A&P chapter 1

Anatomy

Studies the structure of body parts and their relationships to one another.

Physiology

Concerns the function of the body, in other words, how the body parts work and carry out their life sustaining activities. Often focuses on cellular and molecular level.

Gross or Macroscopic Anatomy

Study of large body structures visible to naked eye (ex: heart, lungs, kidneys).

Regional Anatomy

All structures in a particular region of the body, ex: abdomen, leg

Systemic Antomy

Body structure is studied system by system, ex: cardiovascular system, you would examine the heart and blood vessels of the entire body.

Microscopic Anatomy

Deals with structures too small to be seen with the naked eye.

Cytology

Studies cells of the body.

Histology

Studies microscopic tissues of the body.

Developmental Anatomy

Traces structural changes that occur throughout the life span.

Embryology

Subdivision of developmental anatomy, concerns developmental changes that occur before birth.

Principle of complementarity of structure and function

Anatomy and physiology are inseparable because function always reflects structure. What a structure can do depends on its specific form.

Levels of structural organization

-chemical

-cellular

-tissue

-organ

-organ system

-organismal

Chemical Level

Simplest level of structural hierarchy. Atoms, tiny building blocks of matter, combine to form molecules. Molecules combine to form organelles, basic components of the microscopic cells.

Cellular Level

Cells are the smallest units of living things. All cells have some common functions, but individual cells vary widely in size and shape. Cells are made up of molecules.

Tissue Level

The simplest living creatures are single cells, but in complex organisms such as human beings, the hierarchy continues on to the tissue level. Tissues consist of similar types of cells.

Four basic tissue types

-epithelium (covers body surface and protects organs)

-muscle (provides movement)

-connective (supports and protects organs)

-nervous (provides rapid internal communication by transmitting electrical impulses)

Organ Level

Extremely complex functions become possible at this level. Organs are made up of different types of tissues. Ex: stomach produce digestive juices to churn and mix food.

Organ System Level

Organs work together to accomplish a common purpose. Ex: heart and blood vessels circulate blood to carry oxygen and nutrients to all body cells.

Organismal Level

Highest level of organization, represents the sum total of all structural levels working together to keep us alive.

necessary life functions

Maintain boundaries, movement, responsiveness, digestion, metabolism, dispose of wastes, reproduction, growth

maintain boundaries

internal environment remains distinct from the external environment

Movement

contractility (ability to move by shortening)

move body parts or substances though body

Responsiveness or excitability

The ability to sense changes (stimuli) in the environment and then respond to them.

Which system is most involved with responsiveness?

Because nerve cells are highly excitable and communicate rapidly with each other, the nervous system is most involved with responsiveness. All body cells are excitable to some extent.

Digestion

Breaking down of ingested food stuffs to simple molecules that can be absorbed into the blood.

Metabolism

Broad term includes all chemical reactions that occur within body cells.

excretion

Removal of wastes from metabolism and digestion

Ex: urea, carbon dioxide, feces

reproduction

Cellular division for growth or repair

Production of offspring

growth

Increase in size of a body part or of organism

hypertrophy

increase in cell size

hyperplasia

increase in number of cells

integumentary system

Protects the body as a whole from the external environment. Forms the external body covering, and protects deeper tissues from injury. Synthesizes vitamin D, and houses cutaneous (pain, pressure, etc) receptors and sweat and oil glands.

urinary system

Eliminates nitrogenous wastes and excess ions from the body. Regulates water, electrolyte and acid base balance of the blood.

cardiovascular system

Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs.

digestive system

Takes in nutrients, breaks them down, and eliminates unabsorbed matter (feces).

respiratory system

Takes in oxygen and eliminates carbon dioxide. The gaseous exchanges occur through the walls of the air sacs of the lungs.

nervous system

As the fast acting control system of the body, it responds to internal and external changes by activating appropriate muscles and glands.

endocrine system

Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.

skeletal system

Protects and supports body organs, and provides a framework the muscles use to cause movement. Blood cells are formed within bones. Bones store minerals.

muscular system

Allows manipulation of the environment,

locomotion, and facial expression.

Maintains posture, and produces heat.

lymphatic system

Picks up fluid leaked from blood vessels

and returns it to blood. Disposes

of debris in the lymphatic stream.

Houses white blood cells (lymphocytes)

involved in immunity. The immune

response mounts the attack against

foreign substances within the body.

reproductive system

Overall function is production of offspring. Testes produce sperm and male sex hormone, and male ducts and glands aid in delivery of sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones. The remaining female structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn.

survival needs

in appropriate amounts necessary for life - too little or too much is harmful

Nutrients

Oxygen

Water (appropriate hydrostatic pressure)

Normal body temperature

Appropriate atmospheric pressure

Nutrients

Taken in via the diet, contain the chemical substances used for energy and cell building.

Carbohydrates, proteins, fats, vitamins, minerals

Oxygen

Accounts for approx 20% of the air we breathe. Essential for ATP production

Water

Accounts for 60-80% of our body weight and is the single most abundant chemical substance in the body.

Normal body temperature

98.6° F

Atmospheric pressure

The force that air exerts on the surface of the body.

Homeostasis

Maintenance of relatively stable internal conditions despite continuous changes in environment. Aka dynamic state of equilibrium or balance.

What is essential to maintain homeostasis?

Communication within the body to monitor and regulate. All three components (receptor, control center, and effector) must be functional to maintain homeostasis.

Variable

Homeostasis control mechanism being regulated. Ex: body temperature, heart rate, blood pressure, oxygen content of blood, blood sugar, etc.

Receptor

First component: some type of sensor that monitors the environment and responds to changes called stimuli, by sending information (input) to the control center.

Control center

Second component: receives information (input) from the receptor along the afferent pathway. Determines the set point, which is the level or range at which a variable is to be maintained.

Effector

Third component: receives information (output) from the control center along the efferent pathway. Provides the means for the control centers response (output) to the stimulus.

Afferent pathway

Approaches the control center (monitors)

Efferent pathway

Exits the control center (issues orders to muscles or glands)

Negative feedback mechanisms

The output shuts off the original effect of the stimulus or reduces its intensity. Causes the variable to change in a direction opposite to that of the initial change, returning to its ideal value. If too fast, then slows. If hot, then cools.

Body temperature and blood sugar are regulated by what?

Negative feedback mechanism

some variables regulated by negative feedback mechanisms to maintain homeostasis

core body temperature, blood glucose, plasma calcium, amount of oxygen and carbon dioxide in blood, blood pressure, volume of body water

Main goal for negative feedback mechanisms?

To prevent sudden severe changes within the body.

Positive feedback mechanisms

The result or response enhances the original stimulus so that the response is accelerated. The change that results proceeds in the same direction as the initial change, causing the variable to deviate further and further from its original value or range.

Positive feedback mechanisms control...

Infrequent events that do not require continuous adjustments. Often referred to as cascades. Ex: labor contractions and blood clotting.

Homeostatic imbalance

Disturbance in homeostasis. Occurs when the usual negative feedback mechanisms are overwhelmed and destructive positive feedback mechanisms take over.

Anatomical position

Standard anatomical reference point, the body is erect with feet slightly apart. It resembles "standing at attention", except the palms face forward and the thumbs point away from the body.

Directional terms

Explains where one body structure is in relation to another.

superior (cranial)

toward the head end or upper part of a structure or the body; above

inferior (caudal)

away from the head end or toward the lower part of a structure or the body; below

anterior (ventral)

toward or at the front end of the body; in front of

posterior (dorsal)

toward or at the back end of the body; behind

medial

toward or at the midline of the body; on the inner side of

lateral

away from the midline of the body; on the outer side of

intermediate

between a more medial and a more lateral structure

proximal

closer to the origin of the body part or the point of attachment of a limb to the body trunk

distal

farther from the origin of a body part or the point of attachment of a limb to the body trunk

superficial (external)

toward or at the body surface