Chapter 10 Flashcards
Puberty brings about many changes in the human body.
- Both genders get a growth spurt during puberty, & the 2ndary sex characteristics begin to develop.
- Males= the growth of body and facial hair, deepening of the voice, & the development of the genitals.
- Females= the growth of body hair, the onset of their menstrual cycle, & the development of breasts & broader hips.
- All of these developments r timed & controlled by hormones
A hormone is
a chemical made by cells in one part of the body that regulate the processes of cells in another part of the body
- are prduced by the endocrine system
- act as chemical messengers, enabling 1 part of the body to give instructions to another part
- Some cells even self-regulate, producing chemicals to stimulate their own cellular processes
Local regulators are
chemicals like hormones but act on nearby cells, rather than cells some distance away.
Hormones r secreted by…
the cells, tissues, & organs that compose the endocrine system
The endocrine system does what?
Regulates & coordinates organ functions like growth, development, reproduction, behavior, energy metabolism, & water balance. (like the nervous system)
The nervous system & Endocrine system
- Both systems regulate & coordinate body functions.
- r structurally, chemically, & functionally related, but they control organ & tissue functions in diff ways
–> Nervous system: Sends fast electrical signals for rapid responses to the external environment.
–> Endocrine system: Uses slower, longer-acting hormonal responses to control organ and tissue functions. - Nervous system regulates the release of most hormones, ultimately controlling the endocrine system.
Endocrine glands are
ductless secretory organs that secrete their hormones
directly into the blood or extracellular fluid.
–> (In contrast, exocrine glands, like the sweat & salivary glands, release their secretions into ducts that lead outside the body or into the body cavities)
- Hormones circulate throughout the body in blood & other fluids.–> As a result, most body cells r constantly exposed to a wide variety of hormones but only target cells will respond to a specific hormone cuz only they have receptor proteins that recognize & bind to that type of hormone
- Hormones r cleared from the body at a steady
rate by enzymatic breakdown in their target cells, in the blood, or in organs such as the liver or kidneys. –> The breakdown products are reused or excreted
There are more than ____known hormones and local regulators in humans. How do they compare to hormones and regulators in other animals?
60
- Many r identical or very similar in structure & function to the hormones in other animals, tho many animals have hormones not found in humans.
Hormones are identified by their _____________________.
chemical structure
There are 2 main types of Hormones:
- protein hormones, which are water soluble,
- steroid hormones, which are lipid soluble.
- Most hormones fall into one of these two types
A protein hormone is
a hormone composed of chains of amino acids that is water soluble; usually acts on cell membrane receptors
- amino acid chains= 3 amino acids to more than 200
- released into the blood or extracellular fluid by the cells in the endocrine glands where they are made.
- usually hydrophilic: they have an affinity for water & diffuse well through the blood & intercellular fluids
- 1 group of protein hormones= the growth factors, regulates the division & differentiation of many types of cells in the body
A steroid hormone is
a hormone composed of cholesterol that is not very water soluble; usually passes through the cell membrane & acts on receptors inside the cell
- not very soluble in blood but they can pass easily through the lipid bilayer of cellular membranes
–> Combine with hydrophilic carrier proteins to form water-soluble complexes, enabling diffusion into blood & other fluids.
- When it contacts a cell, it is released from its carrier protein.
- passes through the plasma membrane of the target cell & then binds to internal receptors in the nucleus or cytosol.
- Steroid hormones include aldosterone, cortisol, & the sex hormones.
Some steroid hormones have very similar structures but produce very diff effects. Give an example
- ex, testosterone & estradiol, 2 major sex hormones that r responsible for the development of male & female characteristics, respectively, differ only in the presence or absence of a single methyl group
Prohormones
- Many hormones r secreted in an inactive or less active form called prohormones
- Prohormones r converted to active forms by target cells or enzymes in blood or tissues.
- Protein hormones are commonly synthesized as prohormones, which r then converted to the active form in the source cell –> some cases, further conversion occurs once the hormone has been secreted
- Ex, Angiotensinogen, secreted by the liver, is an inactive precursor. –> Cleaved by enzyme to an inactive form of angiotensin, which is activated by angiotensin-converting enzyme (ACE) to regulate blood pressure by increasing it. –> ACE inhibitors r used to manage high blood pressure.
Hormones are usually secreted in relatively ________________, but a process of amplification magnifies their effect. Explain
small amounts
- Once a receptor cell activates a few proteins, these
proteins activate other proteins, each of which activates other proteins, and so on.
- This chain reaction amplifies the effect of the small amount of hormone initially received.
