Introduction to Physiology
Slide One – physiological systems from a human perspective
•Nervous and endocrine systems are control systems of the body
•Nervous System
oThe brain (central nervous system) receives information from various
regions of the body through peripheral nerves which will then be sent
out through either motor control signals to muscles or via somatic
nerves to various organs and glands
•Endocrine System
oSimilarly it is a control / regulatory system
oThere are a number of endocrine glands throughout the body which
produce and secrete hormones circulated in the blood that have an
influence on organ structures
•These two systems can be known as the command and control regulatory
systems
Slide Two – physiological systems from a non-human perspective
•The functions of the nervous and endocrine system are very similar as we look
at other animals
•There can also be a number of differences
oThe organization of neurons can be different from what we see in
humans
•Looking at individual nerves, the function in animals are similar to what we see
in humans and other animals
Slide Three – physiological systems from a human perspective
•Muscular / Skeletal / Integumentary Systems serve the purposes of movement /
support / binding us together / defence
oIntegumentary system is the human skin system\
oFirst line of defence to keep things out
•We use muscles to move, there are various types of muscles
•Skeletal muscles are used to move around
oSmooth muscles help for example to propel food in the gut
Slide Four – physiological systems from a non-human perspective
•Other than the size and shape of the head, many skeletal systems are similar
•A bird skeleton differs from the human skeleton because birds have hollow
bones which make them lighter for flight
•Cartilaginous fish have skeletal systems made up of cartilage instead of bones
•Muscle function in birds are similar to humans and animals
•Hummingbirds are on crack beating their wings at more than 100 times /
second
oThe mechanisms for muscle contractions in hummingbirds are
significantly different than in human or other animal systems
•Invertebrates have their skeleton on the outside called the exoskeleton
•Fish are cold blooded, they adapt their body temperature to that of the
environment
oNot always so:
Tuna
Sharks
Marlin
oHave the ability to raise their internal temperature of their muscles and
keep it 50-100 degrees higher than the rest of their body and the
environment
oCore of muscles generate heat and trap heat
Slide Five – human perspective
•Respiratory system’s job is to obtain oxygen and to excrete carbon dioxide
•Circulatory system delivers oxygen to the body and takes metabolic carbon
dioxide to the lungs where its excreted
•Cardio-respiratory functions are intimately linked
•Any fluid that leaks out of the circulatory system is drained back into the
circulatory system through the lymph
Slide Six – non-human perspective
•Looking at cardiovascular and respiratory systems between humans and
animals you see a number of differences appearing
oFish breathe using gills with the exception of fish that breathe air
compared to water
-e.g. lungfish
•Human lungs are sub-divided into tiny compartments called alveoli
oThere are so many subdivisions (millions and millions) that if you took a
cross section of a human lung, it would appear solid
oCompared to a frog lung which is essentially just a bag with air with a
few ridges on the inner surface
There are no subdivisions into smaller compartments in an
amphibian lung
•Reptilian lungs are a little more complex than amphibian lungs
oYou see division of the lungs into a few chambers
oNowhere near as subdivided as the human / mammalian lung
oIt was thought that reptiles couldn’t run and breathe at the same time
The same muscles used to breathe (inflate their lungs) are are
used to run
This is true to a certain extent (they are limited in their ability to
run) but they can breathe to some degree
•The bird lung looks nothing like the amphibian / reptilian / mammalian lung
oNot an intermediate
oResembles a dinosaur lung
•Human heart is completely divided into left and right side with four chambers
•Fish hearts are also four chambered, but they are arranged in series rather
than in a parallel arrangement in comparison to a human heart
•Amphibian heart looks like a human heart, but it has two atria and only one
ventricle