Control of Muscle Contraction Skeletal muscles are useful only if the contract in a controlled fashion Neuromuscular junction: point of contact between a motor neuron and a skeletal muscle cell
Control of Muscle Contraction Acetylcholine: neurotransmitter that diffuses across a synapse and produces an impulse in the cell membrane of a muscle cell
How Muscles and Bones Interact Tendon: tough connective tissue that joins skeletal muscles to bones They pull on bones and make them work like levers
The Integumentary System Skin and its related structures (hair, nails and some glands) A barrier against injection and injury
The Integumentary System Helps regulate body temperature Removes waste products from the body Provides protection against UV radiation from the sun
The Skin The largest component of the integumentary system Contains several types of sensory receptors for pressure, heat, cold, pain Two main layers
The Skin: The Epidermis Outer layer of the skin Two layers: outer dead cells, inner living cells Keratin: tough, fibrous protein found in skin, what the dead cells help make Melanin: dark-brown pigment found in skin
The Skin: The Dermis Innermost layer of skin Lies beneath the epidermis Contains collagen fibers, blood vessels, nerve endings, glands, sense organs, smooth muscles and hair follicles!!!
The Skin: The Dermis Contains 2 major types of glands: Sweat Sebaceous/Oil
Hair Made mainly of keratin Covers almost every exposed surface of the body Hair follicles: tube-like pocket of epidermal cells that extends into the dermis; cells at the base of hair follicles produce hairs
Nails Made mainly of keratin Protect the tips of the fingers and toes