Physiology
Muscular System – Microscopic Anatomy
**Write all of your work in your spiral notebook.
Background
The human body is composed, microscopically, of four basic tissue types – epithelial, connective,
muscle and nervous. We will eventually look at epithelial and connective tissues in the context of
the integumentary and skeletal systems. Today we are going to look at muscle tissue in the context of
the muscular system, the cardiovascular system and the digestive system.
Muscle tissue makes up approximately 50% of the body’s mass. These tissues are specialized for
contraction – the ability to shorten and then return to their original shape and size. There are three
subtypes of muscle tissue – skeletal, smooth and cardiac. Each varies slightly in structure and in
their location, while always performing the basic function of contraction. These contractions will
always produce movement – of bones-skeletal, of food and other body fluids-smooth and of bloodcardiac. The contractions of muscle tissue are also the major source of our internal body heat as we
saw through our study of thermoregulation and homeostasis.
Focus Questions
Think about the following questions as you do the lab.
• What are the types of muscle tissue and how can they be identified microscopically?
• What is the relationship between structure and function in the different types of muscle tissue?
Procedure
A. Pre-lab Preparation
1. What do you already know about muscles and their functions?
2. Predict how skeletal, cardiac and smooth muscle tissue will differ? Why did you make the
predictions you did?
2. What role does skeletal, cardiac and smooth muscle tissue play in homeostasis in the body?
B. Microscope Use and Review
1. You will be using the compound microscope today. There is an eyepiece and three objectives. The
three objectives have the following magnification ratings: 4X, 10X, and 40X. The eyepiece has a
magnification rating of 10X. The total magnification viewed at any given time is a product of the
eyepiece magnification times the objective magnification.
2. Always begin any viewing session with the 4X objective in place
a. Use the course adjustment knob to bring the object into focus.
b. Center the object in the field of view (the entire area visible at any given magnification).
c. Continue to focus by using the fine focus knob.
d. To view at a higher magnification, rotate to the 10X or 40 X objective, once using the 40 X
objective ONLY use the fine focus knob.
C. Microscopic Drawing.
1. The following rules should be followed for all drawings using the microscope.
a. Use a sharp-pointed pencil only, not ink or colored pencil.
b. Drawings are to be "hard-line", not sketches, and should be as accurate and detailed as
possible – neatness counts.
c. Draw only what you see, not what you think you should see.
d. The drawing should be accurately to scale – that is, it should have the same proportions in
your drawing that it does under the microscope.
e. Label lines are done darkly, using a ruler. Do not cross label lines.
f. Labels are lined up, neatly, along the line drawn on the right side.
D. Observing Muscle Tissue
1. Obtain three prepared slides of – skeletal, smooth and cardiac muscle. Conduct a microscopic
observation of all three at 40X. This will magnify the tissue 400 times the original size. Draw your field
of view for each tissue type in a data section in your spiral notebook. ***Indicate the magnification of
your drawings along with the title. Use the diagram below as a guideline for your three drawings.
Title of Drawing: Smooth Muscle Tissue
Magnification of Drawing: __________
2. Make a detailed microscopic drawing of smooth muscle tissue. Identify the power you observed
the tissue at. ***Label as many of the following structures as possible: muscle cell; nucleus; cell
membrane (plasmalemma).
3. Make a detailed microscopic drawing of cardiac muscle tissue. Identify the power you observed
the tissue at. ***Label as many of the following structures as possible: muscle cell; nucleus; cell
membrane (sarcolemma); striations, intercalated disk.
4. Make a detailed microscopic drawing of skeletal muscle tissue – cross section. ***Label as many
of the following structures as possible: muscle fiber; nucleus; cell membrane (sarcolemma);
sarcoplasm (cytoplasm)
E. Comparing Muscle Tissue
1. Copy the table below into your notebook and complete the table based on your observations and
research.
Skeletal Muscle
Smooth Muscle
Cardiac Muscle
Shape
# of nuclei
Location of nuclei
Presence of
striations
Location in Body
Voluntary/involuntary
Analysis Questions
1. What is the purpose/role of the striations in the skeletal muscle tissue?
2. Why do you think skeletal muscle has multi-nucleated cells?
3. In addition to the blood vessels and the digestive system, identify (2) locations for smooth muscle
in the human body. What is the purpose/role of the smooth muscle in those locations?
4. What makes cardiac tissue unique from the other two types of muscle tissue?
Write a summary of what you learned from this lab activity.