Chapter Four Cell and Tissue Structure

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Cell and Tissue Structure  Technicians must understand normal behavior and functioning of animals to care for them and help researchers.  Knowledge of normal anatomy and physiology will help technicians recognize abnormalities and report observed changes and become more valuable to the research team.

Anatomy and Physiology  Gross anatomy = structures visible to the eye  Histology = microscopic view of tissue  Physiology = function of parts of an organism  Functions to survive, grow & reproduce  Vertebrates have a spine made of bone  Anatomy & physiology reveals many species similarities  Species comparisons help develop animal models for the study of diseases.

Body Organization  Levels of organization: cellular, tissue & organ  Tissues composed of cells & intercellular material  Organs are composed of several types of tissue  Cells have three basic components:  cell membrane - surrounds, permits nutrients and gases to enter the cell, wastes to leave  nucleus - contains DNA that directs cell function  cytoplasm - contains nutrients & organelles  Some cellular processes are active and require energy, i.e. the breakdown of nutrients into their individual components  Other processes are passive & are result of concentration differences, i.e. passage of water across cell membrane

(Image) Types of Cells

Tissue  Four types of tissue and their functions are:  Connective tissue: binds together or supports cells, tissues and organs, i.e. bones, tendons and subcutaneous tissues.  Muscle = contractile tissue: shortens upon stimulation, to function in movement, posture and heat production.  Nerve tissue: specialized tissue that conducts impulses throughout the body. The brain, spinal cord are composed of nerve tissue.  Epithelial tissue: covers all body surfaces, lines all cavities and forms glands. It protects against the environment outside the tissue. Skin and the lining of the mouth are epithelial tissues.

Organs and Organ Systems  Organs make up systems that perform specific bodily functions.  Systems can not function alone and are dependant on others, i.e. the heart.  The heart is part of the circulatory system, pumps blood and composed of muscle, connective, nerve and epithelial tissues.  The nervous system controls the heart, using information from all the body.  Without the other parts of the circulatory system, heart would be unable to function.  The body consists of 11 major organ systems.

(Image) Imaging of Organs and Heart beat

Describing Anatomical Features  Terms may refer to the body  cranial = the head  Terms may refer to specific structures  oral = the mouth  Structures have names related to other structures  radial artery is named for its proximity to the radius.  Parts of the body have regional names  abdominal muscles

General Anatomical Organization  Bilaterally symmetrical  structures are the same on each side  body is divided evenly into right and left halves  Body arranged in 3 divisions  The head  contains sense organs and brain  protected by the skull  connects to the trunk by the neck  The trunk - thoracic cavity & abdominal cavity  The appendages - limbs & tail

Additional Reading Frandson, R.D. Anatomy and Physiology of Farm Animals, Fourth Edition. Lea and Febiger, Philadelphia, PA