EXAM 3- ch.7 & ch.8

Question 1

what’s the four criteria that make a chemical signal a hormone?

Answer 1

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

Question 2

what is the cellular mechanism of action of hormones?

Answer 2

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

Question 3

what are three classes of chemical hormones? Provide an example

Answer 3

Peptide hormones: derived from proteins (vassopressin)
Steroid hormones: derived from cholesterol, a lipid (cortisol)
amine hormones: derived from amino acids. (melatonin)

Question 4

synthesis, storage and release of peptide hormones work?

Answer 4

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.

Question 5

synthesis, storage and release of steroid hormones work?

Answer 5

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

Question 6

what’s the location of hormone receptors for peptide hormones?

Answer 6

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)

Question 7

what’s the location of the hormone receptors for steroid hormones?

Answer 7

located in cytoplasm or nucleus

Question 8

what are the cellular mechanisms of action of peptide hormones?

Answer 8

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)

Question 9

what are the cellular mechanisms of action of steroid hormones?

Answer 9

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)

Question 10

what are the 2 main groups of AMINE hormones?

Answer 10

TRYPTOPHAN derived:
- melatonin
TYROSINE derived:
-catecholamines (epinephrine, norepinephrine, dopamine)
-thyroid hormones

Question 11

what is the role of the nervous system in the endocrine reflexes? (for insulin)

Answer 11

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)

Question 12

what is the structure and function of the anterior pituitary?

Answer 12

A true endocrine gland. And is responsible for releasing 6 horomones with different functions.

Question 13

what is the structure and function of the posterior pituitary?

Answer 13

An extension of nervous tissue: secretes neurohormones made in hypothalamus & controls many homeostatic functions

Question 14

list the 6 anterior pituitary hormones, which hormones control their release, and what are their primary targets?

Answer 14

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

Question 15

list the 2 posterior pituitary hormones, which hormones control their release, and what are their primary targets?

Answer 15

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

Question 16

Compare long-loop negative feedback for anterior pituitary
hormones to the negative feedback loops for insulin and parathyroid
hormones.

Answer 16

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

Question 17

Explain permissiveness, synergism, and functional antagonism as
they apply to hormones.

Answer 17

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

Question 18

Describe the three most common types of endocrine pathologies.

Answer 18

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.

Question 19

Map the organization of the nervous system in detail

Answer 19

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

Question 20

describe the parts of a neuron and their functions. DRAW IT OUT.

Answer 20

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

Question 21

describe the parts of a synapse and their functions.

Answer 21

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.

Question 22

Name the types of glial cells and their functions.

Answer 22

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

Question 23

How does the G-H-K equation relate to the membrane potential of a cell?

Answer 23

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.

Question 24

what are graded potentials?

Answer 24

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

Question 25

what are action potentials?

Answer 25

Rapid and uniform electrical signal conducted down a cell membrane (“All or none” response). Occurs when the membrane potential of a specific cell rapidly rise and fall. They occur at trigger zone and travel through axon, and only use voltage-gates channels.

Question 26

what is absolute refractory period?

Answer 26

Period for Na channels to reset to original position.
Rising phase and beginning of falling phase

Question 27

what is a relative refractory period?

Answer 27

Period when some of Na channels are reset and K channels open up

Question 28

explain the role of myelin in conduction of action potentials

Answer 28

Myelin speeds up the conduction of action potentials.
Can be made up of schwaan cells within the PNS.
Made up of oligendendrocytes in the CNS.

Question 29

Distinguish between electrical and chemical synapses

Answer 29

Electrical synapses: nerve impulse is transmitted electrically via channel proteins
Chemical synapses: nerve impulse is transmitted chemically via neurotransmitters

Question 30

List and give examples of the seven groups of neurocrine
secretions

Answer 30

1) Acetylcholine: nicotinic and muscarinic cholinergic receptors
2) Amines: serotonin, dopamine, epinephrine and norepinephrine
3) Amino Acids: Glutamate, aspartate
4) Peptides: opioid peptides (endorphines) and substance P
5) Purines: adenosine, adenosine monophosphate (AMP), and ATP
6) Gases: nitric oxide (NO) and carbon monoxide (CO)
7) Lipids: fats, oils, etc. and eicosanoids

Question 31

Describe different patterns for neurotransmitter synthesis,
recycling, release, and termination of action

Answer 31

Neurotransmitter synthesis occurs in the axon terminals of neurons
Release happens when calcium enter axon terminal, which allows neurotransmitter to bind with cell membrane
Recycling allows neurotransmitters to go back into cell and be used again
Termination happens through diffusion and is an enzymatic break down.

Question 32

Compare temporal and spatial summation

Answer 32

Temporal summation is the integration of two graded potentials, one from a presynaptic neuron.
Spatial summation is the integration of currents from nearly stimulated graded potentials.

Question 33

Compare presynaptic and postsynaptic inhibition

Answer 33

Presynaptic inhibition occurs in the axon neuron, and involves the reduction of neurotransmitter release from the presynaptic terminal. Delivers the signal
Postsynaptic inhibition occurs at the postsynaptic membrane and involves changes in the responsiveness of the postsynaptic neuron. Receives the signal

Question 34

how does the simple endocrine response work?

Answer 34

Endocrine cells acts as sensors and integrating centers.
Hormone = output. Its release is regulated by (-) feedback loop
Parathyroid hormone (PTH) controls calcium homeostasis
- PT cells detect low calcium in blood
- so then PTH is released into blood & causes:
- calcium release from bone
- decreased calcium excretion in kidney
- increased calcium absorption by intestine
-once calcium levels rise, PTH is no longer released

Question 35

what are the differences between primary, secondary and tertiary endocrine pathologies?

Answer 35

Primary endocrine pathologies inhibit the action of downstream glands (Problem with the LAST endocrine gland)
Secondary endocrine pathologies indicates problem with pituitary gland (problem with anterior pituitary)
Tertiary endocrine pathologies has to do with the dysfunction of hypothalamus and hormone release (Problem with hypothalamus)

Question 36

what’s a short feedback loop?

Answer 36

A short feedback loop is when pituitary hormones inhibit the release of hypothalamic hormones (negative feedback from the pituitary on the hypothalamus)

Question 37

what’s a long feedback loop?

Answer 37

A long feedback loops when hormones from peripheral endocrine glands inhibit the release of hypothalamic and pituitary glands (negative feedback from a pituitary target gland ont he hypothalamus)