Hunger and Thirst

Question 1

Anti diuretic Hormone

Answer 1

Enables the kidneys to reabsorb water from urine making urine more concentrated. Aka : ADH. It is an example of a vasopressin hormone. It is also secreted during sleep to preserve water at a time when you can’t drink. It helps you get through the night without peeing.

Question 2

Lateral preoptic area

Answer 2

Controls drinking: body monitors swallowing and stomach dissension so you don,t drink too much. It is an area to which the receptors relay their info.

Question 3

Osmotic pressure

Answer 3

The tendency of water to flow across a semipermeable membrane from an area of low solute concentration to area of high concentration. Occurs when salutes are more concentrated on one side of the membrane than the other.

Question 4

Semipermeable

Answer 4

Something is considered a semipermeable membrane when water can pass through but not salutes. (Membrane around cells is semipermeable)

Question 5

Osmotic thirst

Answer 5

A drive for water that helps restore the normal state. It is triggered when neurons detect their own loss of water.
Fun fact: rats with slow osmotic thirst show less anxiety and reaction to stress and increased sociability to the unfamiliar.

Question 6

OVLT - organum vasculosum laminae terminal is

Answer 6

Receptor around the 3rd ventricle in the brain that helps detect osmotic pressure. This receptor also receives input from digestive tract allowing it to anticipate osmotic need before body feels it.

Question 7

Paraventricular nucleus (PVN)

Answer 7

Part of hypothalamus that receives info from the receptors. Controls rate at which pituitary release vasopressin. Works same as supraotic nucleus.

Question 8

Subfornical organ (SFO)

Answer 8

Receptor that detects osmotic pressure and sodium content of blood. Works with OVLT receptor. Also found in 3rd ventricle of the brain.
Fun fact: blood brain barrier is weak in this area

Question 9

Supraoptic nucleus

Answer 9

Area to which the receptors (OVLT and SFO) relay information to this part of hypothalamus (along with PVN). These control the rate at which the posterior pituitary release vasopressin.

Question 10

Vasopressin

Answer 10

Hormone that raises blood pressure by constricting blood vessels. This helps compensate for decreased blood volume due to reduced water intake. It is an ADH

Question 11

Baroreceptor

Answer 11

One of the mechanisms for hypovolemic thirst. Pressure receptors for large veins to the heart.

Question 12

Name mechanisms for hypovolemic thirst

Answer 12

*baroreceptors
*signals to hypothalamus (vasopressin release)
*hormone release from kidneys and adrenals
* angiotensin II (indicates low blood pressure)
* aldosterone ( indicates low sodium)
Both together increase preference for saltiness

Question 13

Would adding salt to body’s extra cellular fluids increase or decrease osmotic thirst?

Answer 13

Adding salt to extracellular fluids would increase osmotic thirst because it would draw water from cells into extracellular space.

Question 14

Angiotensin II

Answer 14

A hormone that contracts blood vessels, released by kidneys to compensate for drop in blood pressure.
Low blood vol>kidneys release renin into blood>proteins in blood form angiotensin I>angiotensin I is converted to angiotensin II>A II contracts blood vessels and stimulates cells in Subfornical organ to increase drinking

Question 15

Hypovolemic thirst

Answer 15

A thirst that is triggered to restore lost salts(not just lost water). Thirst based on low volume.
Fun fact: An animal with osmotic thirst needs (pure) water whereas one with hypovolemic thirst cannot drink much pure water because it would dilute body fluids and lower solute concentration in blood . Animals have increased preference for salty water.

Question 16

Who would drink more pure water someone with osmotic thirst or hypovolemic thirst?

Answer 16

Someone with osmotic thirst would drink more water. Someone with hypovolemic thirst would drink more of a solution containing salts. People who have lost fluid from sickness/sweat would have more hypovolemic thirst.

Question 17

Sodium specific hunger

Answer 17

When an animal becomes deficient in sodium and shows an immediate strong preference for salty tastes.depends partially on hormones (aldosterone and angiotensin II) to change properties of taste receptors on the tongue to increase salt intake. It is one mechanism of hypovolemic thirst.

Question 18

Aldosterone

Answer 18

Hormone produced by adrenal glands that causes kidneys, salivary glands and sweat glands to retain salt. Indicator of low sodium. Together with angiotensin II change tad the receptors on tongue and in taste system to increase salt intake. Increases salt.