Coordination and Control Chapter 18
Lesson 1: the nervous system The nervous system gathers, processes, and responds to information very quickly. Nerve signals can travel 400km/hour!
Stimulus: a change in an organism’s environment that causes a response. Person touches hot pan Person lets go of hot pan Person starts hopping around
Neurons are nerve cells. There are three types of neurons: Sensory: receive information from the environment and relay this to the brain or spinal cord. (the pan is hot!!!) Motor: send information to tissues and muscles (drop the pan) Interneurons: connect sensory and motor neurons (in brain or spinal cord) process the information (the pan is hot, the hand should let go of it)
Neurons are nerve cells. The dendrite receives the information and sends it down the axon where it will usually reach another neuron.
A Synapse is the gap between neurons.
The nervous system has two parts: The central nervous system (CNS) made up of the brain and spinal cord. The peripheral nervous system (PNS) made up of sensory and motor neurons that send information between the CNS and the rest of the body.
The brain has three parts: Cerebrum: the largest part, controls thinking and memory.
The brain has three parts: Cerebellum: found under the cerebrum, it controls coordination, balance, and muscle movement.
The brain has three parts: Brain stem: connects the brain to the spinal cord, this controls involuntary functions like breathing, heartrate, sneezing, coughing, swallowing.
Homeostasis The nervous system senses changes in the environment very quickly and allows the body to respond to these stimuli. Messages get transmitted to other body systems to allow the maintenance of homeostasis. Example: You see the bus driving toward you. You move out of the way. The nervous system works with the skeletal and muscular systems to keep you safe.
Lesson 3: the Endocrine System
The endocrine system Is a group of organs/glands that release chemical messages or hormones into the bloodstream. These hormones carry specific messages to target cells that recognize the hormones based on their protein receptors.
How hormones reach their target cells… Diagram page 658 that shows the path of a hormone
Endocrine glands and the hormones they produce. function pituitary Human growth hormone and others Control of other endocrine glands and growth Thyroid thyroxine Control of energy/metabolism Adrenals adrenaline Help body react to stress testes/ovaries testosterone/estrogen Sex cell development Pancreas Insulin and glucagon Regulate blood sugar levels
Feedback systems Almost all feedback systems in the body are negative: the release of a hormone shuts down more of the hormone being released. It works like a thermostat in your home. When the heat reaches the right temperature, the furnace shuts off. When the temperature falls to a lower temperature, the furnace goes back on.
Positive feedback systems are not often found in living systems. Examples of positive feedback systems would be hormone release during childbirth and milk production in nursing mothers.