Sensory System Continued

Transcription

1 Sensory System Continued

2 Skin The skin is the largest organ of the body, covering its entire surface Technically skin is no longer the largest organ. it s the interstitium What is the skin s purpose?

3 Purpose of Skin The skin has many functions: Protects the inner organs and cells Shields us from harmful UV rays

4 Purpose of Skin The skin has many functions (cont d): Excretes waste (e.g. sweating) Protects from foreign bodies like bacteria Temperature regulation Insulation and evaporative cooling

5 Purpose of Skin The skin has many functions (continued): Makes vitamin D Helps to sense the environment Pressure, pain, temperature Communication Health and emotions

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7 Structure of the Skin The skin is composed of three different layers: Epidermis Dermis Hypodermis (subcutaneous layers)

8 Hair shaft Pore Epidermis Arrector pili muscle Hair follicle Oil gland Hair root HF receptor Adipose tissue Sensory nerve fibre Dermis Hypodermis Sweat gland Pacinian corpuscle

9 Epidermis The epidermis has a dead layer and a living layer The dead layer is the outermost layer Atmospheric pressure causes the cells to burst and die The living layer is underneath A layer of cells that are constantly dividing New cells push old cells towards the surface This helps in the healing process

10 Epidermis The lower layer also contains the melanin The pigment that gives skin its colour and helps protect us against the sun s UV rays Tanning is a result of more melanin being produced due to sun exposure Keep in mind that too much sun exposure can lead to mutations in the cells that contain the melanin which may cause cancer!

11 Epidermis The epidermis is our main line of defense against bacteria invasions and other environmental dangers

12 Dermis The dermis is where you will find: Sensory receptors Blood vessels Sebaceous glands Secrete sebum (oil) to protect the skin Keeps in moisture and waterproofs Sweat glands Produce sweat that is then carried to the surface via the pores Hair follicles

13 Hypodermis Also sometime called the subcutaneous layer The hypodermis is mostly made up of adipose tissue (fat cells) The fat cells act not only as an energy reserve but also as a thermal insulator

14 Sensory Receptors There are three different types of sensory receptors in the epidermis: Tactile sensory receptors for touch and pressure Thermal sensory receptors for heat and cold Pain sensory receptors to indicate pain

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16 Sensory Map The different sensory receptors are not spread out evenly over the body Ex: The cheeks and underside of the wrists are more sensitive to heat The soles of the feet are more sensitive to pressure

17 Taste and Smell

18 The Nose What is its function? Smelling Inhaling and exhaling

19 Nasal Cavity Olfactory cilia Olfactory epithelium Olfactory Bulb Olfactory Nerve Pharynx Nostril Tongue

20 Smelling The nose is the organ associated with smell and odour The nerve cells associated with smell are called olfactory cilia Most of these nerve cells are concentrated in the olfactory bulb at the tip of the olfactory nerve

21 Smelling Although we re very good at detecting smells we are generally poor at identifying them We are used to identifying what we see and hear but not what we smell

22 What is Smell good for? We use our sense of smell to gather information from the world around us, such as: Food Danger (ex: fire, toxic chemicals, etc) Loved ones Pheromones (?)

23 Smell and Memory Smell is also strongly associated with memory Scientists believe that since a mixture of particular smells is more novel than shapes for example, smells can often have strong ties to particular memories

24 Tongue What is the function of the tongue? Has the sensory receptors for taste Helps move food around for chewing (mastication) Used to swallow food Important in speech

25 Tongue

26 Tongue Anatomy All over your tongue there are little bumps called papillae Within some of these papillae are located the taste buds Taste buds are the sensory receptors for taste on the tongue

27 The words taste and flavour are often used interchangeably But humans can only detect 5 different tastes: Sweet Sour Salty Bitter Umami What is the difference between taste and flavour?

28 Taste and Flavour Flavour is actually the interaction between taste and smell It is said that only 10% of flavour comes from the sense of taste, the other 90% is from the smell

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30 Taste Receptors Scientists no longer believe that taste buds are spread out in a particular pattern on the tongue They now believe that all taste buds can experience all five tastes

31 There are also other receptors on the tongue to detect: Temperature Hot and cold Discomfort Prickling feeling Spiciness Tactile properties Texture of food Other Receptors