LO3 PDF: Biology Study Guide

Friday, January 17, 2025 7:17 PM LO3 Page 1 LO3 Page 2 LO3 Page 3 Thursday, January 23, 2025 4:32 PM LO3 Page 4 Thursday, January 23, 2025 4:42 PM LO3 Page 5 LO3 Page 6 T...

Friday, January 17, 2025 7:17 PM LO3 Page 1 LO3 Page 2 LO3 Page 3 Thursday, January 23, 2025 4:32 PM LO3 Page 4 Thursday, January 23, 2025 4:42 PM LO3 Page 5 LO3 Page 6 Thursday, January 23, 2025 5:05 PM LO3 Page 7 LO3 Page 8 Thursday, January 23, 2025 5:20 PM LO3 Page 9 Thursday, January 23, 2025 5:39 PM LO3 Page 10 Friday, January 24, 2025 1:49 PM LO3 Page 11 Friday, January 24, 2025 1:53 PM LO3 Page 12 Friday, January 24, 2025 2:01 PM LO3 Page 13 LO3 Page 14 Friday, January 24, 2025 2:13 PM LO3 Page 15 Friday, January 24, 2025 2:17 PM LO3 Page 16 Friday, January 24, 2025 2:25 PM LO3 Page 17 Friday, January 24, 2025 3:26 PM LO3 Page 18 LO3 Page 19 Friday, January 24, 2025 3:36 PM LO3 Page 20 Friday, January 24, 2025 3:46 PM LO3 Page 21 Friday, January 24, 2025 4:11 PM LO3 Page 22 LO3 Page 23 Friday, January 24, 2025 5:14 PM LO3 Page 24 Friday, January 24, 2025 5:22 PM LO3 Page 25 LO3 Page 26  Friday, January 24, 2025 5:45 PM Each hair develops from epidermal cells at the base of a tube- like depression called a hair root. The shaft projects above the surface of the skin and consists of dead, keratinized epidermal cells. A small smooth muscle called the arrector pili or pilomotor is attached to each hair follicle. Pili is Latin for hair and motor means to move (moving). It reacts to fear and cold, causing each hair to stand up resulting in “goose bumps.” Nails are modifications of the epidermis and function to protect the underlying tissue and the ends of the fingers and toes. At the base of each nail is a small extension of the upper layer of epidermis. This “little skin” is called the cuticle. Epidermal cells in the nail contain keratin which is harder than that found in the epidermis and hair follicle. Sebaceous glands lubricate the hair and skin by producing and secreting a lipid substance called sebum, commonly referred to as oil. The sebaceous gland is an exocrine gland. The oil is excreted into hair follicles and works its way up to the surface of the skin and hair. At the surface it lubricates the hair and skin keeping it soft, pliable, relatively waterproof, and less likely to crack or break and allow bacteria to enter. We are constantly losing body water through sweating although we remain unaware of the process. Over a litre of water per day is lost in this way. Sweat is mostly water LO3 Page 27 water per day is lost in this way. Sweat is mostly water contains small quantities of salt and wastes. The dermis of the skin contains two kinds of exocrine sweat glands, eccrine and apocrine glands. LO3 Page 28