Ch. 8 Cell Structure & Function Lesson 2 How are Cells Specialized?

Different Cells for Different Jobs All multicellular organisms have specialized cells that work together. Complex organisms have many types of cells. Each cell has special structures that allow it to carry out specific tasks. A group of cells that has a common structure function is called a tissue. Epithelial tissues: *sheet of cells that cover surfaces *line certain body cavities and blood vessels *usually smooth

Connective tissues: *join other tissues together *stores fat and makes blood cells *includes bone, blood, and cartilage *made of specialized cells and fibers that stick to living cells Muscle tissues: *work together to move body *create movement in one direction only (either getting longer or shorter) Nervous tissue: *produces electrical impulses and sends signals *routed through nervous tissue *some send signals while others protect and provide with nutrients

Body functions performed by special structures called organs Organs: *made up of several tissue types that work together to perform one or more functions *example-plant’s leaves, roots, flowers Three human organs: *brain- *heart- *liver- *skin-protect from injury and retain moisture Some organs perform more than one function *kidneys-remove waste and control blood pressure

Relationship among cells, tissues, and organs *tissues are groups of cells with common structures and functions *organs are made of different types of tissues that work together Organ Systems Groups of organs that work together to perform complex tasks The more complex the organism, the greater the number of organ systems needed to survive. Humans have 11 organ systems. Some work for more than one organ system.

Circulatory system Carries hormones made in the endocrine system throughout the body Carries blood and oxygen to the body and removes carbon dioxide and other wastes Helps keep body temperature constant Includes heart, arteries, veins, and blood Connects to the Urinary system at the kidneys *helps regulate water and salt in blood, as well as remove liquid wastes Musculoskeletal system Supports all parts of body and allows movement of different parts Bones anchor body parts and provide structure

Contracting your muscles make body parts move Generates warmth for body (reason why you feel warmer when you exercise) Nervous system Brain is headquarters of nervous system Senses feed information into brain Brain process and responds to information by sending signals down nerves to muscles Brain control other organ systems Respiratory system Brings oxygen into body Removes carbon dioxide from body

Endocrine System Chemical messenger system that makes and sends out hormones throughout the body Hormones have many functions *act as messages *travel through bloodstream *picked up only by certain cells *regulating growth and blood sugar Growth hormone-cause dramatic changes in muscles and bones as you grow Plants use hormones to control growth and other functions

What makes a multi-celled organism different from one that is single-celled? Only multi-celled organisms have cells that work together to form specific functions.