Physiological Homeostasis

What is the idea of hierarchy of importance in terms of homeostasis?

An example of the hierarchy of importance in homeostasis is a high salt intake. This increases [blank_start]osmolarity[blank_end] of the blood. Thus, more [blank_start]water[blank_end] moves into the blood. This balances osmolarity but increases [blank_start]plasma volume[blank_end]. Thus, MABP increases which causes [blank_start]hypertension[blank_end] in the long term. Whilst hypertension is undesirable for the body, the more immediate high osmolarity in the blood caused by excessive salt intake must be dealt with in this way.

What is the correct name of the mechanism in which: A variable is regulated about set point A change in that variable is compared against that point Deviation from that point leads to a response The response moves the variable back to the set point And turns the response off

[blank_start]Sensors[blank_end] - detect changes in the physiological variable [blank_start]Afferent pathway[blank_end] - carries signals from sensors to integrating centre [blank_start]Integrating centre[blank_end] - compares inputs from sensors against physiological set point and elicits a response [blank_start]Efferent pathway[blank_end] - carries signals from integrating centre to effectors [blank_start]Effector[blank_end] - produces a response to bring the physiological variable back to the set point

Which of these structures are examples of neuronal integrating centres in the brain?

In homeostatic negative feedback mechanisms, what must there be to allow fine-tuning of variables?

This diagram shows the two systems involved in thermoregulation. Label it.

This diagram shows the endocrine systems in the body. Label it.

All hypothalamic/pituitary hormones are peptides, polypeptides or glycoproteins

This diagram shows the endocrine hormone negative feedback arc controlling blood glucose. Label it.

What is a local homeostatic control mechanism?

One example of a local negative feedback mechanism is in skeletal muscle. When skeletal muscle is contracting at a fast rate, there is increased [blank_start]carbon dioxide[blank_end] and [blank_start]lactic acid[blank_end] concentration in the blood. This is sensed in the [blank_start]arterioles[blank_end] which stimulates them to [blank_start]dilate[blank_end]. This increases blood flow to the muscles. This removes [blank_start]carbon dioxide[blank_end] and [blank_start]lactic acid[blank_end] from the tissue and thus their concentrations return to normal.

What is the correct name of the mechanism in which: A change in a variable is anticipated A response to that change is brought about before that change is even actually detected

The fight or flight response is an example of a feed-forward control mechanism. When a threat is perceived, the [blank_start]sympathetic[blank_end] nervous system anticipates physical exertion whereby the individual will need to fight the threat or flee from it. The sympathetic nervous system activates the release of noradrenaline and [blank_start]adrenaline[blank_end] to increase heart [blank_start]rate[blank_end] and blood flow in the [blank_start]muscles[blank_end]. This prepares the body for increased [blank_start]oxygen[blank_end] demand.

Feed-forward mechanisms can be the result of learned behaviour. For example... 'Cues' can be associated with an incoming meal. Therefore, this cue will trigger anticipation of [blank_start]digestion[blank_end]. The [blank_start]parasympathetic[blank_end] nervous system stimulates the secretion of [blank_start]saliva[blank_end] and [blank_start]gastric juice[blank_end]. This prepares the body for digestion before food is even ingested.

What is the correct name of the mechanism in which: A change in a variable triggers a response That response furthers the change in that variable The variable is therefore amplified, not normalised

One example of a positive feedback mechanism is parturition. When the head of the foetus begins to push against the cervix, [blank_start]nerve impulses[blank_end] are transmitted to the brain. The [blank_start]pituitary[blank_end] gland is stimulated to secrete [blank_start]oxytocin[blank_end]. This is carried in the [blank_start]bloodstream[blank_end] to the uterus. It then stimulates uterine [blank_start]contractions[blank_end] which push the baby towards the cervix. Therefore, the [blank_start]pituitary gland[blank_end] will be stimulated even more so more [blank_start]oxytocin[blank_end] will be secreted. The mechanism is terminated when the baby is born.

Hormones are derived from steroids only

Select all the properties that apply to peptide/protein/glycoprotein hormones.

Select all the properties that apply to steroid and thyroid hormones