Unit 1: Levels of Organization
I.
II.
III.
IV.
V.
Introduction
a. The study of the human body probably began with our earliest ancestors
i. Mostly interested in injuries and illnesses
ii. Superstition and mysticism
1. Led to discoveries and observations
Anatomy and Physiology
a. Anatomy – the branch of science that deals with the structure (morphology) of body
parts; their forms and how they are organized
b. Physiology – concerns the functions of body parts; what they do and how they do it.
c. The topics of anatomy and physiology are difficult to separate because the stuctures of
body parts are so closely associated with their functions.
i. A particular body part’s function depends on the way the par is constructed—
that is, how its subparts are organized
ii. For example, the organization of the parts in the human hand with its long,
jointed fingers make it easy to grasp objects
1. The hollow chambers of the heart are adapted to pump blood through
tubular blood vessels
2. The shape of the mouth enables it to receive food
3. Teeth ar eshaped to break solid foods into small pieces
d. In 2003, researches completed deciphering the human genome—that is, the
biochemical instructions that run the human body
Levels of Organization
a. Basic Level of Organization
i. Atoms, molecules, macromolecules, cells, organelles, tissues, organs, organ
systems, organisms…and so on
b. Body parts can be described in terms of different levels of organization, such as atomic
differ in complexity level, molecular level, or the cellular level
i. Furthermore, body part from one level to the next.
Characteristics of Life
a. Before beginning a more detailed study of anatomy and physiology, it is helpful to
consider some of the trait s humans share with other organisms.
i. Metabolism – the sum total of all of the chemical reactions in the body that
break substances down and build them up
1. This includes: moving, eating, digesting, growing, making the sex, etc.
Maintenance of Life
a. Requirements of Organisms
i. Water
1. Most abundant chemical in the body
2. Required for many metabolic processes
3. Transports substances within the body
4. Regulates body temperature
ii. Foods
1. Provides the body with necessary chemicals (nutrients) in addition to
water
2. Chemicals are then used for energy (calories)
3. Provides raw materials for building new living matter
4. Regulates vital chem rxns
iii. Oxygen
1. Makes up about one-fifth of ordinary air
2. Used to release energy from food substances
3. Drives metabolic processes
iv. Heat
1. A form of energy!
2. Product of metabolic rxns
3. Determines the rate of rxns
4. TEMPERATURE IS A MEASURE OF THE DEGREE OF HEAT
v. Pressure
1. An application of force to something
a. Atmospheric pressure
i. Think about altitude sickness
b. Hydrostatic pressure
i. Think about swimming
ii. Heart action produces blood pressure
b. Although organisms require water, food, oxygen, heat, and pressure, these factors alone
are not enough to ensure survival.
i. Equilibrium
ii. Quality of resources
c. Health-care workers repeatedly monitor patients’ vital signs
i. These are observable body functions that reflect essential metabolic activities
ii. Assessment of vital signs includes measuring body temperature, blood pressure,
oxygen, and water.
iii. Absence of vital signs signifies death.
1. No spontaneous muscles and beating heart
2. No response to stimuli,
3. No reflexes
a. Pupillary reflexes
4. Brain waves cease
a. Flat electroencephalogram (EEG) signifies a lack of metabolic
activity in the brain
d. Homeostasis
i. Body parts function only when the concentrations of water, nutrients, and
oxygen and conditions of heat and pressure remain within certain narrow limits.
ii. The body maintains homeostasis through a number of self-regulating control
systems, or homeostatic mechanisms, that share the following components:
1. Receptors – provide information about specific conditions (stimuli) in
the internal environment
2. Set point – tells what a particular value should be (such as body
temperature at 37 degrees)
3. Effectors – cause responses that alter conditions in the internal
environment
iii. Homeostatic mechanisms work as follows:
1. Receptors measure deviations from the set point,
2. Effectors are activated that can return conditions toward normal
3. Conditions return toward normal, the deviation from the set point
progressively lessons, and the effectors are gradually shut down
a. This is called NEGATIVE FEEDBACK because the deviation from
the set point is corrected (moves in the opposite or negative
direction)
b. This latter aspect is important because it prevents a correction
from going too far
c. Examples: Furnace, caffeine, Xanax, tolerance
d. CHECK PG 6 – 7
e. Human Body Thermostat Example with Graphic
iv. Organization of the Human Body
1. Body Cavities
a. Axial – head, neck, and trunk
b. Appendicular – upper and lower limbs
c. Cranial cavity – le brain
d. Vertebral canal – spinal cord
e. Thoracic cavity – skin, skeletal (voluntary) muscles, and various
bones
f. Abdominopelvic cavity
g. Viscera
h. Diaphragm – broad, thin muscle that separates the thoracic
cavity from the lower abdominopelvic cavity
i. Mediastinum – separates the thoracic cavity into two
comaprtments, which contain the right and left lungs
i. The remaining thoracic viscera—heart, esophagus,
trachea, and thymus—are located within the
mediastinum
j.