14- Temperature and Thirst Flashcards
What is homeostasis
Physiological systems at equilibrium by constantly adjusting to change
Imbalance in homeostasis creates
‘arousal’ that initiates action
What is negative feedback
A process whereby the effect produced by an action serves to diminish or terminate that action
What are the components of a homeostatic “system”
- System variable
- Set-point
- Sensor
- Effector system
What is a system variable
Variable controlled by systems (e.g., temp, hydration, nutrients)
What is a set-point
The desired level of a variable
What is a sensor
A mechanism for measuring the variable
What is an effector system
Behavioural /physiological mechanism(s) to change variable and restore homeostasis
What are the sensors for regulating body temperature
Cells in the Pre-Optic Area of the Hypothalamus sense brain temperature & we have thermal sensors throughout our periphery
Extracellular fluid consists mainly of
- Water
- Salts (particularly sodium chloride)
Microinjection of small amounts of NaCl into certain brain areas induces
Drinking
Changes in osmolarity are monitored by
Osmoreceptors in the OVLT
Loss of extracellular fluid (ECL) levels can induce
Thirst in the absence of osmotic (salt) changes
Thirst stimulus arises from which 2 systems that measure blood pressure
- In the kidneys
- In the heart
Hypovolemia causes the release of what
The enzyme renin from the kidneys
Renin converts a blood-borne molecule into what
Angiotensin
Angiotensin stimulates what
Pituitary and kidneys to release hormone to conserve water and salt
What do baroreceptors detect
- Stretch in the atria of heart
- Volume of return blood through veins
Information is sent from baroreceptors to
Nucleus of the solitary tract
Information is sent from nucleus of the solitary tract to
Median preoptic area
