Body processes

Shivering – function, task and diseases

shivering

Medicine knows that shivering is a process of thermoregulation that attempts to compensate for heat losses through automatic muscle activity when there is a sharp drop in temperature . Shivering is triggered by the hypothalamus via the shivering pathways. Disorders of thermoregulation occur in diseases such as Sudeck’s disease .

What is the shivering?

Shivering is a thermoregulatory process designed to keep the human body at a good working temperature despite cold temperatures. Humans belong to the group of warm creatures and depend on the independence of their body temperature from the outside temperatures, since processes such as human metabolism depend on constant body temperatures. The greatest possible independence is made possible by thermoregulation.

In hot temperatures, for example, the human body automatically initiates sweating . In cold temperatures, it gains heat through processes such as shivering and the associated muscle activity. However, the net heat output from shivering is low when the body has poor insulation. For example, the muscles have to be supplied with more blood, which means that heat is lost in the beginning when you tremble .

The core temperature of the body only rises when the muscles involved are already warm. The involuntary tonic muscle activity of the cold shivering therefore only sets in when the temperature drops sharply and is only used by the body when there seems to be no other way out.

In warm-blooded animals, such as humans, the central dithering path leads from the higher-level control points of thermoregulation to the main areas of the motor system. Shivering is triggered and maintained via this trembling path.

function & task

Shivering is said to make people gain warmth. When the human body temperature drops due to high heat losses due to a low outside temperature, the main thermoregulatory switchboard in the hypothalamus reacts to this phenomenon by stimulating the anterior pituitary gland . This stimulation causes the anterior pituitary gland to release TRH , i.e. the thyrotropin-releasing hormone. This process causes the sympathetic tone to rise involuntarily. 

The increased sympathetic tone is reflected in various effector organs. The peripheral blood vessels react to the increased tone, for example, with vasoconstriction ( narrowing of the vessels ), which reduces heat loss via body surfaces. The hair stands up on the musculi arrectores pilorum, so that the skin pores close and secretory-related heat loss is reduced.

Brown adipose tissue responds to the increased sympathetic tone by producing heat in the form of increased lipolysis , and in the musculature, extrapyramidal efferents produce an increase in skeletal muscle tone that induces shivering and thus triggers increased heat release.

The simultaneous release of TRH is also essential for heat production. The hormone corresponds to a tripeptide with various effects. As a neurotransmitter and neuromodulator, the hormone acts internally in the hypothalamus and at the same time stimulates the increased secretion of TSH within the pituitary gland . TSH in turn stimulates thyroxine secretion in the thyroid gland .

In peripheral tissues , such as brown adipose tissue and skeletal muscles , this hormone is converted to triiodothyronine , which promotes heat generation in four different ways: the basal metabolic rate increases in the metabolism , the provision of energy in the muscles increases through increased gluconeogenesis in the liver , in the brown adipose tissue, shiver-free heat generation takes place on the basis of oxidative phosphorylation and the heart rate is increased by triiodothyronine.

Compared to the other processes of thermoregulation, shivering is rather uneconomical and has a correspondingly poorer heat balance than the shivering-free heat generation in brown adipose tissue.

Diseases & Ailments

The thermoregulation and thus also the shivering can be disturbed for various reasons. One of the most common reasons is iron deficiency , which affects women in particular and is often caused by high iron losses during menstruation or increased iron requirements due to pregnancy . 

In addition to disturbed thermoregulation, an iron deficiency is associated with unspecific symptoms such as a reduction in endurance, a general susceptibility to infections , increased tiredness or weakness . Increasing exhaustion , increased irritability , headaches and a lack of concentration are also frequent accompanying symptoms of iron deficiency. The same applies to hair loss .

In the case of iron deficiency anemia and the associated anemia, the hemoglobin , the hematocrit and the number of red blood cells decrease . Pronounced pallor , low blood pressure , loss of consciousness and sleep disturbances can be symptomatic of iron deficiency anemia, as can rapid breathing , increased heartbeat , nail changes, tongue papilla atrophy, swallowing disorders or even eating disorders such as pica syndrome .

Thermoregulation and shivering are not only disrupted by iron deficiency. Any disturbances can just as easily be related to diseases such as Sudeck’s disease. In this disease, despite the cold outside temperatures, there is, for example, increased sweating and dilation of the blood vessels, as they are actually carried out as part of the heat dissipation at high outside temperatures. The processes described for heat reduction are typical functions of heat regulation that affect the entire body. They ensure that the body temperature is maintained despite the heat. However, since these processes occur independently of heat in Sudeck’s disease, this activity pattern leads to a spontaneous unilateral reflex pattern, which significantly disrupts central thermoregulation.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.