compression
- stand upright and you will be constantly compressing your spine
- bending forward: extension of posterior part of the disk and compression of anterior part
- a lot of intervertebral disks together produce a motion–> together they can produce big movements
