SBI3C: Animal Cell Hierarchy and Homeostasis

Hierarchy of Structures in Animals

• Multi-cellular organisms are made up of specialized cells that have a particular structure and perform a specific function.
• Cells combine to form tissues, which are a collection of similar cells that perform a specific function.
• When two or more types of tissues work together, they form an organ.
• Organs and structures work together to perform a major vital body function, forming an organ system.
• Organ systems working together create an organism.

Tissues

• There are four types of tissues: nerve, muscle, epithelial, and connective.
• Each type of tissue has a specific function and is composed of specialized cells.

Epithelial Tissue

• Epithelial tissue is a group of tightly packed cells that cover the body's surfaces, line organs, and cavities.
• Examples of epithelial tissue include skin and the lining of organs.
• Epithelial tissue can be a single cell layer or multiple layers.

Epithelial Tissue Functions

• Allows materials to pass through the body (e.g., oxygen in the lungs).
• Protects the body from injury.
• Provides support to the body.

Connective Tissue

• Connective tissue is made up of both specialized cells and non-living substances.
• Examples of connective tissue include blood, bone, cartilage, and tendons.
• Connective tissue provides support, protection, and connections between organs.

Connective Tissue Functions

• Supports and connects the body's organs.
• Transports nutrients and wastes throughout the body (e.g., blood).

Bone

• Bone is made of living bone cells surrounded by a hard, non-living material.
• Bones are connected to each other by ligaments and muscles are attached to bones by tendons.
• Cartilage is found in joints.

Nerve Tissue

• Nerve tissue is the most complex tissue and makes up the brain, spinal cord, and nerves.
• Nerve tissue transmits signals throughout the body.

Nerve Tissue Functions and Cell Types

• Transmits signals through the body.
• Consists of three main types of nerve cells: sensory neurons, motor neurons, and interneurons.
• Sensory neurons carry information from the body to the brain.
• Motor neurons carry information from the brain to the body.
• Interneurons connect sensory and motor neurons.

Muscle Tissue

• Muscle tissue is made up of cells that can contract (get shorter).
• There are three types of muscle cells: skeletal, cardiac, and smooth.
• Skeletal muscles are voluntary (controlled by the individual).
• Cardiac muscles are involuntary (controlled by the heart).
• Smooth muscles are involuntary (controlled by organs and other tissues).

Muscle Tissue Functions

• Connects bones, allowing us to move.
• Enables organs to function properly (e.g., heart pumping blood).
• Breaks down food in the stomach and intestines.

Organ Systems

• There are eight organ systems in the human body: nervous, respiratory, reproductive, musculoskeletal, circulatory, digestive, excretory, and endocrine.
• Each organ system is composed of groups of organs that work together to perform a specific function.

Homeostasis

• Homeostasis is the body's ability to maintain a healthy balance.
• Normal levels of bodily functions include:
  • Blood pH: 7.35
  • Temperature: 37°C
  • Heart Rate: 72 beats per minute

Diagnosis

• When sick, doctors compare individual values to normal levels to diagnose and treat illnesses.