human body systems

Question 1

what is the integumentary system?

Answer 1

1. main organ: skin.
2. skin is composed of three layers; epidermis made up of epithelial cells (thinnest layer) which forms a tough, water-resistant layer. dermis (thickest layer) contains blood vessels, nerves glands, hair follicles and some tiny muscles. sweat glands produce sweat, sebaceous glands produce sebum. hypodermis is under the dermis layer, loosely connects to the muscles and bones under the skin. contains fat cells, which helps to insulate the body.
3. roles:
   - the skin is a barrier
   tough, water-resistant epidermis protects the organism and stops harmful microorganisms from entering the body. chemicals produced by sweat and sebaceous glands kill bacteria and fungi that might grow on the surface of the skin. the epidermis helps to regulate the movement of water into and out of the body. the layer of fat cells in the hypodermis acts as a cushion against minor knocks
   - helps to regulate temp
   contains many receptors which detect changes in temp. blood vessels in skin change diameter to help regulate temp. hairs on the skin stand up or lie flat to help regulate temp. sweat glands product sweat when the body is hot, sweat cools the body as it evaporates from the skin.
   - removes wastes
   excretes waste products like salts. excess nutrients like vitamins can also be lost in sweat and oils
   - senses the environment
   contains many diff receptors that detect a range of diff factors

Question 2

what is the respiratory system?

Answer 2

1. supplies the body with oxygen and removes carbon dioxide
2. nose, pharynx, trachea, bronchi, bronchioles, lung, alveoli and diaphragm
3. nose: warms and humidifies the air, contains sticky mucus and cilia to trap and move foreign particles to the pharynx to be swallowed
   pharynx: serves as a passage for air, pharynx -> larynx -> trachea
   trachea: lined with ciliated mucosa which propels debris and mucus upwards and away from the lungs
   bronchi: lead to lungs, each divides into smaller passageways called bronchioles
   alveoli: one-cell thick, surrounded by a dense network of capillaries. o2 and co2 are exchanged in the alveoli
4. pulmonary ventilation (breathing): caused by changes in air pressure within the lungs, air moves from high to low pressure.
5. inspiration: (requires energy) diaphragm muscle contracts and pulls downwards, intercostal muscles contract, volume of thoracic cavity increases, air pressure inside the lungs decreases, air moves into the lungs from outside (where air pressure is higher).
6. expiration: (doesnt require energy) diaphragm muscle relaxes and arches upwards, intercostal muscles relax, volume of thoracic cavity decreases, air pressure in lungs increases, air moves out of the lungs (where air pressure is lower).