Human Body Tissues and Systems

Learning Objectives

• Learning objectives discuss tissue types and their functions.
• Learning objectives discuss body systems and their functions.
• The final learning objective is to define homeostasis.

What is Tissue?

• Tissue consists of specialized cells performing a shared bodily function.

Four Types of Tissues in the Human Body

• Epithelial tissue lines body surfaces and cavities.
• Connective tissue supports and bonds body parts.
• Muscular tissue facilitates body and part movement.
• Nervous tissue receives stimuli and conducts impulses.

Function of Epithelial Tissue

• Epithelial tissue comprises tightly packed cells forming a sheet.
• Epithelial tissue protects underlying structures.
• Epithelial tissue functions include secretion (glands), absorption, excretion, and filtration.

Connective Tissue

• Connective tissue binds organs together.
• Connective tissue provides support and protection.
• Connective tissue fills spaces.
• Connective tissue produces blood cells.
• Connective tissue stores fat, fluid, and nutrients.
• Connective tissue is the most common tissue, found throughout the body.

Muscle Tissue

• Muscle tissue facilitates movement within the body.
• Muscle cells are called muscle fibers.
• Muscle fibers can be striated or non-striated.

Types of Muscle Tissue

• Skeletal Muscle: Cells are striated and voluntary.
• Cardiac Muscle: Cells are striated and involuntary.
• Smooth Muscle: Cells are non-striated and involuntary.

Nervous Tissue

• Nervous tissue comprises neurons(nerve cells).
• Nervous tissue neurons conduct impulses/information: sensory input, integration, and motor output.
• Nervous tissue neuron structure includes dendrites, cell body, and axon.
• Nervous tissue includes neuroglia (support cells).
• Neuroglia supports and nourishes neurons.
• Nervous tissue serves as a messenger system within the body.

Organs

• Organs consist of two or more tissue types.
• Organs organize to accomplish tasks that individual tissues cannot.

Body Systems

• Body systems comprise organs and other structures working together.
• Body systems collectively achieve more than a single organ could independently.

Skeletal System

• The skeletal system supports and protects the body.
• The skeletal system stores minerals.
• The skeletal system is a site of blood cell production.

Muscular System

• The muscular system provides skeletal movement.
• The muscular system produces heat.
• The muscular system supports skeletal position.
• The muscular system protects soft tissue.

Integumentary System

• The integumentary system protects underlying tissues.
• The integumentary system includes all the structures that make up the skin.
• The word "integumentary" derives from the Latin "integumentum".

Nervous System

• The central nervous system includes the brain and spinal cord.
• The peripheral nervous system is the rest of the nervous system.

Endocrine System

• The endocrine system regulates the body's metabolic processes and fluid balances by releasing chemicals (hormones).
• Hormones help manage stress and other bodily stresses.

Cardiovascular System

• The cardiovascular system is the main transportation system in the body.
• The cardiovascular system includes the heart, blood vessels, and blood.
• The cardiovascular system carries oxygen and nutrients.

Respiratory System

• The respiratory system filters warms, and humidifies air.
• Alveoli are the sites of gas exchange between air and blood.
• The respiratory system maintains the proper acid-base balance of the blood.

Lymphatic and Immune System

• The lymphatic and immune system is a drainage system.
• The lymphatic and immune system helps maintain proper fluid balance.
• The lymphatic and immune system protects from infection.
• The lymphatic and immune system produces blood cells.

Digestive (GI) System

• The digestive system breaks down food mechanically and chemically.
• The digestive system absorbs substances.
• The digestive system transports unused materials out of the body.

Urinary System

• The urinary system filters blood and eliminates waste products.
• The urinary system helps maintain proper fluid balance and blood pressure.
• The urinary system helps control the number of red blood cells.

Reproductive System

• The reproductive system produces and transports gametes (sperm and ova).
• The reproductive system produces sex hormones.
• The uterus is the site of development in females.

Homeostasis

• Homeostasis is the relative constancy of the body’s internal environment.
• Physiological processes monitor and maintain equilibrium.
• Internal conditions remain within a narrow range even with dramatic external changes.

Negative Feedback

• Negative feedback is the primary mechanism that keeps a variable close to a set point.
• Negative Feedback require, as a minimum, a sensor and a control center.

Positive Feedback

• Positive feedback causes a change that brings about a greater change in the same direction.
• Beneficial examples of positive feedback include the birthing process.
• Positive feedback loops in nature are often disastrous.
• Shock, fever, and global warming are examples of disastrous positive feedback loops.