ANIMAL: BASIC FORM AND FUNCTION
Animals vary in form and function. An organism has a distinct body plan that limits its size and shape.
Animals’ bodies are also designed to interact with their environments.
BODY PLANS
Asymmetrical animals - animals with no pattern or symmetry.
Radial symmetry - when an animal has an up-and-down orientation.
Bilateral symmetry - a plane cut from front to back separates the animal into definite right and left
sides.
EPITHELIAL TISSUES - cover the outside of organs and structures in the body and line the lumens of
organs in a single layer or multiple layers of cells.
1. SQUAMOUS EPITHELIAL CELLS - generally round, flat, and have a small, centrally located
nucleus. They facilitate diffusion in tissues, such as the areas of gas exchange in the lungs and the exchange
of nutrients and waste at blood capillaries.
2. CUBOIDAL EPITHELIAL CELLS - are cube-shaped with a single, central nucleus. They prepare and
secrete glandular material. They are also found in the walls of tubules and in the ducts of the kidney and
liver.
3. COLUMNAR EPITHELIAL CELLS - are taller than they are wide. These cells absorb material from
the lumen of the digestive tract and prepare it for entry into the body through the circulatory and lymphatic
systems.
Animals vary in form and function. An organism has a distinct body plan that limits its size and shape.
Animals’ bodies are also designed to interact with their environments.
BODY PLANS
Asymmetrical animals - animals with no pattern or symmetry.
Radial symmetry - when an animal has an up-and-down orientation.
Bilateral symmetry - a plane cut from front to back separates the animal into definite right and left
sides.
EPITHELIAL TISSUES - cover the outside of organs and structures in the body and line the lumens of
organs in a single layer or multiple layers of cells.
1. SQUAMOUS EPITHELIAL CELLS - generally round, flat, and have a small, centrally located
nucleus. They facilitate diffusion in tissues, such as the areas of gas exchange in the lungs and the exchange
of nutrients and waste at blood capillaries.
2. CUBOIDAL EPITHELIAL CELLS - are cube-shaped with a single, central nucleus. They prepare and
secrete glandular material. They are also found in the walls of tubules and in the ducts of the kidney and
liver.
3. COLUMNAR EPITHELIAL CELLS - are taller than they are wide. These cells absorb material from
the lumen of the digestive tract and prepare it for entry into the body through the circulatory and lymphatic
systems.
