EXAM 3- ch.7 & ch.8 Flashcards
what’s the four criteria that make a chemical signal a hormone?
1) hormones are secreted by a cell or group of cells
2) hormones are secreted into the blood
- through secretion
- pheromone: a hormone secreted outside the body
3) hormones are transported to a distant target via blood
4) hormones exert their effects at low concentrations
what is the cellular mechanism of action of hormones?
hormones act by binding receptors. target cell must have appropriate receptors to be able to bind to the hormone.
The hormone receptor binding initiates a cellular mechanism of action.
May act one one or multiple tissues and might cause different effects in different tissues.
HORMONE ACTION must be terminated. Without regulation of hormones, it can be harmful to the body, this ensure limitations of the hormones effects. They are usually degraded by by enzymes in the liver or kidney
what are three classes of chemical hormones? Provide an example
Peptide hormones: derived from proteins (vassopressin)
Steroid hormones: derived from cholesterol, a lipid (cortisol)
amine hormones: derived from amino acids. (melatonin)
synthesis, storage and release of peptide hormones work?
SYNTHESIS
range from 3 amino acids to glycoproteins. They are transcribed and translated in the nucleus
1) amino acids are binded into a peptide chain called a prepohormone. It is directed into ER lumen by signal sequence
2) Within ER, enzymes remove signal sequence, resulting in prohormone.
STORAGE
3) Prohormone goes from ER into Golgi
4) Golgi packs hormone into secretory vesicles and enzymes chop it into active hormone
RELEASED
5) Secretory vesicle releases contents by exocytosis into extracellular space
6) hormone moves into circulation for transport to its target.
synthesis, storage and release of steroid hormones work?
SYNTHESIS
derived from cholesterol within adrenal cortex and male/female gonads.
-Produced in smooth ER & are lipophilic.
STORAGE
-They can’t be stored in vesicles so it’s synthesized as needed and released via simple diffusion.
RELEASED
-Must bind a carrier molecule to be transported in blood; the carriers protect the hormone from degradation
and entering cells.
-Entry of hormone to target cell obeys mass action
what’s the location of hormone receptors for peptide hormones?
binding to cell surface receptors to form complex initiates:
- intracellular signaling (signal transduction)
- most work through cAMP (2nd messenger)
- others work through tyrosine kinase (enzyme receptors)
what’s the location of the hormone receptors for steroid hormones?
located in cytoplasm or nucleus
what are the cellular mechanisms of action of peptide hormones?
lipophobic
binding to cell surface receptors to form complex initiates:
- intracellular signaling (signal transduction)
- most work through cAMP (2nd messenger)
- others work through tyrosine kinase (enzyme receptors)
what are the cellular mechanisms of action of steroid hormones?
their ultimate destination is the nucleus of target cell.
- here it acts as a transcription factor or bind to the DNA; creates genomic effect
does not mediate fast response (takes ~90 min)
what are the 2 main groups of AMINE hormones?
TRYPTOPHAN derived:
- melatonin
TYROSINE derived:
-catecholamines (epinephrine, norepinephrine, dopamine)
-thyroid hormones
what is the role of the nervous system in the endocrine reflexes? (for insulin)
Insulin being regulated:
1) food in intestine activates stretch receptor
2) stretch receptor signals to CNS
*CNS is integrating center
3) CNS signals to the pancreas to release insulin & is sent to target tissues
4) cells take up glucose and blood glucose levels return to normal (decreases)
what is the structure and function of the anterior pituitary?
A true endocrine gland. And is responsible for releasing 6 horomones with different functions.
what is the structure and function of the posterior pituitary?
An extension of nervous tissue: secretes neurohormones made in hypothalamus & controls many homeostatic functions
list the 6 anterior pituitary hormones, which hormones control their release, and what are their primary targets?
1) Prolactin (PRL): milk production. Dopamine triggers its release, and it targets the breast.
2) growth hormone (GH)): metabolism & growth. GHRH & somatostatin triggers its release. Primarily targets the liver.
3) thyroid -stimulating hormone (TSH) - thyrotropin, synthesis and secretion of thyroid hormones. TRH triggers its release. Targets Thyroid Gland.
4) Adrenocorticotophic hormone (ACTH)- adrenocorticotropin, synthesis & release of cortisol. CRH triggers its release. Targets Adrenal Cortex.
5) Follicle-Stimulating Hormone (FSH)- maturation of germ cells in both sexes. GnRH triggers its release. Targets endocrine cells of the gonads (androgens)
6) Luteinizing Hormone (LH)
Males: involved in spermatogenesis (sperm production) & secondary sex characteristics (testosterone production.
Females: involved in follicle growth & secondary sex characteristics (creation of steroid hormones in ovaries)
GnRH triggers its release & targets endocrine cells of the gonads, whcih are testes or ovaries. (estrogen & progesterone)
a follicle is within the ovaries and grows and holds one egg. The follic
list the 2 posterior pituitary hormones, which hormones control their release, and what are their primary targets?
1) VASSOPRESSIN: regulates water balance (antidiuretic hormone- ADH).
-produced in hypothalamus, stored & released from the posterior pituitary gland directly into the bloodstream
- targets the kidney.
2) OXYTOCIN: controls ejection of breast milk & uterine contractions during labor
-produced in hypothalamus, stored & released from the posterior pituitary gland directly into the bloodstream
-targets mammary glands and uterus
both peptide hormones
Compare long-loop negative feedback for anterior pituitary
hormones to the negative feedback loops for insulin and parathyroid
hormones.
Long-loop negative feedback: the hormone released by the endocrine gland feeds back to suppress secretion of anterior pituitary gland and hypothalamic hormones
short-loop negative feedback: the pituitary hormone feeds back to decrease the hormone secretion of the hypothalamus
Explain permissiveness, synergism, and functional antagonism as
they apply to hormones.
synergism: 2 or more hormones interacting w/target & combination result is greater than each individually (additive effect)
Permissiveness: 1 hormone can’t fully exert effects unless a second hormone is present.
antagonism: when 1 hormone opposes the action of another hormone
2 hormones can compete for same receptor
2 hormones acting on different receptors
Describe the three most common types of endocrine pathologies.
hormone imbalances can lead to: disease excess, deficiency, abnormal responsiveness.
ALL can occur anywhere along a pathway.
1) Hypersecretion of a hormone will lead to exaggerated effects. Causes could be cancerous tumors or exogenous hormone treatment (may lead to endocrine gland atrophy)
2) Hyposecretion is when too little hormone is secreted for any reason. Cause is atrophy of a gland due to disease & reduces the negative feedback on the pathway.
3) Abnormal Responsiveness is when target tissue can’t respond properly to hormones. Causes could be down-regulation of hormone receptor, genetic mutation of receptor or signaling molecule. The hormone is present but response is abnormal.
Map the organization of the nervous system in detail
DEMONSTRATES: consciousness, intelligence, emotions
PARTS:
CENTRAL NERVOUS SYSTEM (CNS) - brain and spinal cord
PERIPHERAL NERVOUS SYSTEM (PNS) - afferent and efferent neurons (carry info to and from CNS)
SENSORY DIVISION - info from periphery to CNS (afferent neurons)
EFFERENT DIVISION - info from CNS to periphery (efferent neurons)
SOMATIC MOTOR NEURONS - control skeletal muscle
AUTONOMIC MOTOR NEURONS - controls cardiac and smooth muscle
ENTERIC NERVOUS SYSTEM: Digestive tract, controlled by autonomic nervous system, capable of autonomous action
describe the parts of a neuron and their functions. DRAW IT OUT.
CELL BODY: nucleus and organelles. Control center
DENDRITES: thin branched structure that receives incoming information
AXON HILLOCK: origin of axon
AXON TERMINAL: bulbous terminal of axon that contains mitochondria and membrane
AXONAL TRANSPORT: neurons must carry proteins, chemicals, enzymes, etc down to the terminals
describe the parts of a synapse and their functions.
The synapse is made up of a synaptic cleft, presynaptic and postsynaptic terminal. The presynaptic is at the end of an axon and converts the AP into a neurotransmitter, then releases it. The postsynaptic side receives the neurotransmitter signal released and transducers it. The synaptic cleft is a small space in between the two. The synapse is also where an axon terminal meets its target cell.
Name the types of glial cells and their functions.
1) Schwann Cells - insulates neurons and forms myelin
2) Satellite Cells - supports cell bodies, most ganglion clusters
3) Oligodendrocytes - insulates neurons and forms myelin
4) Microglia - macrophage like immune cells that remove dead cells and foreign invaders
5) Astrocytes - Provides ATP source and provides the bled-brain-barrier support, and several other small roles
6) Ependymal Cells - Creates selectively permeable epithelial ayer of CNS and source of neural stem cells
How does the G-H-K equation relate to the membrane potential of a cell?
The GHK equation calculates the membrane potential that results from the IONS that can cross he cell membrane. The transmembrane ion transport across the plasma membrane is responsible for the membrane potential generation and that the membrane permeability to the individual mobile ions governs the membrane potential behavior.
what are graded potentials?
Variable strength signals that are hyper or depolarized. They occur when chemical signals from other neurons open or close chemically gates ions. They also determine is an action potential is initiated
