Biomaterial Database

Human autonomic responses to actual and simulated weightlessness. 1991

D L Eckberg, and J M Fritsch

Department of Medicine, Hunter Holmes McGuire Department of Veterans Affairs Medical Center, Richmond, VA 23249.

Orthostatic dysfunction occurs after exposure to microgravity, and is not completely understood. The authors developed a device for stimulating carotid baroreceptors to test the hypothesis that exposure to microgravity leads to impairment of arterial baroreflex mechanisms. Data obtained before and after two head-down bedrest studies and before and after brief Space Shuttle missions indicate that baroreceptor-cardiac reflex control is impaired by simulated or actual weightlessness. The authors speculate that arterial baroreflex derangements combine with blood volume reductions and increased venous compliance to provoke orthostatic hypotension after microgravity exposure. Altered baroreflex function after missions may result from autonomic neuronal plasticity that develops during missions secondary to changes of cardiopulmonary and arterial dimensions and consequent changes of autonomic sensory input profiles.

UI	MeSH Term	Description	Entries
D011311	Pressoreceptors	Receptors in the vascular system, particularly the aorta and carotid sinus, which are sensitive to stretch of the vessel walls.	Baroreceptors,Receptors, Stretch, Arterial,Receptors, Stretch, Vascular,Stretch Receptors, Arterial,Stretch Receptors, Vascular,Arterial Stretch Receptor,Arterial Stretch Receptors,Baroreceptor,Pressoreceptor,Receptor, Arterial Stretch,Receptor, Vascular Stretch,Receptors, Arterial Stretch,Receptors, Vascular Stretch,Stretch Receptor, Arterial,Stretch Receptor, Vascular,Vascular Stretch Receptor,Vascular Stretch Receptors
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001341	Autonomic Nervous System	The ENTERIC NERVOUS SYSTEM; PARASYMPATHETIC NERVOUS SYSTEM; and SYMPATHETIC NERVOUS SYSTEM taken together. Generally speaking, the autonomic nervous system regulates the internal environment during both peaceful activity and physical or emotional stress. Autonomic activity is controlled and integrated by the CENTRAL NERVOUS SYSTEM, especially the HYPOTHALAMUS and the SOLITARY NUCLEUS, which receive information relayed from VISCERAL AFFERENTS.	Vegetative Nervous System,Visceral Nervous System,Autonomic Nervous Systems,Nervous System, Autonomic,Nervous System, Vegetative,Nervous System, Visceral,Nervous Systems, Autonomic,Nervous Systems, Vegetative,Nervous Systems, Visceral,System, Autonomic Nervous,System, Vegetative Nervous,System, Visceral Nervous,Systems, Autonomic Nervous,Systems, Vegetative Nervous,Systems, Visceral Nervous,Vegetative Nervous Systems,Visceral Nervous Systems
D014893	Weightlessness	Condition in which no acceleration, whether due to gravity or any other force, can be detected by an observer within a system. It also means the absence of weight or the absence of the force of gravity acting on a body. Microgravity, gravitational force between 0 and 10 -6 g, is included here. (From NASA Thesaurus, 1988)	Microgravity,Zero Gravity,Gravity, Zero