Human Body Tissues and Systems

Learning Objectives

• Different tissue types and their functions are described.
• The functions of the different body systems are identified and described.
• Homeostasis is defined.

What is Tissue?

• A tissue is composed of similarly specialized cells.
• These specialized cells perform a common function in the body.

Four Types of Tissues in the Human Body

• Epithelial tissue lines the body surfaces and cavities.
• Connective tissue supports and bonds body parts.
• Muscular tissue moves the body and its parts.
• Nervous tissue receives stimuli and conducts impulses.

Function of Epithelial Tissue

• Tightly packed cells form a sheet that protects underlying structures.
• Functions may include secretion (glands), absorption, excretion, and filtration.

Connective Tissue

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

Muscle Tissue

• Muscle tissue provides means for movement by and within the body.
• Muscle cells are called muscle fibers.
• These muscle fibers can either be striated or not.

Skeletal Muscle

• Skeletal muscle cells are striated.
• Skeletal muscle is voluntary.

Cardiac Muscle

• Cardiac muscle cells are striated.
• This muscle is involuntary.

Smooth Muscle

• Smooth muscle cells are NOT striated.
• This muscle is involuntary.

What Makes up Nervous Tissue?

• Neurons (nerve cells) conduct impulses/information.
• Sensory input, integration, and motor output are all part of neuron impulses.
• Neuron structure includes dendrites, cell body, and axon.
• Neuroglia are support cells that support and nourish neurons.

Organs

• Organs are made up of two or more types of tissues.
• Organs are organized in a way that accomplishes a task that the tissues cannot do on their own.

Body Systems

• A body system is formed by organs and other structures that work together.
• The system does more than one organ can do on its own.

Skeletal System

• The skeletal system provides support and protection.
• It stores minerals.
• The skeletal system is the site of blood cell production.

Muscular System

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

Integumentary System

• The integumentary system protects underlying tissues.
• It is made up of all the different structures that make 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 comprises the rest of the nervous system.

Endocrine System

• The endocrine system helps to regulate the body’s metabolic processes and fluid balances by releasing chemicals (hormones).
• Hormones help deal with stress and stresses in the body.

Cardiovascular System

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

Respiratory System

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

Lymphatic and Immune System

• The lymphatic and immune system is a drainage system of the body.
• It helps to maintain proper fluid balance.
• It protects from infection.

Digestive (GI) System

• The digestive system breaks down food, mechanically and chemically.
• It absorbs substances.
• Unused materials are transported out.

Urinary System

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

Reproductive System

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

Homeostasis

• Homeostasis is the relative constancy of the body’s internal environment.
• Physiological processes monitor and maintain equilibrium.
• Even if external conditions change dramatically, internal conditions stay within a narrow range.

Negative Feedback

• Negative feedback is a primary mechanism that keeps a variable close to a set point.
• Two components (minimum) include a sensor and a control center.

Positive Feedback

• Positive feedback brings about a greater change in the same direction.
• Beneficial examples include the birthing process.
• Positive feedback loops in nature are usually disastrous e.g. shock, fever, and global warming.