FINALS LEC 2: ENDOCRINE SYSTEM Flashcards
Second messenger system of the body.
- Uses chemical messages (hormones) that are released into the blood.
ENDOCRINE SYSTEM
Hormones control several major processes: (such as)
- Reproduction
- Growth and development
- Maintenance (homeostasis)
- Regulation of metabolism
- Comes from a Greek word meaning “to arouse”
- Produced by specialized cells (secrete hormones into extracellular fluids)
- Blood transfers hormones to target sites
- These hormones regulate the activity of other cells
HORMONES
Chemical Classification of hormones:
(proteins, peptides, amines)
AMINO ACID - BASED HORMONES
STEROIDS
PROSTAGLANDINS
AMINO ACID - BASED HORMONES
Chemical Classification of hormones:
(cholesterol)
AMINO ACID - BASED HORMONES
STEROIDS
PROSTAGLANDINS
STEROIDS
Chemical Classification of hormones:
(highly active lipids)
AMINO ACID - BASED HORMONES
STEROIDS
PROSTAGLANDINS
PROSTAGLANDINS
MECHANISM OF HORMONE ACTION
Hormones affect only CERTAIN TISSUES/ORGANS (target cells or organs)
T OR F?
TRUE
MECHANISM OF HORMONE ACTION
Target cells MUST HAVE SPECIFIC PROTEIN RECEPTORS
T OR F?
TRUE
MECHANISM OF HORMONE ACTION
Hormones binding DOES NOT INFLUENCES the working of the cells.
T OR F?
FALSE
MECHANISM OF HORMONE ACTION
Effects caused by hormones:
- Changes in plasma membrane permeability/electrical state
- Synthesis of proteins, such as enzymes
- Activation/inactivation of enzymes
- Stimulation of mitosis
- Promotion of secretory activity
MECHANISM OF HORMONE ACTION
- DIFFUSE through the plasma membrane of target cells
- Enter the nucleus
- Bind to a specific protein within the nucleus
- Bind to specific sites on the cell’s DNA
- Activates genes that result in synthesis of new proteins
a. Direct Gene Activation: STEROID HORMONE MECHANISM
b. Second-Messenger System:
NONSTEROID HORMONE MECHANISM
Direct Gene Activation: STEROID HORMONE MECHANISM
MECHANISM OF HORMONE ACTION
- Hormone BINDS to a membrane receptor and it does not enter the cell
- Sets off a series of reactions that activates an enzyme catalyzing a reaction that produces a second messenger molecule
- Oversees additional intracellular changes to promote a specific response
a. Direct Gene Activation: STEROID
HORMONE MECHANISM
b. Second-Messenger System:
NONSTEROID HORMONE MECHANISM
Second-Messenger System:
NONSTEROID HORMONE MECHANISM
CONTROL OF HORMONE RELEASE
- Hormone levels in the blood are maintained by __________________
NEGATIVE FEEDBACK
CONTROL OF HORMONE RELEASE
- A stimulus/low hormone levels in the blood TRIGGERS the release of more hormones
T OR F?
TRUE
CONTROL OF HORMONE RELEASE
- Hormone release stops once an appropriate level in the blood is reached
T OR F?
TRUE
THE MAJOR ENDOCRINE ORGANS
- Approximately the size of pea
- Hangs by a stalk from the hypothalamus
- Protected by the sphenoid bone
- Has 2 functional lobes
PITUITARY GLAND
PITUITARY GLAND 2 FUNCTIONAL LOBES
- glandular tissue
- “Master endocrine gland”
- Releases 6 hormones (2 affect nonendocrine targets & 4 stimulate other
endocrine glands [tropic hormones])
Proteins (or peptides)
Act through second-messenger
systems
Regulated by hormonal stimuli,
mostly negative feedback
ANTERIOR PITUITARY
POSTERIOR PITUITARY
ANTERIOR PITUITARY
PITUITARY GLAND 2 FUNCTIONAL LOBES
- nervous tissue
- Not and endocrine gland, acts only as a
storage area for hormones made by
hypothalamic neurons
1. Oxytocin
2. Antidiuretic hormone (ADH) or
vasopressin
ANTERIOR PITUITARY
POSTERIOR PITUITARY
POSTERIOR PITUITARY
THE MAJOR ENDOCRINE ORGANS
- Hormonal release of the anterior pituitary is controlled by releasing hormone & inhibiting hormones produced by ___________
HYPOTHALAMUS
THE MAJOR ENDOCRINE ORGANS
- Found at the base of the throat
- Consists of 2 lobes & a connecting isthmus
- Produces 2 hormones:
a. THYROID HORMONE (major metabolic hormone
b. CALCITONIN
THYROID GLAND
THE MAJOR ENDOCRINE ORGANS
- TINY MASSES on the posterior of the thyroid
- Chief cells secrete parathyroid hormone
(chemical class: PEPTIDE)
Stimulate osteoclasts to remove calcium from bone
Stimulate the kidneys & intestine to absorb more calcium
Raise calcium levels in the blood
PARATHYROID GLANDS