Human Biology Chemical Messengers
Human Biology 3A Notes
CHAPTER 4: Chemical Messengers
Homeostasis: the maintenance of a constant internal environment
Homeostasis ensures that the fluid environment of the cells: • Contains the optimum concentration of nutrients, ions, gases and water • Stays at a constant temperature – the optimum temperature for normal cell functioning • Is maintained at the optimum pressure
Feedback system: Negative feedback system:
Negative feedback: Positive feedback:
A situation where the response toa stimulus changes the original stimulus
Where the response to a stimulus brings about a change opposite to, or reduces the effect of, the original stimulus
Feedback that brings about a change opposite to, or reduces the effect of, the original stimulus Feedback that reinforces the original stimulus
Common features of a negative feedback system:
Example:
Stimulus: Receptor: Modulator: the change in environment that causes the system to operate detects the change control center (brain) that processes information from receptor and sends to the effector
Effector:carries out a response counteracting the effect of the stimulus
Response: a response is carried out (action) Feedback: is achieved because the original stimulus has been changed by theresponse
Homeostatic mechanisms are controlled by both the nervous system and the endocrine system.
Nervous system: sends electrical messages to appropriate organs Endocrine system: secrete chemical messengers
Endocrine system is generally slower
Endocrine system: Exocrine glands: Endocrine glands: the body system involved in chemical communication between cells; made up of endocrine glands secrete into a duct that carries the secretion to the body surface or to one of the body cavities secrete hormones into the extracellular fluid that surrounds the cells making up the gland
Hormone: a chemical secreted by an endocrine gland and often carried in the blood that affects the functioning of a cell or organ
Steroid
CHAPTER 4: Chemical Messengers
Homeostasis: the maintenance of a constant internal environment
Homeostasis ensures that the fluid environment of the cells: • Contains the optimum concentration of nutrients, ions, gases and water • Stays at a constant temperature – the optimum temperature for normal cell functioning • Is maintained at the optimum pressure
Feedback system: Negative feedback system:
Negative feedback: Positive feedback:
A situation where the response toa stimulus changes the original stimulus
Where the response to a stimulus brings about a change opposite to, or reduces the effect of, the original stimulus
Feedback that brings about a change opposite to, or reduces the effect of, the original stimulus Feedback that reinforces the original stimulus
Common features of a negative feedback system:
Example:
Stimulus: Receptor: Modulator: the change in environment that causes the system to operate detects the change control center (brain) that processes information from receptor and sends to the effector
Effector:carries out a response counteracting the effect of the stimulus
Response: a response is carried out (action) Feedback: is achieved because the original stimulus has been changed by theresponse
Homeostatic mechanisms are controlled by both the nervous system and the endocrine system.
Nervous system: sends electrical messages to appropriate organs Endocrine system: secrete chemical messengers
Endocrine system is generally slower
Endocrine system: Exocrine glands: Endocrine glands: the body system involved in chemical communication between cells; made up of endocrine glands secrete into a duct that carries the secretion to the body surface or to one of the body cavities secrete hormones into the extracellular fluid that surrounds the cells making up the gland
Hormone: a chemical secreted by an endocrine gland and often carried in the blood that affects the functioning of a cell or organ
Steroid