Animal OrgansSNC2P Biology

The Hierarchy of StructureLevel 5 Organism (many different organ systems working together

Level 4 System (one or more organs that work together to perform a body function)

Level 3 Organ (structure made of two or more types of tissue that work together to do a specific task)

Level 2 Tissue (group of similar cells that perform the same function)

Level 1 Cell (the most basic unit of living things)

OrgansSimilar to cells that work together to form tissues, a group of tissues that work together to perform a complex task are known as organs.

Organ

● Different tissues working together to perform a complex task

Animal OrgansThe Terminologia Anatomica (TA) states that there are over 7500 different named parts in the human body, many of which are organs.

Among them we have:

● Skin● Lungs● Heart● Stomach● Intestines

Are you able to think of any others?

Animal Organs - The Skin● The skin is the largest organ in your body and is your first line of defense

from external factors

● It is made up of two different layers; the epidermis and the dermis

○ Epidermis: The outer protective layer of the skin. Made up of epithelial tissue.

○ Dermis: The inner layer of the skin. Made up of connective tissue, nerve tissue, and muscle tissue.

Animal Organs - The LungsThe lungs are a pair of organs that are involved in respiration. Your lungs allow you to breathe in oxygen and breathe out carbon dioxide. The lungs are made of connective tissue and epithelial tissue.

When you breathe, air passes through the pharynx, the trachea, the bronchus, and smaller bronchial tubes into tiny air sacs, called alveoli. These alveoli are surrounded by thin wall blood vessels called capillaries. Oxygen travels from the alveoli through the capillaries into the blood.

Animal Organs - The HeartThe heart is a muscular pump that supplies blood to all parts of the body.

● An adult human heart is weighs about 300g

● In an average lifetime, the heart beats about 3.5 billion times

The heart is divided into four chambers: the left and right atria, and the left and right ventricles.

Animal Organs - The StomachWhen you eat, various organs assist with the digestive process. One of these organs is the stomach.

● The stomach is made of epithelial, connective, nervous, and muscle tissues.

● An adult human stomach can hold around 1.5 liters (nearly half a gallon) of food/drink.

● Food doesn’t break down completely in the stomach. In fact, most of digestion happens in the small intestines.

Animal Organs - IntestinesThe intestines are an area of chemical digestion and removal of wastes. There are two intestines in the human body: the large intestine and the small intestine.

● Despite its name, the small intestine (30m2) has much more surface area than the large intestine (2m2). What does this tell you about the nutrient absorption of each intestine?

Humans vs. Other AnimalsAll animals have organs to perform complex tasks. However, some animals have their organs arranged differently, lack certain organs, or have several of the same organ.

Humans vs. Other Animals● For example, a frog’s heart has three chambers, while a human’s heart has

four.

Humans vs. Other Animals● Worms have five hearts while humans only have one

Humans vs. Other Animals● A cow has four stomachs, while a human has only one.

Humans vs. Other Animals● Fish have gills instead of lungs, which allow them to breathe underwater

Recap● Similar to cells that work together to form tissues, a group of tissues that

work together to perform a complex task are known as organs.

● Animal organs include the skin, stomach, lungs, and heart among many others.

● All animals have organs to perform complex tasks. However, some animals have their organs arranged differently, lack certain organs, or have several of the same organ.