body organization

• Endocrine glands include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands (suprarenal), pancreas, ovaries/testes, thymus, pineal gland, hypothalamus, and placenta.
• Hormones are chemical messengers produced by cells or organs, which travel through the blood to target tissues where they bind with specific receptors on cell surfaces.
• tissues are groups of cells that are similar in structure and working towards a common function
• 4 types of tissues

  • Epithelial tissue: covers body surfaces, lines body cavities and organs, and forms glands 
  • Connective Tissue: serves as a storage site for fat, plays an important role in immunity, and provides the body and its organs with protection and support  
  • Muscle Tissue: responsible for body movement and for movement of substances through the body
  • Nervous tissue: conducts nerve impulses from one part of the body to another
• Epithelium share two characteristics: basement membrane and free surface
• free surface

  may be specialized for protection, secretion, or absorption
• Basement membrane

  • a noncellular layer that binds epithelial tissue resist stretching 
• 3 basic types of epithelial tissues

  Squamous epithelium, Cuboidal epithelium, Columnar epithelium
• squamous - flat, thin, and covered with a layer of cells that are arranged in a single layer, reduces friction, makes diffusion easier
• Cuboidal epithelium: Found in many glands and in the lining of kidney tubules - they provide protection and are specialized for secretion and absorption - cube shaped cells
• Columnar epithelium: Small intestine is lined with them and they have a number of small, fingerlike folds on their exposed surface - this greatly increases the surface area for absorption, elongated , column-shaped cells and are specialized for absorption and secretion
• exocrine gland - Secrete their products into ducts leading to body surfaces, cavities, or organs 
• gland

  epithelial tissue that secretes a product
• • Exocrine gland: Secrete their products into ducts leading to body surfaces, cavities, or organs 
• Endocrine Gland: Lack ducts and secrete their products, hormones  into spaces just outside the cells 
• Connective Tissue: common role is the bind but it can also specialize in transport like blood and energy storage like adipose tissue
• connective tissue: connective tissues are composed of fibers (collagenous and/or elastic) embedded in an extracellular matrix containing ground substance (proteoglycans). The fibers may be arranged in parallel bundles or woven patterns.
• connective tissue matrix contains 3 types of protein fibers in different amounts depending on the type of connective tissue
• Collagen fibers: strong, ropelike and can withstand pulling because of their great tensile strength
• Elastic fibers: contain random coils and can stretch and recoil like a spring - common in
• Reticular fibers - thin strands of collagen that branch extensible forming extensively, forming interconnecting networks suitable for support soft tissue like liver and spleen -All of these are produced by fibroblasts - it also repairs tears in body tissues
• connective tissue proper - there are two main types
• loose connective tissue: there are two types - contains many cells but it has fewer loosely woven fibers and are in the matrix of the dense connective issue
• • Areolar connective - function as a universal packing material between other tissues and its many cells are embedded in a matrix mix that is soft and easily shaped Example: found between muscles where it permits one muscle to move freely over another, also anchors the skin to underlying tissues and organs
• Adipose tissue - contains cells that are specialized for fat storage 
• dense connective tissue forms strong bands because its large amount of tightly woven fibers
• dense connective tissue is found in

  ligaments, tendons, and the dermis
• there are 3 types of specialized connective tissue
• Cartilage: tough but flexible, it serves as cushioning between certain bones and helps maintain the structure of certain body parts - there are 3 different types 


  hyaline, elastic, fibrocartilage
• cells within the cartilage (chondrocytes) sit within spaces in the matrix called lacunae
• Cartilage is made up of protein fibers and somewhat gelatinous ground substance are responsible for the resilience and strength
• Cartilage lack blood vessels due to this nutrients are delivered through diffusion from nearby capillaries which makes the healing process slow
• Hyaline Cartilage Most common type and provides support and flexibility, Has a bunch of cartilage cells in a matrix of collagen fibers and a blush white, gel-like ground substance aka gristle
• hyaline cartilage is found at the end of long bones making it easier for the bones to connect to other bone
• elastic cartilage More flexible than hyaline cuz it has large amounts of wavy elastic fibers in its matrix, Found in the external ear where it provides strength and elasticity
• Fibrocartilage 


  contains fewer cells than either of the other two types, the matrix contains collagen fibers, and forms a cushioning layer in the knee joint as well as the outer part of the shock-absorbing disks between the vertebrae of the spine and it is made to withstand pressure
• Bone is makes up the skeletal system with cartilage and other competent of the joints
• Bone is a living, actively metabolizing tissue with a good blood supply that promotes prompt healing
• Bones has many functions like protection, support for internal structures, movement with the help of muscle, storage of lipids (in yellow marrow), calcium and phosphorous and the production of blood cells in the red marrow, matrix is secreted by the bone cells is hardened by calcium, enabling bone to provide rigid support
• Blood is specialized connective tissue consisting of a liquid matrix called plasma were formed elements like cells and cell fragments aka platelets