Human Body Introduction

Your body There are nearly a hundred trillion cells that make up the human body. Every cell is an independent unit and an interdependent part of a larger community. All the body systems work together so the body functions properly.

Levels of Organization (copy the pyramid) An organism is a living thing made of a group of organs systems. Organ systems are living things made of a group of organs that contribute to a specific function within the body. Organs are living things made of tissues that work together to perform a specific, complex function. Tissues are living things made of a group of cells with similar structures and functions. Cells are the smallest unit of life.

Types of Tissues Different tissue types work together within organs: Muscle tissue (most abundant): controls internal movements of materials (ex: blood, food) Epithelial tissue: closely packed cells covering the surface of the body and line internal organs (ex: inside chambers of heart, glands) Connective tissue: holds organs in place and binds different parts of the body together (ex: tendons, ligaments) Nervous tissue: receives messages from the body’s external and internal environments, analyzes the data, and directs response (ex: controls heart beat)

11 Systems The eleven organ systems of the human body work together to maintain homeostasis. 1. Nervous 7. Integumentary 2. Respiratory 8. Digestive 3. Excretory 9. Skeletal 4. Muscular 10. Circulatory 5. Endocrine 11. Reproductive 6. Lymphatic

Figure 35-2 Human Organ Systems Part I Section 35-1 Nervous System Integumentary System Skeletal System Muscular System Circulatory System

Figure 35-2 Human Organ Systems Part 2 Section 35-1 Respiratory System Digestive System Excretory System Endocrine System Reproductive System Lymphatic System

Section 35-1 Respiratory System Digestive System Excretory System Endocrine System Reproductive System Lymphatic System

11 Functions Nervous: coordinates the body’s response to change in the internal and external environments. Integumentary: serves as a barrier against infection and injury, helps to regulate body temperature, provides protection against UV radiation from the sun Respiratory: provides oxygen needed for cellular respiration and removes excess carbon dioxide from the body

11 Digestive: converts foods into simpler molecules that can be used by the cells of the body, absorbs food Excretory: eliminates waste products of metabolism from the body, maintains homeostasis Skeletal: supports the body, protects internal organs, allows movement, stores mineral reserves, provides a site for blood cell formation

11 Functions (continued) Muscular: works with skeletal system to produce voluntary movement, helps to circulate blood and move food through the digestive system Circulatory: brings oxygen, nutrients, and hormones to cells, fights infection, regulates body temperature Endocrine: controls growth, development, metabolism, and reproduction

11 Functions (continued) Reproductive: produces reproductive cells (in females, nurtures and protects developing embryo Lymphatic: helps protect the body from disease, collects fluid lost from blood vessels and returns the fluid to the circulatory system

Interest Grabber Homeostasis While walking along a dusty path, you begin to cough. As you continue your walk, a small insect comes flying toward you. You blink and then duck so that it misses you. These actions are just a few examples of homeostasis. Homeostasis is the process by which organisms keep internal conditions relatively constant despite changes in their external environments.

Feedback Inhibition Thermostat senses temperature change and switches off heating system Heating system turns on Room temperature decreases Thermostat senses temperature change and switches on heating system

Feedback Inhibition The process by which the product of a system shuts down the system or limits its operation. When the system is switched on, it produces a product that changes the internal environment = “feedback” When the change (feedback) is detected, it shuts down the system = “inhibition” This system is usually automatic and very stable.

Nervous System The nervous system consists of the _____________, ________________ and a network of _____________ T / F Our nerve cells begin to die when we are born. Does the dendrite bring a nerve message TO or AWAY from the body of the nerve?