Nervous & Endocrine System

Transcription

1 3/19 HW Day 1 Read pages Complete Vocab. on pg 897 Aim: What is Regulation? Do Now: What 2 organ systems are involved in regulation? Nervous & Endocrine System Regulation: The control and coordination of all the life functions. All organisms must maintain homeostasis and therefore respond to changes in their environment (stimuli) What is reaction time? 1. The amount of time it takes you to respond to a stimulus. It is important to help protect us from danger. Mar 11 1:44 PM 1

2 Regulation: The control and coordination of all the life functions. All organisms must maintain homeostasis and therefore respond to changes in their environment Irritability: the ability of a cell to respond to its environment Ex: Protists: Paramecium, Euglena, Ameba Mar 10 9:28 AM 2

3 What is the function of the Nervous System? A system of nerve cells (neurons) that Carry electrochemical messages all over thebody Mar 13 7:36 PM 3

4 What is a neuron? A nerve cell (basic unit of N.S.) carry electro chem. messages. The Nerve Cell (NEURON) A Dendrites Dendrites E Terminal Branches Synaptic knob B Nucleus Nucleus C D Cell Body body Axon Axon F G myelin Schwann terminal branches Cell (axon) Myelin sheath Mar 13 8:24 PM 4

5 What is an impulse? An electrochemical message that travels down a neuron A wave of depolarization Impulse= Action Potential: a) Resting membrane potential (RMP) at 70mV. Na+ on outside and K+ on inside of cell b) As depolarization reaches threshold of 30mV, the action potential is triggered a Na+ rushes into cell. Membrane potential reaches +30mV on action potential c) Propagation of the action potential at 110 m/sec (which is 225 mph) d) Repolarization occurs with K+ exiting the cell to return to 70mV RMP e) Return of ions (Na+ and K+) to their extracellular and intracellular sites by the sodium potassium (Na+K+) pump Feb 27 1:20 PM 5

6 animation the_nerve_impulse.html cells/neuron structure Outside How does an impulse travel down a neuron? Axon inside resting state. resting Impulse in an axon [impulse] (Change in charges A depolarization of the axon passes through it until the end of the axon Feb 28 12:06 PM 6

7 How does an impulse travel down a neuron? cell body Nucleus Dendrites Axon Depolarization of membrane Synapse myelin Muscle [effector] during depolarization another Action-Potential. Cannot pass through the Axon period Refractory Period = the time it takes the membrane to go back to the resting state. (impulse) this is called the refractory Feb 28 10:21 AM 7

8 All or None Theory of Impulse Activity 1 sec thresholdthe minimum strength of a stimulus that causes an impulse to travel down a neuron (A. P.) if not reached No impulse if reached an impulse Low threshold [weak] High threshold Low threshold [strong] Strength of stimulus is shown in 2 ways High Threshold Feb 28 10:20 AM 8

9 Synapse: the location or space at which a neuron can transfer an impulse to another cell(the gap between neuron and another cell) Synapse Mar 13 8:40 PM 9

10 Transmission at the Synapse Mar 15 6:52 PM 10

11 How does an impulse travel from cell to cell? Neurotransmitter Action Mar 15 6:52 PM 11

12 Neurotransmitters: Chemicals used by a neuron to transmit an impulse across a synapse to another cell. Mar 15 7:02 PM 12

13 Neuromuscular Junctionthe synapse between a neuron and the muscle. Mar 20 7:42 PM 13

14 Attachments Neurons_.asf The_Poli.asf