Homeostasis: Regulation and Control Chapter 8

Key words… Homeostasis Stimuli Receptors Chemoreceptors Mechanoreceptors Photoreceptors Thermoreceptors Pain receptors Interstitial fluid

Homeostasis How the body maintains a stable internal environment / keeps the body within tolerable limits despite external changes

Detecting Stimuli (p212-213) Production of signal Detection of signal Transfer of signal to target Response to signal by target Switching off signal once it has been responded to Your notes: answer these questions in full sentences. You can edit the slides, type them on word or write it down. Where can signals come from? Give three examples What is a stimulus? Write down a definition of this word and give examples What are receptors? Write down a definition What are the five main types of receptor? What do these receptors specifically do?

Signals from the external and internal environments Exteroreceptors Located at or near the external surface of the body. Sensitive to stimuli outside the body. Monitor the external environment. Hearing, vision, smell, taste, touch, pressure, vibration, temperature, and pain. (know examples!)

Signals from the external and internal environments Interoreceptors Located in blood vessels, visceral organs, muscles, and the nervous system. Monitor the internal environment. Usually not consciously perceived; increase in carbon dioxide levels or decrease in pH levels can be detected by interoreceptors

You should have read pages 212 – 214. If not, do it NOW! Then answer questions on page 214. Yes, all of the questions! Don’t make me bite you. I can bite through bone, face tumour or not!

Key words… Homeostasis Stimuli Receptors Chemoreceptors Mechanoreceptors Photoreceptors Thermoreceptors Pain receptors Interstitial fluid Do you know these words? No? You should ! Make flash cards or a glossary to help you remember them. They are important!! DON’T MAKE ME BITE YOU!

The Nervous System

Key words… Central nervous system Peripheral nervous system Sensory neurons Motor neurons Interneurons Effectors Axon Myelin sheath Node (of Ranvier) Somatic nervous system Autonomic nervous system

Fast control: the nervous system Read pages 214 – 217 carefully Copy diagram 8.5b on page 215 (FYI visceral means subconscious/automatic division of the nervous system) Copy diagram 8.6 on page 217

Fast control: the nervous system Still a bit confused about the divisions of the nervous system? Check out this short clip to help you go through it. Gotta love YouTube! https://www.youtube.com/watch?v=q3OITaAZLNc

Activity Go to this link and read pages 1 -2 http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/responses_to_environment/thenerv oussystemrev1.shtml It is important that you know the different parts of a neuron and can identify them in diagrams. Draw a diagram to help you remember the different parts.

You should have read pages 214 – 217. If not, do it NOW! Notes You should have read pages 214 – 217. If not, do it NOW! Then answer questions on page 217 – these will be your notes on this section so do a good job!

Mini Review Complete page 92 of your WACE Study guide You can make electronic flash cards on word by downloading a template (http://www.class-templates.com/vocabulary-flash- cards.html ) or just write directly into the book Use all your resources to make sure you get the answer right

Slow control: the endocrine system Hormones are chemical substances such as proteins, fatty substances, steroids and amino acids In vertebrates they are secreted directly into the bloodstream from ductless glands Hormones target and activate specific organs/receptors to cause an effect

Is it just me or are this guy’s lips creeping you out a bit?! Activity: Copy and complete the table on page 218 – you can incorporate this into a poster using page 219 or make flash cards or just copy the information You MUST know these examples and exactly what they do for your exam

Why do cells and organisms need to respond? Development, Growth and Reproduction Zygotes constantly change, genes become switched on/off, cells programmed to die (apoptosis) and differentiate to become more specialised Certain processes occur due to changes in the internal and external environments

Why do cells and organisms need to respond? Hormones Responding to changes and correcting changes is an essential role to maintain levels within the body between tolerable limits E.g. pH, CO2 concentration, H+ ion concentration and blood glucose concentrations (know these examples inside and out!) Being able to respond to changes in the external environment while maintaining a stable internal environment is essential for life

Then answer questions on page 220. Yes, all of the questions! So by now you know I want you to have read the pages I told you to read… Then answer questions on page 220. Yes, all of the questions! I know what I’m talking about here – I haven’t evolved in millions of years so I’m the boss. And I can totally bite you.