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.
Tissues in Musculoskeletal System
(9)
-bone, cartilage, tendon, ligament, joint capsule & synovium, Synovial fluid (tissue itself), loose connective tissue, dense connective tissue, skeletal muscle
Connective Tissues of the Musculoskeletal System
(8)
tendon, ligament, bone, cartilage, joint capsule and synovium, synovial tissue, loose connective tissue, dense connective tissue
NOTE: lots of ECM in those connective tissues
Bone
(ECM)
ECM:
- Organic component predominantly collagen
- Inorganic component hydroxyapatite (calcium and phosphate)-predominantly mineral
Bone
(cellular content)
Cells:
• Osteocytes (embedded in matrix itself)
- osteoclasts and osteoblasts (on surfaces of bones) maintain and remodel this matrix
-Remodelling occurs in response to load imposed on bone-can be good or bad remodeling–> need to keep bone stable
- osteoblasts, once they are absorbed by the matrix, become osteocytes
Osteoarthritis
- bone cell response to inflammed joint
- body responds to pain in joint by trying to stabilize it and lay down lots of bone
- can get out of control
- not necessarily painful, is actually stable
- but there will be a large loss of function, loss of motion
- Osteoarthritis is a condition that causes joints to become painful and stiff
- get synovial inflammation and degradation of cartilage
- get osteophytes (boney outgrowths)
Bone Remodelling
- Osteoblasts synthesize the organic matrix
- Osteoclasts are responsible for removing bone
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
Racing Greyhound Tarsus Fracture
(Cause)
Fracture of central tarsal bone of right hindlimb: differential load cycle on one side of the body from running anticlockwise in track–> lean into those corners
- 60% of all fractures
- Differential load distribution and load cycle : differential load from left side to right side
- extreme loading on that joint and hyperextension
- Anticlockwise running
- Most common in dogs that have been racing regularly
Remodelling of Tarsus Bone in
Greyhounds
(leading to fracture)
- generally poor remodelling
- remodelling of bone occurs in response to differential loading on one side of body
- there is regular spongy bone and then the gaps have been filled in by remodelling–> trying to stabilize the bone
- if you look closely you can see small cracks where remodelling has occured (microcracks)
- microcracks build up over time and the result is a fracture from loading
Fracture is end-stage pathology – bone shows microcracks and remodelling
What is a normal load for them will cause a fracture
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
Synovium
- The synovial membrane (also known as synovium or stratum synoviale) is a specialized connective tissue that lines the inner surface of capsules of synovial joints and tendon sheath.
- It makes direct contact with the synovial fluid lubricant, which it is primarily responsible for maintaining
Why have joints?
(function)
- allow for movement
- allow for growth
Various ways of joining bones together
(3)
- Fibrous (ex: sutures in skull)
- Cartilaginous ( ex: intervertebral disk) - connected entirely by cartilage –> allow more movement than fibrous joint, but less mobile than synovial
- Synovial (ex: metacarpophalangeal joint–> equivalent to our knuckle bone)
1. –> 3. = increasing range of motion and increasing complexity
Joints that allow for growth
Fibrous Joints!
- brain needs to grow in early life
- sutures are quite moveable in first stages of life
- become completely immovable in adult stage once brain has grown to size (in many cases)
Pelvic (pubic) Symphysis and intevertebral disk
(Cartilaginous Joint)
- usually fibrocartilage, but can be hyaline cartilage
- intevertebral disk is fibrocartilage
–> allows for some motion ( a little bit of motion)
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
Synovial Joints
(ex: shoulder joint)
- ball and socket joint (can move all the way round= circumduction)
- Circumduction is a combination of flexion, extension, adduction and abduction.
- Range of motion between two skeletal structures can be greatly increased when a joint contains a gap between them
- Synovial joint is characterised by a gap (joint cavity) filled with synovial fluid and hyaline cartilage covering boney ends
- Functional unit of several complex tissues- organs
Main Properties of Synovial Joints
Necessary properties:
• Allow movement (in one plane) can’t bend laterally or medially, but simultaneously contribute stability via:
- Ligaments (join bone to bone)-all helping with stability
- and Fibrous joint capsule (partly prevents lateral/medial movement)
- Load bearing & dissipation
- Complementary opposing surfaces - congruency (ex: patella sitting in the groove and femury patella ligaments holding it in midline it won’t luxate (dislocate))
- Generate sensory input to allow CNS control of movement–> patella region holds lots of nervous tissue- allows us to control movement to a fine degree
Rheumatoid Arthritis
- autoimmune reaction (body reacting against itself)
- Immune mediated destruction of articular cartilage
- Rheumatoid arthritis is an autoimmune disease that causes inflammation in your joints
Synovitis - inflammatory cell infiltration of synovium & synovial fluid (inflammation of the synovial membrane)
—> if you look at synovial fluid with rheumatoid arthritis you get tons of inflammatory cells (neutraphils)
Skeletal Muscle Injuries
(Gracilis muscle in greyhounds)
Gracilis muscle–> muscle on the inner thigh
- with injury you will see a lot of bad inflammation
- huge hematomas are quite typical with this as well (intramusclular and subcutaneous)
Gracilis Muscle Injury
(3 sites)
Three sites:
- muscular origin on pelvic symphysis (where muscle joins bone)
- tendinous insertion on crural fascia (tendon joins dense connective tissue)
- junction of muscle & tendon (myotendinous junction)
-you will find “weak points” between these junctions
