Probably nothing, but… Go check your plants and in your composition book with the date and time, make any observations. If nothing, put ‘None today’

Response In order for organisms to maintain homeostasis, they must be able to respond to stimuli (both internal and external.) Homeostasis: ‘steady state’, maintenance of an internal balance.

Different ways your body responds to stimuli: Negative Feedback Response: A control mechanism that reduces the stimulus or turn things back around to a ‘set point’. Positive Feedback Response: A control mechanism that amplifies (moves in the same direction as the stimulus) rather than reduces the stimulus. Release of the hormone Oxytocin creates a reaction that stimulates more of it’s own release: Contractions- Oxytocin release- causes more contractions- more oxytocin…all the while increasing in intensity and frequency. If your blood sugar gets too low, your pancreas releases glucagon, which stimulates hydrolysis of glycogen, which raises your blood sugar. If your blood sugar gets too high, your pancreas releases insulin, which sends a message to cells to take in sugar, and for the liver to synthesize and store glycogen.

What would these be? Ripe apples releasing gaseous hormone called Ethylene.

What would these be? Low rainfall in an area causing stomata to close.

Thermoregulation A very important part of homeostasis and negative feedback response for animals is maintaining a temperature within a tolerable range. Internal metabolism and the external environment are the sources of heat for thermoregulation. ENDOTHERMS: Are animals warmed mostly by heat generated by metabolism. Maintain stable body temp even with fluctuations in the environment.

Thermoregulation A very important part of homeostasis and negative feedback response for animals is maintaining a temperature within a tolerable range. Internal metabolism and the external environment are the sources of heat for thermoregulation. ECTOTHERMS: Are animals that gain most of their heat from external sources. Maintain stable body temp even with fluctuations in the environment.

Responding to stimuli and maintaining control of the internal self (especially for animals) is well orchestrated by the endocrine and nervous systems. Response

Hormones : -Chemical signals produced and released from the endocrine system. -Relatively slow-acting (compared to nerve impulses) -Long-lasting effects: seconds, minutes, hours -Growth, Development, Reproduction, Metabolic Processes Neuron Impulses : -Electro-chemical. -Rapid -Direct, immediate response -Movement, Behavior, Sensory processing

When a reflex impulse occurs, the reaction happens very quickly. This is because the impulse does not go all the way to the brain. 1.It travels from the site where the stimulus occurs (Sensory receptor/Sensory Neuron), 2. To the spinal cord (Interneuron), 3. And then back to the site of stimulus, so a reaction can take place. (Motor Neuron)

When a voluntary impulse occurs, you have conscious control over your movement. This involves the brain. 1. Sensory neuron, 2. To the brain (interneuron), 3. Then to the muscle (Motor).

Section 23.3 Summary – pages As these cells lengthen, the stem bends toward the light. The growth of a plant toward light is called phototropism. TROPISM

Section 23.3 Summary – pages Gravitropism is plant growth in response to gravity. Roots that grow down into the soil are able to anchor the plant and can take in water and dissolved minerals. TROPISM Stems usually exhibit a negative gravitropism.

Section 23.3 Summary – pages Some plants exhibit another tropism called thigmotropism, which is a growth response to touch. Because tropisms involve growth, they are not reversible. The position of a stem that has grown several inches in a particular direction cannot be changed. TROPISM Ivy is a good example of a plant that exhibits all three types of tropism.

Section 23.3 Summary – pages A responsive movement of a plant that does not involve growth is called a nastic movement. An example of a nastic response is the sudden closing of the hinged leaf of a Venus’s-flytrap. PLANT RESPONSES