Thermoregulation (Karius) Flashcards
What parts of the body change temperature the most rapidly?
Feet, then hands, then skin
About how much does the core temperature change throughout the day?
1-2 degrees
Lowest at 6 am
What measures core temperature & the temperature around us?
Thermal Receptors
What are the cutaneous thermoreceptors most sensitive to?
Cold (10x as much as warm)
What information do the visceral thermoreceptors transmit?
Threats from ingested food that may change body temperature => hypothalamus
- Example: ice cream (causes brain freeze which would decrease blood temp. of brain)
Where are the thermoreceptors of the brain located?
Pre-optic and superoptic region of hypothalamus
What are the thermoreceptors in the brain most sensitive to?
Heat (3x as much as cold)
What structure determines the set body temperature, receives info about current temperature and decides what to do?
Hypothalamus
What happens to the core temperature when you sleep and exercise?
- Sleep: T decreases b/c set point decreases
- Exercise: T increases b/c set point increases
What receptors determine the core temperature of the body
Visceral and hypothalamic (preoptic & superoptic) thermal receptors
What does the posterior region of hypothalamus respond to?
Responds to cold by activating heat producing behavior
What does the anterior region of the hypothalamus respond to?
Responds to heat by activating heat loss behaviors
Why do babies need more adipose tissue?
Babies have higher surface area in proportion to size and will lose heat faster than adults
What systems can be used to produce heat
- Autonomic nervous system (esp. sympathetic)
- Endocrine
- Thyroxine
- Epinephrine
- Muscular activity
- Voluntary
- Involuntary (shivering)
- Non-shivering thermogenesis
- increase in metabolism
What part of the hypothalamus is responsible for shivering?
How does it do this?
Dorsomedial posterior hypothalamus => increase motor neuron excitation
You are cold and trying to produce heat
What division of the autonomic nervous system is involved in heat production?
Sympathetic Nervous System
In non-shivering thermogenesis, what hormone is released in response to cold?
Thyroxin-Releasing hormone => Thyroxin
Epinephrine
What activates hydrolysis of ATP in brown fat?
Sympathetic fibers & circulating Epinephrine
How is Brown Adipose Tissue used to produce heat
Hydrolysis of ATP via uncoupling proteins leads to heat production
What are the two kids of evaporative heat loss?
Insensible (respiratory)
Sweating (controlled)
What is convection?
Movement of molecules away from contact
Air Heating and Rising
What is conduction?
Transfer of heat between objects in physical contact with one another
heat from body dissipating to chair
What is radiation?
Transfer of heat between 2 objects that are not in physical contact
What is the innervation to the sweat glands?
Activated by what NT & what receptor does it bind?
Sympathetic cholinergic innervation
NT: Acetylcholine - binds mAChR
If there is a low flow rate of sweat, what is the sodium concentration in sweat?
High (couldn’t follow water)
If there is a high flow rate of sweating, what is the sodium concentration?
Low (no time to reabsorb water)
What happens to the body when there is a fever?
Set Point increases and will be greater than body temperature
- Endotoxins and Prostaglandin released
Explain the following characteristics of a Fever
- Core Temp
- Set Point
- Active Thermoregulatory response
- Signs present
- Subjective perception
- Cause
- Increased
- Increases
- Heat production
- Pallor, shivering, behavioral changes associated with being cold
- Subjectively cold
- Infectious agents producing inflammatory mediators acting in brain
Explain the following characteristics of Hyperthermia
- Core Temp
- Set Point
- Active Thermoregulatory response
- Signs present
- Subjective perception
- Cause
- Increased
- Normal
- Heat loss
- Flushes skin, sweating, behavioral changes associated with being hot
- Patient describes as being hot
- Increased heat production or decreased ability to eliminate heat (dehydration)
How does the hypothalamus regulate the autonomic nervous system for thermoregulation
- Dorsal longitudinal fasiculus (MAJOR)
- Medial forebrain bundle
- Mammillotegmental tract
What is the major hypothalamic nucleus associated with autonomic control of temperature
Paraventricular nuclei via dorsal longitudinal fasciculus (DLF)
Where does the dorsal longitudinal fasciculus send it’s axons
Dorsal motor nucleus of the vagus
Nucleus ambgiguous
Parasympathetic and sympathetic neurons in spinal cord
