A structure formed by a combination of two or more basic tissues
Organ system
Several organs with similar functions grouped together
Organ classification based on morphology
Tubular
Parenchymatous
Tubular organ
A hollow organ with a lumen (canal) and a wall
Layers of the tubular organ wall
Tunica mucosa
Tunica submucosa
Tunica muscularis
Tunica adventitia or Tunica serosa
Tunica mucosa
Composed of lining epithelium, lamina propria and lamina muscularis mucosae
Kept moist by secretions from lining epithelial or glandular cells
Tunica submucosa
Composed of loose connective tissue, contains blood vessels, nerves, autonomic ganglia and nerve plexuses
Tunica muscularis
Generally composed of two layers: inner thick circular and outer thin longitudinal smooth muscle
Tunica adventitia or Tunica serosa
Outermost coat composed of loose connective tissue with blood vessels, nerves, myenteric ganglia and plexuses, and adipose cells
Parenchymatous organ
A solid organ composed of a stroma and a parenchyma, where the parenchyma is the functional part of the organ
Major body systems
Musculoskeletal system
Nervous system
Cardiovascular system
Lymphatic system
Integumentary system
Respiratory system
Urinary system
Digestive system
Endocrine system
Reproductive system
Special sense organs
Musculoskeletal system
Composed of skeletal muscles, bones, joints, tendons and nervous structures that support and move the body
Bone
Gives support to the body and serves as a point of attachment for muscles, site of calcium deposition and withdrawal
Bone classification by shape
Tubular
Flat
Long bone
Tubular bone that forms the skeletal framework of the limbs, composed of diaphysis, metaphysis, epiphyseal plate and epiphysis
Epiphyseal plate
A narrow zone of growth that separates the metaphysis from the epiphysis, where cartilage is replaced by bone through endochondral ossification
Short bone
Has the same structure as the long bone except that it has no epiphyseal plate
Flat bone
Makes up the bones of the skull/cranium, pelvis and shoulder blade, develops by intramembranous ossification
Muscle organ or Anatomic muscle
A parenchymatous organ composed of muscle fascicles (bundles), can only contract not relax
Scapula
Shoulder blade
Intramembranous ossification
Bone development process
Flat bones
Shaped like a sandwich, made up of two layers of compact bone separated by a layer of cancellous bone
Initially the wall and the middle region are occupied by cancellous bone
As development progresses the cancellous wall becomes compact by addition of more lamellae in the existing bone trabeculae
The intertrabecular spaces in the cancellous middle region become marrow cavities filled with red bone marrow
Syndesmosis
Connective tissue joining adjacent flat bones, particularly in the skull
Fontanelle
Wide suture where three or more flat bones meet
Muscle organ or Anatomic Muscle
Muscles studied in gross anatomy, can only contract not relax, paired so one contracts while the other is passively extended
Muscle organ
Composed of muscle fascicles (bundles)
Each muscle fascicle consists of several skeletal myocytes/fibers arranged parallel to each other
Presents three gradations of connective tissue investment that transmit the force of contraction: epimysium, perimysium and endomysium
Epimysium
Irregular DWFCT capsule that enwraps the whole muscle organ, attached to the end points at which the muscle originates or inserts on bone
Perimysium
Connective tissue layer made up of a sheath of collagen fibers that encloses a muscle bundle or muscle fascicle
Endomysium
Delicate loose connective tissue sheath with collagen and reticular fibers that encloses individual skeletal myocytes (or muscle fibers)
Structures Associated with Bone and Muscle Organs
Tendon
Joint or articulation
Afferent nerve endings
Efferent nerve ending
Tendon
Composed of regular DWFCT that attaches muscle organ to bone organ, has tremendous tensile strength, encapsulated by an irregular DWFCT called epitenon
Tendon
Consists of bundles of collagen fibers, which correspond to muscle fascicles
Each bundle is enclosed by a perimysial-like connective tissue called, endotenon
Anchored to the bone by fibrous bone sheaths called annular ligaments
Separated from the annular ligament by a sheath of loose connective tissue, adipose tissue or synovial sheath called paratenon or paratendon
At points of friction the tendon is wrapped in a synovial sheath
Nervous system
Complex of organs formed by nervous tissue, connective tissue, and vascular components
Sharpey's fibers
Ends of collagen fibers embedded in the bone or cartilage to achieve actual attachment of the tendon
Nervous tissue
Tissue that exhibits two properties: irritability (ability to react) and conductivity (ability to transmit the elicited response)
Nervous system
Composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (all other nervous tissue)
Joint
Structures that unite two or more bones together, provided for weight-bearing, locomotion, stability, and growth
Tissues that may contribute to articulations
Hyaline cartilage
Fibrocartilage
Dense collagenous tissue
Loose collagenous tissue
Bone
Adipose tissue
Development of the nervous system
1. Specialized region of surface ectoderm along the dorsal midline thickens to become neural ectoderm
2. Neural folds form and lips fuse to become the neural tube
3. Neural tube is incorporated into the developing embryo to form the brain and spinal cord
4. Neural crest cells remain separate from the neural tube and form the peripheral nervous system