BSCI 201Review Sheet for Exam 2 A. Tissues:1. List, describe and give the function of the different types of Connective tissues.Common characteristics of connective tissue- All derived from the embryonic tissue, Mesenchyme- Exhibit a degree of vascularity (avascular poor vascularity highly vascular)- Composed of 2 partso The nonliving portiono The living portionThe nonliving portion – the extracellular matrix – composed of:- The ground substanceo Intertitial fluid – (“Tissue fluid”) extracellular fluid that surrounds cells within tissueso Cell adhesion proteins – act as molecular glue to attach cells to the matrix Fibronectin Laminano Proteoglycans – composed of protein core with glycosamino glycons (“GAGs”) attached. Increase in these materials result in an increase of the ground substance’s viscosity (ex: low viscosity would be runny potatoes, highviscosity would be harder potatoes). The GAGs are: Keratin sulfate Chondroitin sulfate Hyaluronic acido Ground substances can be fluid, solid, semi solid, and gel-likeThe living portion – is made of cells derived directly from Mesenchyme- There are 4 types of cells that secrete the 4 classes of connective tissueo 1. Fibroblasts secrete the connective tissue class – connective tissue propero 2. Chondroblast – secrete the class cartilageo 3. Osteoblasts – secrete the connective tissue class bone or osseous tissueo 4. Hematopoietic stem cells – secrete the class of connective tissue - blood- There are 3 types of extracellular matrix connective tissues o 1. Collagen Fibers: composed of the fibrous protein COLLAGEN. The collagen fibers are arranged in rope-like fashion, providing tensile strength (ability to withstand stress/pressure) to the connective tissue A collagen fiber is stronger than steel fiber. In freshly prepared connection tissue, the collagen fibers appear glistening white: collagenfibers are known as white fiberso 2. Elastic Fiber – “Yellow fibers” are composed of the fibrous protein ELASTIN. The elastin fibers exhibit the stretch-recoil property (under pressure the elastic fibers stretch to accommodate the pressure, but whenthe pressure is removed the elastic fibers recoil to assume regular shape and length) o 3. Reticular Fibers – composed of fine collagenous fibers that branch extensively to form networks. These fibers are abundant in areas where connective tissue abuts (is next to) other types of primary tissues. Ex: reticular lamina of the basement membrane1. Class: Connective tissue propera. Cells secreted: fibroblastsb. Consistency of the ground substance: gel-likec. 2 types of connective tissue properi. Loose CT1. 3 subtypesa. Areolar CT (“small open spaces”)i. Referred to as “Packing Material” because it surrounds cells in tissues of the body: interstitial fluidii. Gel like consistencyiii. Contains all 3 types of fibers (collagen, elastic and reticular)iv. Location: most widely distributed type of CT in the body and supports epithelial tissuesv. Basal Lamina of the basement membrane1. Ex: papillary layer of the dermis is areolarCTvi. Lamina Propria: surrounds tissues in the mucus membranesvii. Functions: 1. Cushioning of structures 2. Holds the interstitial fluid3. Plays role in inflammation by holding more interstitial fluid when edema (swelling) occurs at a sight of injuryb. Adipose CTi. “Chicken wire appearance”ii. Cells called adipose (fat cells) store triglycerides (neutral fat) which are able to expand to store more fat used for protection and insulationiii. As cells expand, the nuclei are pushed to the periphery of cell iv. Location: 1. Surrounds organs in the body 2. In the subcutaneous layer below the dermis v. Function: 1. Cushioning of organs2. Protects against trauma3. Holds organs in anatomical positiona. Ex: holds kidney against abdominal wall. Without the adipose capsule (like during anorexia) the body will catabolize the fat in the adipose capsule for energy. Gravity will cause the kidneys to drop, causing the urethra to twist and drain. This will result in kidney failure. 4. In the subcutaneous layer, the adipose CT acts as insulation to prevent heat lossc. Reticular Connective Tissuei. Contains reticular fibers ONLYii. The reticular fibers form networks within organs. The networks act as internal frameworks within the organs referred to as the STROMAiii. The stroma accommodate immune cells, which proliferate in the stroma of organs called the lymphoid organs (spleen, lymph nodes, thymus)ii. Dense CT1. Dense – because composed of many fibers – also referred to as FIBROUS CT2. 3 types:a. Dense regular CT – i. Made up of bundles of collagen arranged in a regular, orderly fashion parallel to the pull (stress)ii. Can withstand stress applied in one directioniii. Dense regular CT has elastic fibers because of its stretch recoil properties, however the stretch is limited by the opposition of the collagen fibers (not as flexible as elastic CT)iv. Location: 1. Ligaments: bind bones at the joint site2. Tendons: bind bone to skeletal muscle3. Flat like or sheet like tendons are referredto as apnevrosis b. Dense Irregular CT – i. Made up of thick bundles or collagen fibers facing in ALL DIRECTIONS (arranged in an irregular, haphazard manner)ii. Can withstand stress applied from different directionsiii. Located in the reticular layer of the dermisc. Elastic CT – i. Increased elastic fibers – stretch recoil properties ii. Location – ligaments connecting the intervertebral discsiii. Function – elastic CT is for stretching when under pressure and to rebound to its original size/shape when pressure is removed1. Ex: Ligaments flava – allow for the bending of the spinal cord (vertebral column). The vertebral column bounces back to its original length in an upright position. 2. Cartilage (second class of connective tissue)a. Secreted by chondroblastsb. Has a semi-solid ground substancec. Avasculard. There are 3 types of cartilage:i. Hyaline Cartilage1. Most abundant type of cartilage in the human body2. Many bones start off as hyaline cartilagea. **Forms the embryonic skeleton, which is ossified into bone tissue right before birth3. Location (post natal) – in the epiphyseal plates between the diaphysis of the epiphyses of long bonesa. The epiphyseal plates allow for longitudinal (linear) growth of long bonesb. The articular cartilage, which caps the end of an epiphysis. The articular cartilage acts as
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