Locomotion - Tissues

Question 1

4 Types of Tissue in Body

Answer 1

1. Epithelial
2. Muscular
3. Nervous
4. Connective

Question 2

Epithelial Tissue

Answer 2

• 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)

Question 3

Epithelium

Answer 3

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.

Question 4

Functions of Epithelium

Answer 4

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:

1. Protection for the underlying tissues from radiation, desiccation, toxins, and physical trauma.
2. Absorption of substances in the digestive tract lining with distinct modifications.
3. Regulation and excretion of chemicals between the underlying tissues and the body cavity.
4. 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.
5. The detection of sensation.

Question 5

Muscular Tissue

(3)

Answer 5

• skeletal muscle (movement, locomotion)
• cardiac muscle (heart)
• smooth muscle (involuntary control- muscle in gut, muscle in blood vessels)

Question 6

Nervous Tissue

Answer 6

• Nervous tissue or nerve tissue is the main tissue component of the two parts of the nervous system: CNS and PNS

1. ANS e.g. autonomic ganglion
2. CNS e.g cerebellum (brain)
3. PNS e.g. nerve (sciatic nerve)

Question 7

Connective Tissue

Answer 7

• 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.

Question 8

3 types of cartilage

Answer 8

• hyaline cartilage
• elastic cartilage
• fibrocartilage

Question 9

Hyaline Cartilage

Answer 9

• 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

Question 10

Basic components of Tissue

Answer 10

• 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

Question 11

Synovial Fluid

Answer 11

• 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

Question 12

Loose Connective Tissue

Answer 12

• 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

Question 13

Dense Connective Tissue

Answer 13

• 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

Question 14

Functions of ECM

(2)

Answer 14

*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

Question 15

What is ECM made of?

(3)

Answer 15

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.

Question 16

Tissues in Musculoskeletal System

(9)

Answer 16

-bone, cartilage, tendon, ligament, joint capsule & synovium, Synovial fluid (tissue itself), loose connective tissue, dense connective tissue, skeletal muscle

Question 17

Connective Tissues of the Musculoskeletal System

(8)

Answer 17

tendon, ligament, bone, cartilage, joint capsule and synovium, synovial tissue, loose connective tissue, dense connective tissue

NOTE: lots of ECM in those connective tissues

Question 18

Bone

(ECM)

Answer 18

ECM:

• Organic component predominantly collagen
• Inorganic component hydroxyapatite (calcium and phosphate)-predominantly mineral

Question 19

Bone

(cellular content)

Answer 19

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

Question 20

Osteoarthritis

Answer 20

• 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)

Question 21

Bone Remodelling

Answer 21

• Osteoblasts synthesize the organic matrix
• Osteoclasts are responsible for removing bone

Question 22

Osteoclasts

Answer 22

• 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

Question 23

Racing Greyhound Tarsus Fracture

(Cause)

Answer 23

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

Question 24

Remodelling of Tarsus Bone in

Greyhounds

(leading to fracture)

Answer 24

• 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

Question 25

Joints and Tissues in an Organ

Answer 25

-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

Question 26

Synovium

Answer 26

- 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

Question 27

Why have joints? | (function)

Answer 27

- allow for movement - allow for growth

Question 28

Various ways of joining bones together | (3)

Answer 28

1. Fibrous (ex: sutures in skull) 2. Cartilaginous ( ex: intervertebral disk) - connected entirely by cartilage --\> allow more movement than fibrous joint, but less mobile than synovial 3. Synovial (ex: metacarpophalangeal joint--\> equivalent to our knuckle bone) **1. --\> 3. = increasing range of motion and increasing complexity**

Question 29

Joints that allow for growth

Answer 29

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)

Question 30

Pelvic (pubic) Symphysis and intevertebral disk (Cartilaginous Joint)

Answer 30

- usually fibrocartilage, but can be hyaline cartilage - intevertebral disk is fibrocartilage --\> allows for some motion ( a little bit of motion)

Question 31

How do Cartilaginous Joints allow a little bit of movement?

Answer 31

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

Question 32

Synovial Joints | (ex: shoulder joint)

Answer 32

- 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

Question 33

Main Properties of Synovial Joints

Answer 33

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

Question 34

Rheumatoid Arthritis

Answer 34

- 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)

Question 35

Skeletal Muscle Injuries | (Gracilis muscle in greyhounds)

Answer 35

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)

Question 36

Gracilis Muscle Injury | (3 sites)

Answer 36

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