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Bio Psych > Exam 2 - > Flashcards

Exam 2 - Flashcards

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1
Q

What does it mean when there’s lots of solutes in the outside fluid, but little in the inside?

A

Hypertonic - A LOT of tonicity (solutes)

If the interstitial fluid is hypertonic, water will leave the cells to balance the tonicity between the intercellular and interstitial compartments which will shrink the cells.

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2
Q

What happens when a cell shrivels up due to hypertonicity?

A

Cells cannot function when they shrink.

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3
Q

At what point will we have a non-functioning cell?

A

When the interstitial fluid is hypertonic (too much solute) relative to the intercellular fluid.

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4
Q

What happens to a cell when it is hypotonic?

A

When an interstitial fluid is hypotonic, and doesn’t have as many solutes as INSIDE the cell, so the water moves from outside the cell INTO the cell to balance the tonicity… so the cell literally explodes.

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5
Q

Is Alzheimers disease related to hypertonicity or hypotonicity?

A

Hypotonic

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6
Q

How do the different fluid compartments work together?

A

Layers that border on each other

Changes in the tonicity of one compartment will have effects on the next compartment, etc

Solution C – intracellular fluid
B – Intrastitial fluid
A - Blood

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7
Q

What is Thirst?

A

Thirst is a feeling or motivational state we experience when fluid is lost from our body and we need to replenish it

Thus, THIRST is the signal that initiates the correctional mechanism (drinking)

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8
Q

What causes us to approach water?

A

The feeling of thirst initiates the behavior of DRINKING (correctional mechanism)

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9
Q

Where do we lose the most water out of all these if we don’t exercise:

Perspiration
Evaporation
Respiration

A

Respiration

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10
Q

How much water do we lose in a day?

A

2.5L or 8 cups.

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11
Q

What are the 2 types of thirst?

A
  1. Osmotic – pure water thirst; remedy for this thirst is pure water.

+Happens when there’s a decrease in the intracellular fluid (because it moved to a different compartment)

+Caused by increased tonicity of the interstitial fluid

+Too many solutes for the level of fluid
Water is pulled out of cells to balance the solution

  1. Hypovolemic – low vol. thirst

+Initiated when there’s a decrease in total fluid volume
>e.g., serious blood loss, vomiting, diarrhea

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12
Q

How does Osmotic thirst happen?

A

Starts with blood being too hypertonic

When we eat, we are thirsty, especially when eating salty food

Also happens because we are losing water with salts due to excessive perspiration or excessive urination

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13
Q

I am eating dry ass saltine crackers with extra salt. What is the tonicity of my blood?

A

Hypertonic - the salt increases the tonicity of my blood. The water is drawn out of the interstitial fluid from the intracellular fluid in attempts to balance the fluid between the 2 compartments… The water leave cells to regain isotonic state but leaves SOLUTES, and there is increased concentration of solutes in the interstitial compartment.

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14
Q

What do osmoreceptors detect?

Where is it located?

A

Osmoreceptors in the brain detect cell dehydration (hypertonicity).

Monitors movement of water

Located in the OVLT near the 3rd ventricle by the blood brain barrier- when blood is hypertonic, it’s instantly aware of that.

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15
Q

What affects osmoreceptor firing rates?

A

Osmoreceptors signal the decrease in intracellular fluid levels by shrinking - the smaller they are, the more they fire. Larger they are, the less they fire.

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16
Q

When the osmoreceptors begin firing at higher rates, they stimulate cells in the _____________ __________ cells to release anti-diuretic hormone (ADH).

A

Posterior pituitary cells to release anti-diuretic hormone (ADH).

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17
Q

What is anti-diuretic hormone? What releases this?

A

It serves as the bandaid - you’ve already lost intracellular water, so that is why the OVLT is firing, so that we can prevent losing more water. So you stop sweating and such.

The Posterior pituitary cells releases this hormone.

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18
Q

What does the osmoreceptors also communicate with?

A

It also communicate with the Lateral Hypothalamus to promote drinking behavior.

Then the Lateral Hypothalamus in turn communicates with the Zona Inserta, to drink water.
>maybe selected for in evolution when water was not as available

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19
Q

What are the connections and projections from the OVLT?

A

OVLT connects to Posterior Pituitary Cells to produce the ADH, also projects from OVLT to Medial preoptic nucleus in the Hypothalamus to the Zona Inserta.

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20
Q

What happens when we stimulate Zona Inserta in animals?

A

They look for water and drink it.

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21
Q

What happens when there’s damage to the Zona Inserta?

A

Dehydrate to death because they will not search for water. Not even when there’s cool clear water in front of them.

22
Q

At what percentage of total fluid loss is someone experiencing hypervolemic thirst?

What is this loss due to?

A

20%, due to loss of both water and salt in the interstitial fluid - from excessive blood loss, diarrhea, vomitting

23
Q

Being stranded in the ocean is especially torturous because…

A

We are probably experiencing hypervolemic thirst at this point, and we are craving salt and water.

24
Q

How is hypovolemic thirst detected?

Where are the detectors located?

A

What’s monitored is the volume of the circulatory system - so losing blood volume, losing blood pressure.

So baroreceptors (aka pressure receptors) are located in the kidneys and the heart.

25
Q

When the baroreceptors are stimulated, what is the bandaid?

Where does the baroreceptors send information to?

A

Osmotic and/or hypovolemic thirst stimulates baroreceptors which causes the posterior pituitary gland to release antidiuretic hormone (ADH).
ADH causes kidneys to
reduce urine and RELEASE renin.

Renin artificially constricts blood vessels to INCREASE blood pressure, it also conserves salts. This is the bandaid that we put on after we have already lost some blood.

The baroreceptors also sends information to the NST (nucleus of the solitary tract), which then sends the information to the medial preoptic nucleus, which then signals to the zona inserta, and initiates drinking behavior.

It uses the same pathways as the Osmoreceptors.

26
Q

What does renin convert?

A

Renin converts angiotensonigen into angiotensin II.

27
Q

What does angiotensin ll do?

A
  1. Angiotensin ll tells the adrenal system to release aldosterone
  2. Acts on the subfornical organ which signals to the median preoptic nucleus, similar to the OVLT.
28
Q

How does renin communicate with adrenal glands?

A

Renin tells the adrenal glands to produce aldosterone.

Aldosterone tells Kidneys to retain sodium.

29
Q

Where are the baroreceptors located?

A

Atria and vessels of the heart. They are basically stretch receptors which measure the volume of blood pressure - like osmoreceptors, they can go either way: the greater the stretch, the higher the rate of signalling; lower blood pressure means less stretch and lower signal rate.

30
Q

Which part of the brain when activated actually stimulates drinking behavior?

A

Hypothalamus… but really from the stimulation of the median preoptic nucleus… which then signals to other areas of the LH and Zona Inserta.

31
Q

What are all the ways we can stimulate the median preoptic nucleus?

A
  1. Angiotensin II
  2. Subfornical organ
  3. Atrial Bario
  4. Nucleus of the Solitary Tract
  5. Osmoreceptors
32
Q

What is the process of the initiation of drinking?

A

The SFO responds to angiotensin II.

The SFO, the nucleus of the solitary tract and the OVLT communicate with the median preoptic nucleus.

The median preoptic nucleus communicates with the lateral hypothalamus zona incerta.

The zona incerta initiates the motor aspects of drinking.

33
Q

What drives sex, thirst, hunger; etc?

A

Hormones!

34
Q

What is Hyponatremia? What’s the danger of this?

A

Interstitial fluids, reduced concentration of sodium levels and unable to sustain neural transmission.

Danger is heart failure - pacemakers will go off.

35
Q

You can ward off thirst by just swishing water in your mouth. What system allows this?

A

Satiety system: Receptors may be located in the mouth, throat and digestive tract.

36
Q

Overdrinking water during endurance events may result in both low sodium and low fluid levels. How does this relate to athletes?

A

This is why sports drinks typically contain more salt than other beverages

37
Q

What is polydipsia and what area of the brain legioned will cause this?

A

Lesions of the septal area (anterior/older part by genu of CC) produce overdrinking (polydipsia).

38
Q

What happens when you drink gatorade?

A

We have added more salt into our blood - this salt in our blood will pull water from the interstitial fluid, which will pull water from the intracellular fluid which is already dehydrated… and this sick process of thirst is self-perpetuating.

39
Q

When should you actually drink gatorade?

A

When you’re actually losing tons of salt from vomitting and diarreahing.

40
Q

What are the 4 components of a regulatory system?

A

-System variable, set point, detector, correctional mechanism.
>whatever’s being regulated

> optimal range of values system value should be in

> monitoring

> when out of range from set point, corr. Mech, initiated.

41
Q

What is the difference between negative feedback and a satiety mechanism?

A
  • The effect produced by the correctional mechanism stops the correctional mechanism.
  • Satiety- Instead of monitoring the system variable like negative feedback, It monitors how long a correctional mechanism has been active

> Neg feedback = what’s being monitored is the system variable

> Satiety mechanism = Monitors the activity of correctional mechanism.

42
Q

Where do we keep the water in our bodies?

A

In order from most to least:

Intracellular (in our cells)
Interstitial fluid ( bathing cells)
Blood
CSF

43
Q

What is tonicity? Why is it important?

A

Concentration of a solute in any given volume of water

> Hypertonic- too much solute (high tonicity)

> Hypotonic-too little solute (low tonicity)

Isotonic- Same solution in both compartments (ideal)

44
Q

What does tonicity determine?

A

It determines the process of osmosis, where the water will move.

45
Q

What happens when you eat a bag of potato chips?

A
  • The blood (the first fluid compartment) becomes more hypertonic.
  • It causes the next fluid compartment (Interstitial) to pull water out – this will then increase the solute in the compartment (interstitial)
  • Then it will make the intercellular hypertonic-

> It’s isonic to the solution b, but hypertonic to solution c.

46
Q

What is osmotic thirst?

How is osmotic thirst detected?

How does their rate of firing change?

A

It’s a thirst for pure water. It signals a decrease in the intracellular fluid.

Osmodetectors, in the blood side of the BBB in the anterior portion of the 3rd ventricle.

Their rate of firing is dependent on it’s size. The smaller they are, the rate of firing increases, the larger they are, the rate of firing decreases.

47
Q

What and Where are the baroreceptors?

What happens in the kidney when there’s a decrease in volume of fluid?

A

They are a pressure detector, measuring volume of circulatory system (blood).

Located in our heart (carotid arteries) and kidneys.

If baroreceptors in kidney signals a decrease in volume of fluid, it starts producing Renin.

Renin converts angiotensonigen into angiotenson 2, which helps to constrict blood vessels. This is the band-aid from keeping the heart from pumping too much.

Angiotenson 2 also helps with volumetric thirst (lost volume)

Renin also tells the kidneys to conserve salts.

48
Q

What is the function of angiotenson? What is it converted from?

A

Renin converts angiotensonigen into angiotenson 2, which helps to constrict blood vessels. This is the band-aid from keeping the heart from pumping too much.

Angiotenson 2 also helps with volumetric thirst (lost volume)

49
Q

On what part of the brain do both osmotic signals (from osmoreceptors) and hypovolemic (baroreceptors) signals converge?

A

Median preotic nucleus in the hypothalamus, then signals are sent to lateral hypothalamus and the zona inserta.

> signals to seek out water and salts

50
Q

What is hyponatremia?

A

Heart arrhythmia occurs due to dangerously low levels of sodium due to overdrinking, blood loss, and oversweating.

Bio Psych (9 decks)

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