EXAM 3 Flashcards
Cretinism
low level of thyroid hormone
Hyperthyroidism
Too much thyroid hormone
- tired all the time
- eyes bulging
- increased metabolic rate
MCH
Hormone allowing fish to change color when eyes sense different colors
Pituitary gland controls:
maturation of sexual organs
Classical definition of hormones
“chemical substances produced by specialized tissues and transported through bloodstream to other tissues where they elicit a specific physiological response
Limitations of classical definition of hormones
- not all substances that have hormonal activity are produced from specialized tissues
- many hormones have multiple sources
- some hormones act locally without releasing into circulation
Broad definition of hormones
“chemical substances released by one cell and which act on another cell”
- not nutrients
- effective in low concentration
classical endocrine glands
- pineal
- hypothalamus
- pituitary
- thyroid
- parathyroid
- adrenal
- pancreas
- ovary
- testis
Exocrine vs. endocrine gland
exocrine - secretes to a specific destination - excretes to external environment endocrine - ductless gland - secretes into circulatory system
4 types of cell signaling
- direct cell (gap junctions)
- autocrine/paracrine (cell to cell)
- neural (long distance, electrical)
- endocrine (blood stream)
6 classes of chemical messengers
- peptides
- steroids
- amines
- lipids
- purines
- gases
Hydrophilic messenger characteristics
Storage: intracellular vesicles Secretion: exocytosis Transport: extracellular fluids Receptor: transmembrane Effects: rapid
Hydrophobic messenger characteristics
Storage: synthesized on demand Secretion: diffusion across membrane Transport: - short: dissolved in extracellular fluid - long: bound to carrier proteins Receptor: intracellular or transmembrane Effects: slower or rapid
Peptide protein hormones
- hydrophilic • soluble in aq. sol'n • travel to target cell dissolved in extracellular fluid - bind to transmembrane receptors • signal transduction (?) - Rapid effects on target cell
- 2-200 AA long
- Synthesized on rough ER
- stored in vesicles
- secreted by exocytosis
Larger peptide hormones that are later broken apart
preprohormones
AVP
Arginine Vasopressin
Amine Hormones
- Chemicals that possess amine group
- some “true” endocrine hormones
- some neurotransmitters
- some both
- most are hydrophilic
- many effects
examples of amine hormones
- acetylcholine
- catecholamines
- dopamine
- norepiniephrine
- epinephrine
- serotonin
- melatonin
- histamine
- thyroid hormones
Steroid Hormones
- derived from cholesterol
- synthesized on smooth ER or Mitochondria
- hydrophobic
- can diffuse thru plasma membrane
- cannot be stored in cell
- synthesized on demand
- transported by carrier proteins
- SLOW EFFECTS
Three classes of steroids
- mineralocorticoids
- electrolyte balance
- glucocorticoids
- stress hormones
- reproductive hormones
- regulate sex-specific characteristics
Steroid Hormone Characteristics
- Hydrophobic • can diffuse through plasma membrane • cannot be stored in cell • must be synthesized on demand • transported to target cell by carrier protein • bind to intracellular or transmembrane receptors • slow effects on target cell - gene transcription
Target cell communication
Ligand (chemical messenger) binds to receptors on target cell
IGF:
Insulin growth factor
IGF1:
Triggers response
IGF2:
prevents response
Ways to inactivate the Ligand-Receptor complex
- ligand removed by distant tissues
- ligand taken up by adjacent cells
- ligand degraded by extracellular enzymes
- ligand-receptor complex removed by endocytosis
- receptor inactivation
- inactivation of signal transduction pathway
Types of receptors
- ligand-gated ion channel
- receptor enzyme
- g-protein coupled receptor
- intracellular receptors
Intracellular receptors
- ligand diffuses across cell membrane
- binds to receptor in cytoplasm or nucleus
- L-R complex binds to specific DNA sequences
- Regulates the transcription of target genes
3 domains on the intracellular receptor
- Ligand-binding
- DNA-binding
- transactivation
6 major hormones released by the anterior pituitary
- Growth Hormone (GH)
- Prolactin (PRL)
- Thyroid Stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Luteinizing hormone (LH)
- Follicle stimulating hormone (FSH)
Oversecretion of GH
Gigantism - increased GH early in life
Acromegaly - increased GH later in life
Dwarfism can be a result of two different things:
- GH deficiency
- GH receptor insensitivity
Agonist
- Binds to receptor
- Causes a Response
- Many are man-made
Agonist
- Binds to receptor
- Causes a Response
- Many are man-made
Antagonist
- binds to receptor
- does not cause a response
- man-made OR natural
3 main neurohormones (hypothalamus)
- TRH
- GnRH
- CRH
TRH
Thyrotropin-releasing hormone
- 3 amino acids
GnRH
gonadotropin-releasing hormone
- 10 AAs
- stimulate FSH and LH
CRH
ACTH-releasing hormone
- 41 AAs
GHRH
GH Releasing Hormone
- increases at night
- released from hypothalamus into pituitary
GHIH
GH Inhibitory hormone
- goes down at night
released from hypothalamus
GH goes to _____ tissues
all
GH causes release of ____ to ____ cells
IGFs, neighboring
Prolactin
- promotion of lactation
- promotes maternal behavior thru effects on brain
- found in all vertibrates – even ones without mammary glands
6 other effects of prolactin
- osmoregulation
- reproduction
- development
- metabolism
- integument
- behavior effects
Cretenism is caused by…
insufficient thyroid hormone during fetal and neonatal development
ACTH
Adrenocotricotropic hormone
- controls stress response
- goes to adrenal gland
- adrenal gland releases cortisol
Posterior pituitary
- extension of hypothalamus
- neruons that originate in ht terminate in post. pit.
- neurohormones oxytocin and vasopressin synthesized in cell body (ht) and travel in vesicles down axon
- First Order endocrine pathway
AVP:
vasopressin
- binds g protein linked receptor
- activates adenylate cyclase
Triggers insertion of aquaporins in cell membrane via exocytosis
Beta cells of pancreas store
Insulin
Alpha cells of pancreas store
Glucagon
Delta cels of pancreas store
Somatostatin
3 chains of Insulin
A-chain: 21 AA
B-chain: 30 AA
C-chain: 31 AA
_____ cleaved off insulin to form mature insulin
C-chain
insulin favors _____, inhibits _____
Anabolic, catabolic
Isoreceptors
Same hormone, different receptors, different response
Fick Equation
dQ/dt = D • A • (dC/dx)
Diffusion equation
t = x^2/4D
Boyle’s Law
P1V1 = P2V2
Henry’s Law
[G] = Pgas • Sgas
Graham’s Law
Diff. Rate (proportional to)
D• A • ∆Pgas • Sgas/
X • sqrt(MW)
_____ has the same effect as increasing surface area
mixing
In tidal ventilation PO2 can approach the PO2 of ________
exhalant
Bird Lung process
- air enters posterior sacs
- chest compressed, air forced to lung
- chest expanded, air forced to anterior air sacs
- chest compressed, air forced out
each hemoglobin molecule can bind ___ oxygen molecules
4
each red blood cell has ______ hemoglobin molecules
hundreds of
3 methods of CO2 transport in blood
- Dissolved in plasma (7%)
- Carbaminohemoglobin (23%)
- Bicarbonate (70%)
_____ catalyzes formation of bicarbonate
Carbonic Anhydrase
Increasing pH shifts O2 affinity curve to the____
Left, better affinity
physiological processes are ________ sensitive
temperature
ideal temperature range for most animals
0-45ºC
Q10 equation
Rate at (T+10ºC)/rate at TºC
Body heat =
Heat produced + Heat transferred
Fourier’s law:
Q(heat flux) = λ∆T/L
Resistance =
1/conductivity
Thermal conductivity units
W/m/K (watts/meter/kelvin)
Examples of external insulation
- hair
- feathers
- air
- water
Heat Flux =
Metabolic heat production +/- conduction +/- convection +/- radiation - evaporation
poikilotherm
relatively variable body temperature
homeotherm
relatively stable body temperature
ectotherm
environment determines body temperature
endotherm
animal generates internal heat to maintain body temperature
ectotherms include…
all invertebrates, fish, amphibians, reptiles
benefits of ectotherms
- exploit many adaptive zones unavailable to birds and mammals
- low metabolic rate
- suited to periodic shortages in food, water, oxygen
Homeoviscous adaption
ectothermal animals reduce ill effects of temp by changing cell membrane composition
four ways to change cell membrane compostion
- fatty acid chain length
- saturation
- phospholipid classes
- cholesterol content
3 ways to move from low to high membrane fluidity
- shorten the chain length
- unsaturate the chain
- PC -> PE (polar head)
two types of phospholipid remodeling
- in-situ
- de-novo
cell membranes are constantly remodeled by
endocytosis and exocytosis
Physiological mechanisms to maintain homeostatic temperature (ectotherms)
- metabolic compensation
- isozymes (enzymes with same function, but that act at different temps)
- color change
- countercurrent heat exchange (e.g. rete mirable)
HSP
Heat shock protein (chaperone)
Freeze tolerance
some animals allow their tissues to freeze
freeze avoidance
- cryoprotectant: increase in. intracellular solute concentration decreases freezing point
- antifreeze macromolecules (proteins/glycoproteins disrupt ice crystal formation by binding to small crystal and preventing growth)
Regional ectotherms
different areas of the body warming up
temporal ectotherms
different body temps at different times of day
mechanisms to lose body heat
- sweating
- panting
- vasodilation
dormancy
- hibernation
- esternation
Thyroid hormone can ___________ temperature
increase
