The three types of muscle cells are skeletal, cardiac, and smooth. Their morphologies match their specific functions in the body. Skeletal muscle is voluntary and responds to conscious stimuli. The cells are striated and multinucleated appearing as long, unbranched cylinders. Cardiac muscle is involuntary and found only in the heart. Each cell is striated with a single nucleus and they attach to one another to form long fibers. Cells are attached to one another at intercalated disks. The cells are interconnected physically and electrochemically to act as a syncytium. Cardiac muscle cells contract autonomously and involuntarily. Smooth muscle is involuntary. Each cell is a spindle-shaped fiber and contains a single nucleus. No striations are evident because the actin and myosin filaments do not align in the cytoplasm.
Muscle cells contain two proteins, actin and myosin. Their interaction contracts their length, causing movement. 3 types of muscle tissue:
Skeletal or Striated muscle cells are long, cylindrical, multinucleated, and striated due to intercalated disks. They are voluntary and pull on bone, causing movement.
Smooth or nonstriated muscle cells are long, unicellular and spindle-shaped; involuntary and found in digestive tract, arteries and veins, and the ureters of the kidney. Arranged in two layers around hollow organs:
outer longitudinal layer
inner circular one.
Cardiac muscle are cylindrical, striated, uninucleated, and branched, connecting to other cardiac cells via intercalated disks. Contract autonomously and involuntarily. Responsible for pumping blood through the heart.
cardiac muscle
heart muscle, under involuntary control, composed of striated cells that attach to form fibers, each cell contains a single nucleus, contracts autonomously
myocyte
muscle cells
skeletal muscle
usually attached to bone, under voluntary control, each cell is a fiber that is multinucleated and striated
smooth muscle
under involuntary control, moves internal organs, cells contain a single nucleus, are spindle-shaped, and do not appear striated; each cell is a fiber
striation
alignment of parallel actin and myosin filaments which form a banded pattern
Watch this video to learn more about muscle tissue. In looking through a microscope how could you distinguish skeletal muscle tissue from smooth muscle?
Skeletal muscle cells are striated.
1. Striations, cylindrical cells, and multiple nuclei are observed in ________.
A) skeletal muscle only
B) cardiac muscle only
C) smooth muscle only
D) skeletal and cardiac muscles
A
2. The cells of muscles, myocytes, develop from ________.
A) myoblasts
B) endoderm
C) fibrocytes
D) chondrocytes
A
3. Skeletal muscle is composed of very hard working cells. Which organelles do you expect to find in abundance in skeletal muscle cell?
A) nuclei
B) striations
C) golgi bodies
D) mitochondria
D
1. You are watching cells in a dish spontaneously contract. They are all contracting at different rates; some fast, some slow. After a while, several cells link up and they begin contracting in synchrony. Discuss what is going on and what type of cells you are looking at.
The cells in the dish are cardiomyocytes, cardiac muscle cells. They have an intrinsic ability to contract. When they link up, they form intercalating discs that allow the cells to communicate with each other and begin contracting in synchrony.
2. Why does skeletal muscle look striated?
Under the light microscope, cells appear striated due to the arrangement of the contractile proteins actin and myosin.