Tissues, Organ Systems and Homeostasis

Dr. A. Russo-Neustadt

Biology 155

Organization of the Animal Body

• Animals’ bodies exhibit hierarchical organization –– Biological molecules are organized into

organelles (ex. Phospholipids and proteins are arranged into the plasma membrane)

– Organelles are organized into a cell (ex. Nucleus + plasma membrane + cytoplasm proper + many organelles = cell)

Organization of the Animal Body (continued)

• Hierarchical organization continued –– Groups of similar cells are organized into tissues (ex.

Cardiac muscle cells are organized into the tissue, cardiac muscle); Note that the evolution of multicellular living forms required development of tissues

– Two or more tissues are organized to form an organ (ex. Cardiac muscle tissue + connective tissue + epithelial tissue = the heart; provides force to move blood)

Organization of the Animal Body (continued)

• Hierarchical organization continued –– Organs are organized into organ systems (ex.

Heart + blood vessels + blood = cardiovascular system; function is transport)

– Organ systems are organized into an organism

(ex. An animal consists of 11 organ systems)

Embryonic Tissues – all adult tissues are derived from one of

three embryonic tissues

gut

Ectoderm = “outside skin”

Endoderm = “inside skin”

Mesoderm = “middle skin”

Cross section through embryo

Animal embryo

Fate of Embryonic Tissues

• Ectoderm will become the outer covering of the body and the nervous system

• Mesoderm will become the muscles and internal skeletons

• Endoderm will become the lining of the gastrointestinal tract, lungs, vessels and ducts

Adult Tissues

• Definition = groups of cells with similar structure, embryonic origin, and function; cells are bound together by extracellular material and function together to perform a specific task

• There are four main types of adult tissues in the animal body

Epithelial Tissues

• Source = may be derived from any tissue in the embryo

• Function = mainly protective, therefore they cover all free surfaces of the body; can be specialized for absorption, excretion, secretion, etc.

Epithelial Tissues (continued)

• Characteristics = – Closely joined cells with little extracellular

material between the cells– Presence of a basement membrane secreted by

the epithelial cells; separates the epithelial cells from underlying tissues

– One free surface not in contact with other cells

Fig. 20.4

Epithelial Tissues (continued)

• Classification = ask and answer two questions– How many cell layers above the basement

membrane?• Simple = one layer of cells; used for exchange (ex.

Diffusion of gases in the alveoli of the lungs, absorption in the small intestine; see previous slide)

• Stratified = more than one layer of cells; used for protection (ex. the outer layer of the skin)

Epithelial Tissues (continued)

• Classification continued –– What shape are the cells? (when viewed from the side)

• Flat and thin = squamous; used to maximize diffusion (non-energy requiring exchange where things move from an area of high to an area of low concentration); ex. Alveoli of lungs, capillaries

• Look like squares = cuboidal; used to maximize energy requiring exchange such as absorption and excretion (things can move from an area of low concentration to an area of high concentration); ex. respiratory system

• Tall and thin = columnar; as cuboidal above; ex. Small intestine

Fig. 20.4

Connective Tissues

• Source = may be derived from any tissue in the embryo

• Function = many, but generally holds things together in the body; can be specialized to give structure to and protect body parts

Connective Tissues (continued)

• Characteristics =– Few cells

– Lots of extracellular material between the cells; extracellular material is produced by the cells and is called matrix

– Matrix consists of –• Protein fibers

• Ground substance = non-fibrous proteins + other molecules

• Fluid

Fig. 20.5

Connective Tissues (continued)

• Classification = ask and answer one question– What is the nature of the extracellular matrix?

• Fluid = tissue is blood, functions in gas transport

(Matrix)

Connective Tissues (continued)

• Classification = ask and answer one question– What is the nature of the extracellular matrix?

(continued)• Solid =

– Mainly protein fibers = connective tissue proper (ex. Loose and dense connective tissues, adipose)

– Protein fibers + ground substance = special connective tissues (ex. Bone and cartilage)

Fig. 20.5

Muscle Tissues

• Source = derived from the embryonic mesoderm• Function = allows movement of the body or

movement within the body• Characteristics =

– Closely joined cells with little extracellular material

– Contain specialized protein fibers capable of contraction

Fig. 20.6

Muscle Tissue (continued)

• Classification –– Cardiac Muscle = heart muscle

• One, centrally located nucleus

• Presence of striations

• Short, branched cells

• Presence of intercalated discs

• “involuntary”

Fig. 20.6

Muscle Tissue (continued)

• Classification –– Skeletal Muscle

• Many, peripherally located nuclei

• Presence of striations

• long, thin cells

• “voluntary”

Fig. 20.6

Muscle Tissue (continued)

• Classification –– Smooth Muscle – found in “hollow organs”

• One, centrally located nucleus

• no striations

• Short, tapered cells

• “involuntary”

Fig. 20.6

Nervous Tissue

• Source = derived from the embryonic ectoderm• Function = communication• Characteristics –

– Electrically excitable cells (neurons with cell body and processes), or

– Cells that support, nourish and protect the neurons (glia)

• Classification = none

Fig. 20.7

Animal Organ Systems

System Major Component

Function

Integumentary Skin External Protection

Skeletal Bones Support

Muscular Skeletal Muscles

Movement

Fig. 20.10

Animal Organ Systems - continued

System Major Component

Function

Nervous Brain and Nerves

Integration

Endocrine Endocrine Glands

Integration

Circulatory Heart and Blood Vessels

Transport

Fig. 20.10

Animal Organ Systems - continued

System Major Component

Function

Respiratory Lungs or Gills Gas Exchange

Digestive Gastrointestinal Tract

Nutrient Acquisition

Urinary Kidneys Waste Elimination

Fig. 20.10

Animal Organ Systems - continued

System Major Component

Function

Reproductive Ovaries and Testes

Production of New Individuals

Immune White Blood Cells and Lymph Glands

Internal Protection

Fig. 20.10