1. Terminology & Homeostasis
Chapter 1
Terminology & Homeostasis
Anatomy & Physiology
ivyanatomy.com

2. Terminology Most anatomical terms have Greek or Latin origins Anatomy:
science of structures of the body (morphology)
Greek: ana = up, tome = cutting
Physiology:
science of functions of the organs
Greek: physis = nature, logy = the study of

3. Form follows Function Anatomical questions of the heart
The anatomy (form) of an organ should be based on its intended physiology (function)
Anatomical questions of the heart
How many chambers does the heart have?
Describe the location of the heart.
Physiological questions of the heart
How are electrical impulses generated within the heart?
How does the heart help maintain blood pressure?

4. Levels of Organization
All matter, including the human body, is composed of tiny particles called atoms.
subatomic particles
(protons, neutrons, electrons)
atom
molecule
organism
macromolecule
organ system
organelle
organ
tissue
cell

5. Levels of Organization
Subatomic Particles: electrons, protons, and neutrons
Atom: smallest unit of an element
(eg. hydrogen atom, lithium atom, etc.)
Molecule: particle of 2 or more atoms chemically joined together
(eg. water molecule, glucose molecule, etc.)
Macromolecule: A very large molecule
(eg. protein, DNA, etc.)
Organelle: Carries on specific activities within a cell
(eg. mitochondrion, Golgi apparatus, nucleus, etc.)
Continued…

6. Levels of Organization
Cell: the cell is the basic unit of life
Humans are composed of about 40 trillion cells
(muscle cell, nerve cell, etc.)
Tissue: group of similar cells that perform a specialized function
(epithelia, connective, muscle and nerve)
Organ: groups of different tissue
(skin, femur, heart, kidney, etc. )
Organ System: Group of organs that function together
(skeletal system, digestive system, etc.)
Organism: Homo sapiens (i.e. human)

7. Levels of Organization
Examples
subatomic particles
protons, neutrons, electrons
atom
oxygen atom, carbon atom
molecule
water molecule,
glucose molecule
macromolecule
DNA, proteins
organelle
mitochondrion,
Golgi apparatus, nucleus
cell
neuron, red blood cell, muscle cell
tissue
skeletal muscle tissue,
areolar connective tissue
organ
heart, liver, kidney, skin
organ system
cardiovascular system,
digestive system
organism
Homo sapiens (us!)
Atom
Table 1.1

8. Characteristics of Life
Complex
Organization
Organisms are composed of cells. Cells are composed precise arrangements of large molecules.
Responsiveness
detect changes in the environment
and react to those changes
Movement
ability to change positions or part of an organism
Growth and development
increase size and complexity

9. Characteristics of Life
Reproduction
forms new cells or new organisms
Digestion
breakdown food into simpler forms
Absorption
passage of substances through a membrane
Assimilation
converting absorbed molecules into different forms
Excretion
removing waste

10. Characteristics of Life
Process
Examples
Movement
Ability to change position of part of organism or entire organism
Digestion
Breakdown of food into smaller molecules that can be absorbed
Responsiveness
Ability to detect changes in the environment and respond to them
Absorption
Transport molecules through membranes
Growth
Increase size of body or organ
Circulation
Movement of substances in body fluids
Reproduction
DNA synthesis, Cell Division, Sexual Reproduction
Assimilation
Convert one molecule into a different molecule
Respiration
Converting energy from food into a form the cells can use
Excretion
Removal of waste products
Table 1.2

11. Requirements of an Organism
Water
transportation & metabolic processes
Food
growth and repair
Oxygen
required to release sufficient energy from food
Heat
controls the rate of chemical reactions
Pressure
required for breathing and circulation

12. Homeostasis
Homeostasis: the maintenance of a stable internal environment
Table 1.3 Examples of homeostatic mechanisms.
Examples of homeostatic mechanisms
Set-point value (average)
Normal Range
(estimations)
Body Temperature
37°C (98.6°F)
36.5 – 37.2°C
Blood Pressure
120/80 mmHg
100/70 –140/90 mmHg
Heart Rate
76 beats per minute
60 – 100 bpm
pH (whole blood)
7.4
7.35 – 7.45
Each mechanism maintains conditions near a set-point value. The conditions may fluctuate but they mostly remain within a normal range.

13. 3 Components of a Homeostatic Mechanism
Receptor : monitors the environment and provides information about changes in the conditions
Control Center: region in body that maintains the set-point value
Set-Point: target value that is maintained by the control center
(e.g. body temperature = 98.6°F or 37°C)
Effector: alters conditions in the environment (muscle or a gland)

14. Feedback Loops Negative Feedback Loop
returns conditions towards the set-point
maintains conditions within the normal range for homeostasis
“As conditions return towards normal, negative feedback gradually shuts down the effectors. This prevents a correction from going to far.”
Positive Feedback Loop
Drives conditions further away from the set-point
Causes the system to move away from equilibrium (runaway train)
Not involved in homeostasis

15. set-point control center Receptor effectors Stimulus Response
(muscles or glands)
Stimulus
Response
negative feedback
diminishes the stimulus

16. Brrrr! Example of Homeostasis and Negative Feedback Negative Feedback
Body temperature falls below set-point (37°C)
Thermoreceptors transmit impulse to hypothalamus
Negative
Feedback
Brrrr!
Body temperature returns towards the set-point.
Hypothalamus detects the body temp is falling below normal range
skeletal muscles start shivering, producing heat.

17. Positive feedback cycle
child birth
Stretch receptors signal the hypothalamus
Hypothalamus activates pituitary gland
Baby stretches the cervix
Pituitary gland releases Oxytocin
Uterus contracts, pushing the head of baby against the cervix
Openstax college
Oxytocin is carried through the blood to the uterus
Oxytocin triggers uterine contractions

18. Positive Feedback & Childbirth
Positive feedback continues to increase the strength of contractions. The cycle ends only after the baby is born and the cervix is no longer stretched.

19. Attribution
NIH image of human brain:
Childbirth. Openstax College:
Mitochondrion. . "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI: /wjm/ ISSN (Own work) [CC BY 3.0 ( via Wikimedia Commons
Animal Cell. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI: /wjm/ ISSN (Own work) [CC BY 3.0 ( via Wikimedia Commons
Heart. By Patrick J. Lynch, medical illustrator (Patrick J. Lynch, medical illustrator) [CC BY 2.5 ( via Wikimedia Commons
Cardiovascular System. By Bryan Brandenburg ( [CC BY-SA 3.0 ( via Wikimedia Commons
David Wiley Photo. Mark A. Philbrick / CC BY