The Human Body:

1
Chapter 1

• The Human Body
• An Orientation
• Part A

2
Overview of Anatomy and Physiology

• Anatomy The study of structure of the body
• Subdivisions
• Gross or macroscopic (e.g., regional, surface,
  and systemic anatomy)
• Microscopic (e.g., cytology and histology)
• Developmental (e.g., embryology)

3
Overview of Anatomy and Physiology

• Essential tools for the study of anatomy
• Anatomical terminology
• Observation
• Palpation
• Auscultation

4
Overview of Anatomy and Physiology

• Physiology The study of function of the body at
  many levels
• Subdivisions are based on organ systems (e.g.,
  renal, digestive, cardiovascular physiology)

5
Overview of Anatomy and Physiology

• Essential tools for the study of physiology
• Ability to focus at many levels (from systemic to
  cellular and molecular)
• Basic physical principles (e.g., electrical
  currents, pressure, and movement)
• Basic chemical principles

6
Principle of Complementarity

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

7
Levels of Structural Organization

• Chemical atoms and molecules (Chapter 2)
• Cellular cells and their organelles (Chapter 3)
• Tissue groups of similar cells (Chapter 4)
• Organ contains two or more types of tissues
• Organ system organs that work closely together
• Organismal all organ systems

8
Organelle
Molecule
Atoms
Smooth muscle cell
Cellular levelCells are made up ofmolecules.
2
Chemical levelAtoms combine to form
molecules.
1
Smooth muscle tissue
Cardiovascularsystem
Tissue levelTissues consist of similartypes
of cells.
3
Heart
Bloodvessels
Blood vessel (organ)
Smooth muscle tissue
Connective tissue
Epithelialtissue
Organ levelOrgans are made up of different
typesof tissues.
4
Organ system levelOrgan systems consist of
differentorgans that work together closely.
Organismal levelThe human organism is made
upof many organ systems.
5
6
Figure 1.1, step 6
9
Overview of Organ Systems

• Major organs and functions of the 11 organ
  systems

10

• Digestive system
• Nervous system
• Respiratory system
• Cardiovascular system
• Lymphatic system
• Urinary system Organ Systems
• Muscular system
• Skeletal system
• Integumentary system
• Endocrine system
• Reproductive system

11
Organ Systems Interrelationships

• All cells depend on organ systems to meet their
  survival needs
• Organ systems work cooperatively to perform
  necessary life functions

12
Necessary Life Functions

• Boundary Maintaining boundaries between
  internal and external environments
• Plasma membranes
• Skin
• Movement (contractility)
• Of body parts (skeletal muscle)
• Of substances (cardiac and smooth muscle)

13
Necessary Life Functions

• Responsiveness The ability to sense and respond
  to stimuli
• Withdrawal reflex
• Control of breathing rate
• Digestion
• Breakdown of ingested foodstuffs
• Absorption of simple molecules into blood

14
Necessary Life Functions

• Metabolism All chemical reactions that occur in
  body cells
• Catabolism and anabolism
• Excretion The removal of wastes from metabolism
  and digestion
• Urea, carbon dioxide, feces

15
Necessary Life Functions

• Reproduction
• Cellular division for growth or repair
• Production of offspring
• Growth Increase in size of a body part or of
  organism

16
Survival Needs

• Nutrients
• Chemicals for energy and cell building
• Carbohydrates, fats, proteins, minerals, vitamins
• Oxygen
• Essential for energy release (ATP production)

17
Survival Needs

• Water
• Most abundant chemical in the body
• Site of chemical reactions
• Body temperature
• Affects rate of chemical reactions
• Atmospheric pressure
• For adequate breathing and gas exchange in the
  lungs

18
Homeostasis

• It is the maintenance of a relatively stable
  internal environment despite continuous changes
  both inside and out
• A dynamic state of equilibrium

19
Homeostatic Control Mechanisms

• Involve continuous monitoring and regulation of
  many factors (variables)
• Nervous and endocrine systems accomplish the
  communication via nerve impulses and hormones

20
Components of a Control Mechanism

• Receptor (sensor)
• Monitors the environment
• Responds to stimuli (changes in controlled
  variables)
• Control center
• Determines the set point at which the variable is
  maintained
• Receives input from receptor
• Determines appropriate response

21
Components of a Control Mechanism

• Effector
• Receives output from control center
• Provides the means to respond
• Response acts to reduce or enhance the stimulus
  (feedback)

22
4
OutputInformation sent alongefferent
pathway toeffector.
3
Input Informationsent along
afferentpathway to controlcenter.
ControlCenter
Afferentpathway
Efferentpathway

2
Receptor
Effector
5

Receptordetectschange.
Responseof effectorfeeds backto reducethe
effect ofstimulusand returnsvariable
tohomeostaticlevel.

1
IMBALANCE
Stimulusproduceschange invariable.
BALANCE
IMBALANCE
Figure 1.4, step 5
23
Negative Feedback

• The response reduces or shuts off the original
  stimulus
• Examples
• Regulation of body temperature (a nervous
  mechanism)
• Regulation of blood volume by ADH (an endocrine
  mechanism)

24
Control Center (thermoregulatory center in brain)
Information sent along the afferent pathway to
control center
Information sent along the efferent pathway
to effectors
Afferent pathway
Efferent pathway
Receptors Temperature-sensitive cells in skin and
brain
Effectors Sweat glands
Sweat glands activated
Response Evaporation of sweat Body temperature
falls stimulus ends
Stimulus Body temperature rises
BALANCE
Stimulus Body temperature falls
Response Body temperature rises stimulus ends
Receptors Temperature-sensitive cells in skin and
brain
Effectors Skeletal muscles
Afferent pathway
Efferent pathway
Shivering begins
Information sent along the afferent pathway to
control center
Information sent along the efferent pathway to
effectors
Control Center (thermoregulatory center in brain)
Figure 1.5
25
Negative Feedback Regulation of Blood Volume by
ADH

• Receptors sense decreased blood volume
• Control center in hypothalamus stimulates
  pituitary gland to release antidiuretic hormone
  (ADH)
• ADH causes the kidneys (effectors) to return more
  water to the blood

26
Positive Feedback

• The response enhances or exaggerates the original
  stimulus
• Enhancement of labor contractions by oxytocin
  (Chapter 28)
• Platelet plug formation and blood clotting

27
1
Break or tearoccurs in bloodvessel wall.
Positive feedbackcycle is initiated.
2
3
Releasedchemicalsattract moreplatelets.
Plateletsadhere to siteand
releasechemicals.
Positivefeedbackloop
Feedback cycle endswhen plug is formed.
4
Platelet plugforms.
Figure 1.6, step 4
28
Homeostatic Imbalance

• Disturbance of homeostasis
• Increases risk of disease
• Contributes to changes associated with aging
• May allow destructive positive feedback
  mechanisms to take over (e.g., heart failure)