Endocrine system Flashcards
What is homeostasis?
A state of relative constancy of the internal environment maintained by a negative feedback loop.
Who is considered the first person to study physiology?
Erasistratus
What did William Harvey demonstrate in physiology?
The heart pumps blood through a closed system of vessels.
What term did Walter Cannon coin in 1932?
Homeostasis
How do homeostatic mechanisms maintain physiological variables?
By comparing their values to a desired, or set point, value.
What role do receptors play in maintaining internal constancy?
They function as sensors that send information to an integrating center.
What is the integrating center?
A specific region in the brain or spinal cord, or a group of cells in an endocrine gland.
What is a negative feedback loop?
A process where changes from a normal range are compensated by reverse changes in effector activity.
True or False: Homeostasis is a completely static state.
False
What is meant by antagonistic effectors?
Control described as ‘push-pull’, where increasing activity of one effector is accompanied by decreasing activity of another.
How is normal body temperature maintained?
By antagonistic effectors such as sweating and shivering.
What is positive feedback?
A mechanism where the action of effectors amplifies changes that stimulated the effectors.
Moving it further away from its set point, rather tahn returning it to equilibrium (homeostasis)
What is the role of the nervous system in homeostasis?
It controls secretion of many endocrine glands and can affect the function of the nervous system.
What are target organs?
Specific organs that can respond to a particular hormone.
What is negative feedback inhibition?
A closed loop system where the secretion of a hormone is inhibited by its own effects.
Define endocrine glands.
Glands that secrete hormones into the blood without ducts.
What is a neurohormone?
A chemical messenger secreted by specialized neurons into the blood.
What types of hormones are derived from amino acids?
Amines
Fill in the blank: Hormones that are derived from cholesterol are called _______.
Steroids
What are glycoproteins?
Proteins bound to one or more carbohydrate groups.
How do lipophilic hormones enter target cells?
They can pass through the plasma membrane due to their lipid solubility.
What is the difference between prohormones and prehormones?
Prohormones are less active parent molecules, while prehormones are inactive until converted in target cells.
What is a synergistic effect?
When two or more hormones work together to produce a particular result.
What is desensitization?
A reduced response of target tissue to the same concentration of a hormone after repeated exposure.