Final Exam Flashcards
What are the three systems governing homeostasis ?
Negative feedback
Redundancy
Behavioral homeostasis
What is the system that is regulating body temperature ?
Thermoregulation
What is happening if there is a deviation from the desired range in thermoregulation ?
There will be compensatory actions trying to maintain the set zone.
Regarding the set zone, what can happen if we are fighting an infection ?
The set zone will be higher than usual to fight the infection.
What happen if the body temperature is too hot ?
Proteins begin to lost correct shape, link together, malfunction or die (denaturing)
What happen if the body temperature is too cool ?
Chemical body reactions slow down
What happen if the body temperature is very low ?
Ice crystals form damaging cell membrane
What system is known to compensate the loss of functions by the remaining parts ?
Redundancy
What thermoregulation system is related to behavior ?
Behavioral homeostasis
What are the three types of behaviors that ectotherms and endotherms use to regulate temperature ?
They can:
Change exposure of the body surface (huddling
Change external insulation (using clothes or nests)
Change surroundings (moving into the sun, shade…)
What is the difference between an endotherms and ectotherms ?
Endotherms are regulating their body temperature by internal metabolic processes (mammals and birds)
Ectotherms are regulating their body temperature by the environment (snakes, bees)
What is the system that usually young species use to regulate their body temperature ?
Cooperative homeostasis
What is the fluid space of the body that is contained within cells ?
Intracellular compartment
What is the fluid space of the body that exists outside the cells ?
Extracellular compartment
What are the channels spanning the cell membrane that are specialized for conducting water molecules into or out of the cell ?
Aquaporins
What is the movement of water molecules that occurs when semipermeable membrane separates solutions with different concentrations of solute ?
Osmosis
What is the name of the physical force pushing or pulling water across membrane ?
Osmotic pressure
What is the number of solute particles per unit volume of solvent ?
Osmolality
A solution having a similar concentration of solute to solvent inside and outside cell is an… ?
Isotonic solution
What is a solution which has a higher solute concentration than that found in interstitial fluid and blood plasma ?
Hypertonic solution
What is a solution which has a lower solute concentration than that found in interstitial fluid and blood plasma ?
Hypotonic solution
What will happen to cells if placed in a hypertonic solution ?
Inside of the cell becomes dehydrated because of osmosis (water will cross the semipermeable membrane leading to equal concentration of solute on both solutions)
Which system carefully monitors
extracellular compartment to determine if
we should drink ?
The nervous system
How the body retains water in the body ?
By releasing aldosterone from the adrenal glands. Aldosterone directly stimulates the kidneys to conserve Na+ rather than dumping it into the urine. (Salt homeostasis)
What are the two states signaling that water is needed ?
Osmotic thirst (Higher concentration of solute in the extracellular compartment)
Hypovolemic thirst (Reduction in VOLUME of extracellular fluid) Concentration is not changed
What is an example that can triggered an osmotic thirst ?
Eating salty foods
Which neuron in the hypothalamus that is monitoring the concentration of the extracellular fluid ?
Osmosensory neuron
Which organ monitors the composition of body fluids ?
The circumventricular organ
What are the two circumventricular organs ?
Organum vasculosum of the lamina terminalis (OVLT)
Subfornical organ (SFO)
What vasopressin is important for ?
Water conservation
Which receptor detect the reduced blood pressure in the body ?
Baroreceptors
What happen when baroreceptors of the kidneys detect a reduced blood pressure ?
Kidneys release renin, triggering an hormonal cascade that culminates in the circulation of Angiotensin II.
Angiotensin II has several water-conserving actions: Blood vessels constricts (because there was a drop in blood pressure), vasopressin is released, aldosterone is released and than circumventricular organs trigger drinking.
What is the basal metabolism ?
The consumption of energy by the basic life-sustaining functions of the body
True or false.
Metabolic rate adjusts in response to
changes in nutrition.
True.
Metabolic rate adjusts in response to
changes in nutrition
• So resist to losing or gaining weight
• For example, at start of diet, the basal
metabolic rate will fall to prevent losing
weight
What is the principal sugar used for energy ?
Glucose
Which type of cells can take glucose without the aid of insulin ?
Brain cells (neurons)
What is essential for the utilization of glucose by the body ?
Insulin
What happen to glucose every time we eat a meal ?
The foods are broken down and glucose is released into the bloodstream.
What are the three mechanisms that stimulate insulin release ?
Cephalic phase: Sensory stimuli from food (sight, smell and taste) evokes a conditioned release of insulin in anticipation of glucose arrival in the blood
Digestive phase: Food in stomach and intestines causes gut hormones release, which stimulates the pancreas to secrete insulin
Absorptive phase: Glucodetectors in the liver detect glucose entering the bloodstream and signal the pancreas to release insulin
What happen when insulin is released ?
Enables the body to use glucose immediately and the extra glucose is converted into glycogen, which is stored in the liver and muscles.
How is the liver communicated with the pancreas ?
Via the nervous system
Informations from the glucodetectors in the liver travels via which pathway ?
Via the vagus nerve to the nucleus of the solitary tract (NST) and then to the hypothalamus
*This system informs the brain of circulating glucose levels and contributes to hunger
What is the name of the process by which the insulin converts glucose into glycogen ?
Glycogenesis
When glycogen is stored in liver and skeletal muscles, which type of storage is this ?
Short-term storage
When fats are deposited in fat-storing cells forming adipose tissues, what type of storage is it ?
Long-term storage
How can the body take out glucose from storage ?
By glycogenolysis
Glucagon (pancreatic hormone) mediates the conversion of glycogen into glucose.
Under conditions of prolonged food deprivation, fat can be converted into… and… ?
Glucose and ketones
True or false.
The hypothalamus is important for regulation of metabolic rate, food intake and body weight.
True.
Why if we injected a large dose of insulin doesn’t produce fully satiated animals ?
In normal conditions, high level of insuline is secreted because there is food in the pipeline so it might signal the brain to produce the sensation of satiety.
If we injected a large dose of insulin, the high insulin levels direct much of the blood glucose into the storage, resulting in hypoglycemia (reduced circulating glucose) which the brain detects via glucodetectors, leading to a hunger response.
What happen is we lesioned the ventromedial hypothalamus (VMH) ?
Because the VMH is the ‘‘satiety center’’, if we lesioned it, it will leads to hyperphagia (ate to excess) and then will eventually lead to obesity.
What happen is we lesioned the lateral hypothalamus (LH) ?
Because the LH is the ‘’ hunger center’’, if we lesioned it, it will leads to cessation of eating (aphagia) and then eventually leads to a weight loss.
What are the two behaviors that the VMH and LH can cause ?
Hyperphagia (VMH)
Aphagia (LH)
If there is a high level of insulin, what is the feeling that an animal will express ?
Satiety (appetite has been satisfied)
If there is a low level of insulin, what is the feeling that an animal will express ?
Hunger
What is the hormone that is released by fat cells ?
Leptin
Why the brain is monitoring the circulation of leptin in the body ?
Because leptin allows the brain to measure and regulate the body’s energy reserves in the form of fat.
What defects in leptin production or leptin sensitivity can cause ?
It causes a false underreporting of body fat and lead to overeating, especially of high-fat or sugary foods.
Which hormone is known to be a powerful appetite stimulant ?
Ghrelin
How does ghrelin is released in the blood ?
Ghrelin is released by endocrine cells in the stomach.
How is the level of ghrelin during fasting ?
High
*Ghrelin is an appetite stimulant, it plays an important role in both seeking and consuming foods
How is the level of ghrelin after a meal ?
Low
What happen with the level of ghrelin with obese people ?
Their level of ghrelin do not drop after a meal so the level of ghrelin is always high than leads to a continual hunger.
Which hormone is working in opposition to ghrelin ?
PYY 3-36
What is the role of PYY 3-36 ?
Provides a potent appetite-suppressing stimulus to the hypothalamus (Decrease food intake)
How is the level of PYY-3-36 before eating ?
Low
How is the level of PYY 3-36 after a meal ?
Rise rapidly (High)
What are the four types of biological rhythms and provide an example with each.
Ultradian (sleep cycle): shorter than a day
Circadian (activity): 24 hours period
Infradian (menstrual cycle): longer than a day
Circannual (breeding): Annual basis
True or false.
Enable animals to anticipate an event
and help with survival
True.
How long does the circadian rhythm lasts ?
About 24 hours
Can the circadian rhythm can be longer than 24 hours ?
Yes
Name examples of zeitgeber.
Any external cues such as light, food, etc.
What is a free-running period ?
Rhythm of behavior shown by an animal deprived of external cues.
Where does endogenous periods occurred ?
In the suprachiasmatic nucleus (SCN)
What happen to animals who have a SCN lesion ?
Circadian rhythms are disrupted. (Irregular rhythm)
What happen to hamsters with SCN lesions receiving SCN tissue transplant from hamsters with very short period ?
Circadian rhythms restored, nut matched rhythm of donor.
How is SCN informed about day and night ?
In mammals, light goes to SCN via retinohypothalamic pathway.
Retina ganglions cells are sensitive to light because they contain a special photopigment, called melanopsin.
Retina ganglions cells detect light with melanopsin and then release glutamate in the SCN. Glutamanergic synapses trigger a chain of events in SCN cells that, promotes the production of Per protein.
Can blind mices can detect light ?
Yes, because their intrinsically photosensitive retinal ganglion cells still function.
Why blue light has the largest effect on human circadian systems ?
Because melanopsin is most sensitive to light frequencies in the blue range.
Explain the whole system that allowed the SCN neurons to keep time.
Clock and Cycle (two proteins) bind together to form a dimer (a pair of molecules joined together).
They go to the nucleus and bind to DNA to promote the transcription of two other genes (Per and Cry).
Per and Cry bind together to form a dimer.
They inhibit expression of the Clock/Cycle genes that began the whole process.
With time, Per/Cry proteins either degrade or become chemically modified, eventually the inhibition is lifted, starting the whole cycle over again.
True or false.
Double Clock mutants
are severely arrhythmic
True.
When does the vertex spikes appear ?
During Stage 1
What are the four functions of sleep ?
Functions of sleep: • Energy conservation • Niche adaptation • Body restoration • Memory consolidation
What are the three effects of sleep deprivation ?
Effects of sleep deprivation - the partial or total prevention of sleep: • Increased irritability • Difficulty concentrating • Episodes of disorientation
What can happen in a case where someone is in total sleep deprivation ?
He can die.
Total sleep deprivation compromises the
immune system and leads to death.
What happen to a person who has a fatal familial insomnia disorder ?
The person sleeps normally at the beginning of their life but stop sleeping in midlife and die 7-24 months later
What happen to the brain of a person who has a fatal familial insomnia disorder ?
Autopsy shows degeneration in the brain
Is Glutamate is inhibitory or excitatory ?
Excitatory
Is GABA is inhibitory or excitatory ?
Inhibitory
If we transect the lower brain producing an isolated brain, what would happen ?
Signs of alternating between wakefulness, SWS and REM Sleep, showing that systems controlling sleep are found in the brain.
If we transect the brainstem at the midbrain producing an isolated forebrain, what would happen ?
Signs of a constant SWS, showing that a forebrain system promotes SWS and that brainstem systems promote wakefulness and REM sleep.
What is the disorder that involves frequent, intense episodes of sleep, which last from 5 to 30 minutes and can occur anytime during the usual waking hours ?
Narcolepsy
Name one thing that the subcoeruleus (a brain region that is associated with REM sleep) does regarding the muscles.
One job of the subcoeruleus is to profoundly inhibit motor neurons to keep them from firing.
Glutamatergic neurons in the subcoeruleus excite neurons in the ventral medulla, which in turn project axons down the spinal cord to release the inhibitory transmitters GABA and glycine to deeply inhibit spinal motor neurons.
What can also be associated with narcolepsy ?
Cataplexy, a sudden loss of muscle muscle tone, leading to collapse of the body without loss of consciousness. It can be triggered by an intense emotional stimuli like laughter and anger.
Which sleep phase people with suffering narcolepsy entering ?
REM sleep
Regarding neurons, what is the difference between normal people and people with narcolepsy ?
Narcoleptics have only 10% of their hypocretin neurons.
This degeneration of hypocretin neurons seems to cause inappropriate activation of the cataplexy pathway that is normally restricted to REM sleep.
Loss of those neurons in narcolepsy results in abrupt transitions, rather than orderly progression, through various sleep states.
What is the role of hypocretin neuron ?
Control our switching between wakefulness, NREM and REM sleep.
Name one region of the brain that is active during REM sleep.
The subcoeruleus nucleus
What happen to people with REM sleep behavior disorder ?
They lose normal muscle paralysis during REM sleep, which results in pathological levels of movements during REM sleep episodes.
What is the role of subcoeruleus cells in the sleep ?
SubC cells are glutamatergic (excitatory). So, they are thought to induce REM sleep muscle paralysis by recruiting GABA/glycine neurons in the ventromedial medulla (VMM) and spinal cord. Those GABA/glycine neurons will eventually lead to muscle atonia by inhibiting skeletal motoneurons
Which region of the brain is important in slow-wave sleep ?
Basal forebrain
Which region of the brain is important in arousal ?
Reticular formation
So, if we active the reticular formation, wakefulness
What is the process by which the initial decision is made for a fetus to develop as a male or a female ?
Sex determination
What is the main event of the sex determination ?
The fusion of egg and sperm
If sperm that enters the egg has a Y chromosome, is it a male or a female ?
Male
If sperm that enters the egg has a X chromosome, is it a male or a female ?
Female
What is the name of the developmental process of becoming male or female ?
Sex differentiation
What are gonads that have not yet been differentiated into testes or ovaries ?
Indifferent gonads
Which gene is important for the development of testes ?
SRY gene (Sex-determining Region on the Y chromosome)
What happen if there is no SRY gene ?
Without SRY gene, no Sry protein is made and an ovary forms
True or false.
Embryos don’t have early tissues for both male and female structures ?
False.
Embryos have early tissues for both male and female structures.
Developing testes produce several hormones or very little ?
Several hormones
Developing ovaries produce several hormones or very little ?
Very little
What are the two hormones from the testes masculinize the system ?
Testosterone and anti-mullerian hormone (AMH)
What testosterone does in the system ?
Promotes development of the wolffian system
What anti-mullerian hormone (AMH) does in the system ?
Cause regression of the mullerian system
What happens with the wolffian ducts and the mullerian system in males ?
In males, the wolffian ducts develop, the mullerian system shrinks
What happens with the wolffian system and the mullerian ducts in females ?
In females, the mullerian ducts develop, the wolffian system mostly degenerates
What is 5a-reductase ?
Enzyme in genital skin that converts testosterone into dihydrotestosterone (DHT), necessary to form male genitalia (penis and scrotum)
How does the testosterone is converted into dihydrotestosterone (DHT) ?
By the enzyme 5a-reductase
What happens in the absence of testes and their secretions ?
The wolffian ducts regrees and the mullerian system develops.
What is the wolffian ducts ?
A duct system in the embryo that will develop into male structures if testes are present (the epididymis, wa deferens, and seminal vesicles)
What is the mullerian ducts ?
A duct system in the embryo that will develop into femal reproductive structures if testes are not present (oviduct, uterus and inner vagina)
What is the anti-mullerian hormone (AMH) ?
A protein hormone secreted by the fetal testis that inhibits mullerian duct development
Regarding the external, what happen if genital skin is in presence of DHT ?
DHT induces skin to form scrotum: tubercle forms penis.
What happen to the mullerian ducts in absence of AMH ?
Mullerian ducts form oviducts, uterus and inner vagina
What happen to the wolffian ducts in absence of testosterone ?
The wolffian ducts will regress and no prostate or bulbourethral gland forms
What happen to skin in absence of DHT ?
Skin forms labia and outer vagina: tubercle forms clitoris
What happen in the subcoeruleus nucleus with patients in REM sleep behavior disorder (RBD) ?
The SubC pathway is not working properly in these individuals. As such, the motor neurons of RBD patients are not inhibited while they are in REM and thus, they are physically active during the REM phase of sleep. Remember, during this phase the body is typically paralyzed in non-RBD patients.
True or false.
The same testicular steroids that
masculinize the genitalia early in life not
masculinized the developing brain.
False.
The same testicular steroids that
masculinize the genitalia early in life also
masculinize the developing brain.
What is the organizational effect ?
Hormones permanently organize the nervous system during early development for adult sexual behaviors.
When does a hormone can have an organizational effect ?
During a specific sensitive period, generally in early development
What is an organizational hypothesis ?
A single unitary signal (androgen) diffuses through
all tissues, masculinizing body, brain,
behavior
Why does newborn female rats treated with estrogens also failed to show lordosis behavior in adulthood ?
Because estradiol is a principe metabolite of testosterone. In a single chemical reaction called aromatization, the enzyme aromatase converts testosterone to estradiol. So, testicular androgens enter the brain and are there converted into estrogens, and that these estrogens are what act on neurons to masculinize the developing rodent nervous system.
Explain the steps of the aromatization hypothesis.
- Testes release testosterone into the bloodstream
- Testosterone enters neurons in the brain
- Hypothalamic neurons produce the enzyme aromatase which will converts testosterone into an estrogens, estradiol.
- Estradiol will binds to estrogens receptor
- The estrogen-receptor complex binds DNA in the nucleus
- The estrogen-receptor complex will increase the transcription of some genes and will decrease the transcription of others. This altered gene expression prevents the appearance of feminine behaviors, such as lordosis, in adulthood. (depending on the cofactor, the effect can be different)
- Estrogen molecules in circulation are bound by a-fetoprotein (aFP). aFP prevents maternal estrogens from entering the brain, thereby, protection females from being masculinized by circulating estrogens.
What is sexual dimorphism ?
The condition in which males and females show pronounced sex differences in appearance.
True or false.
Sensitive period can vary depending on the species and the behavior.
True.
Where does investigators found a nucleus that has a much larger volume in males than females ?
In the preoptic area. (SDN-POA)
What happen to the size of the SDN-POA to males castrated at birth ?
They have much smaller SDN-POAs in adulthood.
What happen to the size of the SDN-POA to females androgenized at birth ?
They have much larger SDN-POA, male-like as adults.
What happen to the size of the SDN-POA to male castrated in adulthood ?
Did not alter the size of the SDN-POA.
Regarding mating behaviors, what happen to a male castrated in adulthood ?
He loses interest in mating because there is no testosterone production.
What treatment can restored briefly mating behavior ?
The activational effect
What is the purpose of emotions ?
Survival
Making life meaningful
Motivation
Decision making
What folk psychology is proposing ?
Feeling triggers autonomic reaction
- Stimulus
- Perception/Interpretation (danger)
3) Particular emotion experienced (fear)
4) Specific pattern of autonomic arousal (heart races, etc)
What James-Lange Theory is proposing ?
Autonomic reaction triggers feeling
- Stimulus
- Perception/Interpretation (danger)
3) Specific pattern of autonomic arousal (heart races, etc)
4) Particular emotion experienced (fear)
What Cannon-Bard theory is proposing ?
Simultaneous feeling and autonomic reaction
- Stimulus
2) Perception/Interpretation
3) General autonomic arousal (heart races, etc), and particular emotion experienced (fear)
How facial expressions are mediated ?
By muscles, cranial nerves and CNS.
What is the system is a set of structures in the brain that deal with emotions and memory and is composed of four main parts: the hypothalamus, the amygdala, the thalamus, and the hippocampus.
The limbic system
Which structure in the brain is a key in the mediation of fear ?
Amygdala
What is the pathway that bypasses conscious processing and allows for immediate emotional reactions to stimuli ?
Low road
What is the pathway bringing the incoming information through sensory cortex, is slower and integrated with higher-level cognitive processes ?
High road
Biologically, how can we know that we are experiencing stress ?
When homeostatic balance is upset
What is the initial response to stress ?
The alarm reaction
Which hormones act faster between epinephrine/norepinephrine and cortisol ?
Epinephrine/Norepinephrine
