Types of Animal Cells

Types of Animal Cells

• The cell is the basic unit of life, and there are hundreds of different types of cells in the body.

Stem Cells

• Stem cells can differentiate into other types of cells and can also divide in self-renewal to produce more of the same type of stem cells.

Red Blood Cells (Erythrocytes)

• Shaped like a biconcave disc (donut-shaped)
• Fairly flexible, allowing them to squeeze through thin blood capillaries
• Lack a nucleus and cytoplasmic organelles
• Uniform in size, can be used as a size reference for other cell types
• Stain pink with eosin
• Main roles: transport oxygen, help control pH, and release carbonic anhydrase

Frog Red Blood Cells

• Oval shape with a nucleus inside each RBC

White Blood Cells (Leukocytes)

• Vital component of the immune system
• Larger than RBCs
• Nucleated with spherical or kidney-shaped or lobed nucleus
• Five different types: granulocytes (Neutrophils, Eosinophils, and Basophils) and agranulocytes (Lymphocytes and Monocytes)

Platelets

• Fragments of megakaryocytes produced in the bone marrow
• Have surface proteins that allow them to bind to one another and to damaged blood vessel walls
• Recruit when bleeding occurs, initiating hemostasis and forming a blood clot with fibrin

Epithelial Cells

• Specialized to stick tightly to one another
• Line the interior of hollow organs or cover surfaces like the skin
• Three shapes: flat (squamous), cube-shaped (cuboidal), and tall (columnar)
• Can be one cell layer thick (simple epithelium) or many layers thick (stratified epithelium)

Nerve Cells (Neurons)

• Transmit information throughout the body in the form of electrical signals or nerve impulses
• Structurally, have four specific regions: cell body, dendrites, axon, and axon terminals

Neuroglial Cells (Glia)

• Cells of the nervous system that are not involved in the conduction of nervous impulses
• Very common in the brain

Muscle Cells

• Three types: skeletal, cardiac, and smooth muscle
• Skeletal and cardiac muscle cells are striated due to the aligned arrangement of myosin and actin proteins
• Muscle tissue is responsible for movement of the body

Fat Cells (Adipocytes)

• Specialized to store energy in the form of adipose tissue or fat
• Vacuolar cells with a lipid droplet and cytoplasm
• Nucleus is flat and at the edge of the cell
• White fat cells vary in size, but average 0.1 mm in diameter
• Fat inside white fat cells is mainly made up of triglycerides and cholesterol ester, stored in semi-liquid form

Sex Cells (Gametes)

• Reproductive cells produced in male and female gonads
• Male sex cells (sperm) are motile with a flagellum
• Female sex cells (ova) are non-motile and relatively large in comparison
• Unite during fertilization to form a new individual
• Reproduce by meiosis, while other body cells replicate by mitosis