235 homeostasis

what is homeostasis?

is the process by which the body achieves a stable, balanced
internal environment.

what is a ser zone?

range within which a physiological system can function

what is the set point?

which a given physiological system functions best

homeostasis works like a ?

thermostat, if the space is too cold, a thermostat will try to make it hotter and vice versa

what is negative feedback?

whatever is happening in a physiological system to cause it to deviate from the set point, homeostasis counteracts it by doing the opposite in order to find the set point again.

what is thermoregulation?

process by which the body maintains an ideal temperature

For mammals like you and me, body temperature is maintained

physiologically by utilizing the heat produced through

_______

metabolism

Reptiles have extremely low metabolisms, and thus produce ____ ______ _______

less heat internally.

preoptic area (POA) of the hypothalamus takes care of

the_______l responses that raise body temp in

response to cold, such as: 

physiological, shivering

what is shivering?

heat generated through metabolic burn required for motion

Constriction of blood vessels in the body’s exterior: 

reduced blood flow makes skin and fat more

effective as insulation

the lateral hypothalamus is crucial for the _____ regulation of

temperature, such as 

behavioral, as seeking out sources of heat, increasing the surface area of the body that

gets heat exposure (basking in the sun),

what are your two forms of thirst?

osmotic thirst and hypovolemic thirst

what is osmotic thirst?

• your body is filled with salt water – when fluid levels drop, salt concentrations in
  the fluid between your cells increase

• triggered by an upswing in salt levels via urination (the kidneys retain salts) or salt consumption

what is hypovolemic thirst?

• decrease in the volume of bodily fluids, such as blood (which, again, is mostly water).

this kind of thirst

• is triggered even if salt concentrations do not change (caused by sweating)

When the fluid around the osmosensory neurons is too salty,

they ______. When it is not salty enough, they ______. Other cells

have this property

shrink and swell

circumventricular organs contain ________ ________

that detect changes in the concentration of salt in the

cerebrospinal fluid of the ventricular system

osmosensory neurons

what is osmosis ?

diffusion of solvent molecules across a permeable biological membrane. Cellular

membranes throughout the body are semipermeable to water.

Changes in salt will cause cells to shrink or

expand via osmosis as water passes through

membranes to create _______ concentrations

inside and outside the cell 

equal 

Hypovolemic thirst: _______(pressure) in the the blood vessels of the kidney and the heart monitor changes in blood volume by detecting when the walls of the blood vessels stretch or contract

baroreceptors

what are nutrients?

chemicals required for the normal maintenance and function of the body

what are essential nutrients?

are those that the body cannot manufacture and must be obtained from diet.

what is the primary sugar that your body used for enegery?

glucose?

When glucose levels in the blood rise, the hormone insulin
allows

glucose to enter muscles and liver cells for use or to be
converted into glycogen for short-term storage

When glucose levels fall, glycogen is converted back into

glucose by the hormone glucagon

what is diabetes?

disease that results from a failure of insulin to allow

glucose to be taken into cells

what is type 1 diabetes?

juvenile-onset’ and occurs when the pancreas stops making insulin

what is type 2 diabetes?

adult-onset’ and occurs when cells no longer respond to insulin. Too much glucose in the blood
(hyperglycemia) can lead to, among other things, high blood pressure

the majority of energy is spent on ________, or

your level of energy use when you are at rest.

basal metabolism

The majority of energy is spent on basal metabolism, or

your level of energy use when you are at rest. This energy

goes to:

Heat production

Maintenance of ion gradients, especially in the brain

Life-sustaining cellular processes

what is metabolic adaptation?

Your basal metabolism will decrease when energy intake decreases

what is hunger?

the motivational drive to eat

what is satiety?

the feeling of being full

Hormones interact either directly or indirectly with the

hypothalamus to produce ______ and ______

hunger and satiety

signal satiety when they are activated and thus inhibit hunger and feeding

POMC neurons

signal hunger when they are activated and thus promote feeding

NPY neurons

neurons are named for the non-classical peptide neurotransmitter they use to communicate with their targets

NPY and POMC neurons

The ___________ of the hypothalamus monitors the levels of various hunger and satiety-relevant hormones, which can activate one of two different types of neurons in the arcuate: POMC and NPY neurons

arcuate nucleus

released from digestive organs in the absence of food in the gut. Ghrelin levels drop off after eating. High ghrelin levels activate NPY neurons and thus stimulate hunger

Ghrelin

as described previously, released from the pancreas in response to food. High insulin levels inhibit NPY neurons, reducing hunger. POMC neurons become disinhibited (activated) when NPY neurons turn off, increasing satiety

Insulin

 released from fat cells. The amount of circulating leptin is proportional to body fat levels, thus providing information about long-term energy reserves. High leptin both inhibits NPY neurons AND activates POMC neurons, reducing hunger and promoting satiety

Leptin

released from digestive organs in the presence of food in the gut. GLP-1 stimulates insulin release from the pancreas. It also activates POMC neurons

Glucagon-like peptide 1 (GLP-1)

________ is a GLP-1 receptor agonist. Marketed under the trade name Ozempic, it is a treatment for Type-II diabetes administered as a once-weekly injection. It is also being used as a weight-loss drug. It reduces appetite directly (by activating POMC neurons) and indirectly (via the effect of insulin on NPY cells)

Semaglutide

Marketed under the trade name Ozempic, it is a treatment for Type-II diabetes administered as a once-weekly injection. It is also being used as a weight-loss drug. It reduces appetite directly (by activating POMC neurons) and indirectly (via the effect of insulin on NPY cells)

Semaglutide!

The flavors that human beings find enjoyable (e.g. sweet) are highly correlated with the ___________.

caloric load of food

It seems clear that human beings will eat beyond our homeostatic needs simply because it’s ________. 

pleasurable

energy intake is also regulated by _____(pleasure-seeking) mechanisms

hedonic

When it comes to calories and nutrients, our bodies seem to be adapted to _____ not _____ (this is also why we are physiologically biased toward weight gain).

scarcity and abundance

Hedonic eating motivates us to take advantage of ______, _____resources (such as high calorie foods) whenever we have the opportunity to do so.

scarce, vital

The ________ (NAcc) is a part of the basal ganglia that is involved in motivation in both humans and rats

nucleus accumbens

Many neurons in the nucleus accumbens express the mu-opioid receptor, which is activated by ____________ neurotransmitters

endogenous opioid

Many neurons in the nucleus accumbens express the ______ receptor, which is activated by endogenous opioid neurotransmitters

mu-opioid

Injection of the mu-opioid receptor agonist DAMGO directly into the nucleus accumbens causes … 

rats to consume more sugar water even if the rat is neither hungry nor thirsty

Endogenous opioid signaling in the nucleus accumbens ensures …

that no opportunity to feed on highly caloric food is missed even if there is no homeostatic demand for energy

Refined and processed foods engineered to achieve a ______, the amount of an ingredient needed to make a food maximally delicious.

bliss point

In general, the more you eat of a specific food, the less you want it. However, even if you are relatively full, you may still be willing to consume a good amount of a very different food. For instance, you would probably refuse more savory food following your entrée, but you may be willing to have dessert

Sensory specific satiety