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Chapter 1
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anatomy - science of structures (morphology)
ana = up, tome = cutting
physiology - science of functions
physis = nature, logy = the study of
Form follows Function
The anatomy (form) of an organ should be based on its
intended physiology (function)
Anatomy (form) questions of the heart
• How many chambers does the heart have?
• Describe the location of the heart.
• Identify the tissues within the wall of the heart.
Physiology (function) questions of the heart
• Describe how electrical currents are conducted through the heart.
• Describe how the heart helps maintain blood pressure.
Levels of Organization
subatomic particles
(protons, neutrons, electrons)
atom
(hydrogen, carbon, oxygen)
molecule
organism
(water, glucose)
(Homo sapien)
organ system
macromolecule
(cardiovascular, digestive)
(proteins, DNA, RNA)
organ
(heart, liver, stomach)
organelle
(mitochondrion, nucleus)
tissue
cell
(basic unit of life)
(nervous, cardiac muscle)
Levels of Organization
Level
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
Table 1.1
Atom
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!)
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
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
Characteristics of Life
Process
Examples
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
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
Homeostasis
Homeostasis – is the maintenance of a stable
internal environment
Table. Examples of homeostatic mechanisms. Each mechanism
maintains conditions near a set-point value. The conditions may
fluctuate but they mostly remain within a normal range.
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
Components of a Homeostatic Mechanism
Receptor
• monitors the environment and provides
information about changes in the conditions
Control Center
• region in body that sets the normal range
• Set-Point: target value that is maintained by the control center
(e.g. body temperature = 37°C)
Effector
• alters conditions in the environment (muscle or a gland)
Feedback Loops
1. 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.”
2. 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
control center
set-point
Receptor
effectors
(muscles or glands)
Stimulus
Response
negative feedback
diminishes the stimulus
Example of Homeostasis and Negative Feedback
Body temperature
falls below set-point
(37°C)
Negative
Feedback
Brrrr!
Thermoreceptors
transmit impulse to
hypothalamus
Body temperature returns
towards the set-point.
Hypothalamus
detects the body
temp is falling
below normal range
skeletal muscles start
shivering, producing heat.
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 triggers uterine
contractions
Oxytocin is carried through
the blood to the uterus
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.
Attribution
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NIH image of human brain: http://upload.wikimedia.org/wikipedia/commons/0/0a/Human_brain_NIH.png
Childbirth. Openstax College: http://cnx.org/contents/[email protected]:7/Anatomy_&_Physiology#figch01_05_02
NIH image of human brain: http://upload.wikimedia.org/wikipedia/commons/0/0a/Human_brain_NIH.png
Mitochondrion. . "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. (Own work)
[CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
http://upload.wikimedia.org/wikipedia/commons/f/f2/Blausen_0644_Mitochondria.png
Animal Cell. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. (Own work) [CC
BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
http://upload.wikimedia.org/wikipedia/commons/4/4e/Blausen_0208_CellAnatomy.png
Heart. By Patrick J. Lynch, medical illustrator (Patrick J. Lynch, medical illustrator) [CC BY 2.5
(http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons
http://upload.wikimedia.org/wikipedia/commons/4/4f/Heart_anterior_large.jpg
Cardiovascular System. By Bryan Brandenburg (http://bryanbrandenburg.net/wikpedia-heart-3d//) [CC BY-SA 3.0
(http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
http://upload.wikimedia.org/wikipedia/commons/c/cb/Human_Heart_and_Circulatory_System.png
David Wiley Photo. Mark A. Philbrick / CC BY http://farm8.staticflickr.com/7264/7754795758_fc7af56605.jpg