R. Brundage

A. Complex animals exhibit levels of organization.

1.A tissue is an aggregation of cells and intercellular substances which

function in one or more specialized activities (division of labor).

2.Various types of tissues can combine to form organs, such as the heart.

B. Animals are structurally and physiologically adapted to be able to:

1.Maintain internal operating conditions within some tolerable range.

2.Locate and acquire nutrients and dispose of wastes.

3.Protect themselves against injury or attack from viruses, bacteria, and

other agents.

4.Reproduce and often provide for the offspring during early development.

A.General Characteristics

1.Epithelial tissue is commonly called epithelium.

a.One surface is free (may have cilia or microvilli), and the other

adheres to a noncellular basement membrane.

b.Simple epithelium consists of a single layer of cells (squamous,

cuboidal, columnar); example: wall of capillaries.

c.Stratified epithelium consists of one or more layers of cells;

example: skin.

2.In epithelial tissues, cells are linked tightly together, with little intervening

material.

B.Cell-to-Cell Contacts

1.Epithelial cells adhere tightly to one another by means of special

attachment sites; this prevents leakage (example: stomach acid).

2.The types of junctions include: tight junctions, adhering junctions ("spot

welds"), and gap junctions (protein channels).

C.Glandular Epithelium

1.Glands are single cells or multicelled secretory structures.

2.Exocrine glands often secrete through ducts to free surfaces; they secrete

mucus, saliva, wax, milk, and so on.

3.Endocrine glands secrete hormones directly into intercellular fluid for

distribution by the blood.

A.Most connective tissue contains cells and fibers (collagen and/or elastin) secreted

by fibroblasts, all scattered in a ground substance.

B.Connective Tissue Proper

1.Loose connective tissue supports epithelia and organs and surrounds

blood vessels and nerves; it contains fibroblast cells and fibers plus

macrophages.

2.Dense, irregular connective tissue has thicker fibers and more of them,

but fewer cells; it forms protective capsules around organs.

3.Dense, regular connective tissue has its fibers in parallel; this is the

arrangement found in tendons (muscle to bone) and ligaments (bone to

bone).

C.Specialized Connective Tissue

1.Cartilage contains a dense array of fibers in a jellylike ground substance.

a.It cushions and maintains the shape of body parts; it resists

compression and is resilient.

b.Locations include the ends of bones, parts of the nose, external

ear, and disks between vertebrae.

2.Bone stores mineral salts, produces blood cells, and provides spaces for

its own living osteocytes.

a.Organized as flat plates and cylinders, bones support and protect

body tissues and organs; some have sites for blood cell

production.

b.Bones work with muscles to perform movement.

3.Adipose tissue cells are specialized for the storage of fat, which can be

used as an energy reserve and as cushions to pad organs.

4.Blood transports oxygen, wastes, hormones, and enzymes; it also

contains clotting factors to protect against bleeding and components to

protect against disease-causing agents.

A.Muscle tissue contracts in response to stimulation, then passively lengthens.

B.There are three varieties of muscle:

1.Skeletal muscle tissue attaches to bones for voluntary movement; it

contains striated, multinucleated, long cells.

2.Smooth muscle tissue contains spindle-shaped cells; it lines the gut,

blood vessels, and glands; its operation is involuntary.

3.Cardiac (heart) muscle is composed of short, striated cells that can

function in units.

A.Nervous tissue exerts the greatest control over the body’s responsiveness to

changing conditions.

1.Neurons are excitable cells, organized as lines of communication

throughout the body.

2.Neuroglia are diverse cells that protect and metabolically support the

neurons.

B.Various neurons detect stimuli; others coordinate the body’s responses; still others

relay signals to muscles and glands for response.

A.Overview of the Major Organ Systems

1.Eleven organ systems in vertebrates contribute to the survival of the living

cells of the body: integumentary, muscular, skeletal, nervous, endocrine,

circulatory, lymphatic, respiratory, digestive, urinary, and reproductive.

2.Each organ system contributes to the survival of all living cells of the

animal body.

B.Tissue and Organ Formation

1.Germ cells in the parental gonads produce either sperm or eggs by

meiosis; all other cells of the body are called somatic cells.

2.Fusion of gametes forms a zygote, which undergoes mitosis to form an

embryo.

3.Cells in the embryo become arranged into three primary tissues:

a.Ectoderm gives rise to skin and nervous system.

b.Mesoderm gives rise to muscle, skeleton, and the organs of

circulation, reproduction, and excretion.

c.Endoderm gives rise to the lining of the gut and its associated

organs.

A.Concerning the Internal Environment

1.The trillions of cells in our bodies must draw nutrients from, and dump

wastes into, the same fluid.

2.The extracellular fluid consists of interstitial fluid (between the cells and

tissues) and plasma (blood fluid).

3.The component parts of an animal work together to maintain the stable

fluid environment required by its living cells.

B.Mechanisms of Homeostasis

1.Homeostasis refers to stable operating conditions in the internal

environment, maintained through homeostatic controls.

2.Homeostatic control mechanisms require three components:

a.Sensory receptors detect specific changes in the environment.

b.Integrators (brain and spinal cord) act to direct impulses to the

place where a response can be made.

c.Effectors (muscles and glands) perform the appropriate

response.

3.A common homeostatic mechanism is negative feedback.

a.It works by detecting a change in the internal environment that

brings about a response that tends to return conditions to the

original state.

b.It is similar to the functioning of a thermostat in a heating/cooling

system.

4.Positive feedback mechanisms may intensify the original signal; sexual

arousal is an example.

A.Muscle tissue contracts in response to stimulation, then passively lengthens.

B.There are three varieties of muscle:

1.Skeletal muscle tissue attaches to bones for voluntary movement; it

contains striated, multinucleated, long cells.

2.Smooth muscle tissue contains spindle-shaped cells; it lines the gut,

blood vessels, and glands; its operation is involuntary.

3.Cardiac (heart) muscle is composed of short, striated cells that can

function in units.

A.Nervous tissue exerts the greatest control over the body’s responsiveness to

changing conditions.

1.Neurons are excitable cells, organized as lines of communication

throughout the body.

2.Neuroglia are diverse cells that protect and metabolically support the

neurons.

B.Various neurons detect stimuli; others coordinate the body’s responses; still others

relay signals to muscles and glands for response.

A.Overview of the Major Organ Systems

1.Eleven organ systems in vertebrates contribute to the survival of the living

cells of the body: integumentary, muscular, skeletal, nervous, endocrine,

circulatory, lymphatic, respiratory, digestive, urinary, and reproductive.

2.Each organ system contributes to the survival of all living cells of the

animal body.

B.Tissue and Organ Formation

1.Germ cells in the parental gonads produce either sperm or eggs by

meiosis; all other cells of the body are called somatic cells.

2.Fusion of gametes forms a zygote, which undergoes mitosis to form an

embryo.

3.Cells in the embryo become arranged into three primary tissues:

a.Ectoderm gives rise to skin and nervous system.

b.Mesoderm gives rise to muscle, skeleton, and the organs of

circulation, reproduction, and excretion.

c.Endoderm gives rise to the lining of the gut and its associated

organs.

A.Concerning the Internal Environment

1.The trillions of cells in our bodies must draw nutrients from, and dump

wastes into, the same fluid.

2.The extracellular fluid consists of interstitial fluid (between the cells and

tissues) and plasma (blood fluid).

3.The component parts of an animal work together to maintain the stable

fluid environment required by its living cells.

B.Mechanisms of Homeostasis

1.Homeostasis refers to stable operating conditions in the internal

environment, maintained through homeostatic controls.

2.Homeostatic control mechanisms require three components:

a.Sensory receptors detect specific changes in the environment.

b.Integrators (brain and spinal cord) act to direct impulses to the

place where a response can be made.

c.Effectors (muscles and glands) perform the appropriate

response.

3.A common homeostatic mechanism is negative feedback.

a.It works by detecting a change in the internal environment that

brings about a response that tends to return conditions to the

original state.

b.It is similar to the functioning of a thermostat in a heating/cooling

system.

4.Positive feedback mechanisms may intensify the original signal; sexual

arousal is an example.