Phys 74 Flashcards

A nude hiker in dry air can maintain core temperature at ambient:
A. 20°F to 80°F
B. 35°F to 105°F
C. 45°F to 115°F
D. 55°F to 130°F

During exposure to cold wind, which temperature changes most?
A. Core temperature mostly
B. Skin temperature mostly
C. Brain temperature mostly
D. Muscle temperature mostly

Heat production is primarily a by-product of:
A. Conduction
B. Radiation
C. Metabolism
D. Evaporation

Total heat loss rate depends mainly on:
A. Sweat rate and shivering
B. Core→skin conduction, skin transfer
C. Skin melanin and hair density
D. Lung ventilation and urine flow

Subcutaneous fat reduces heat loss mainly by acting as:
A. Heat radiator
B. Active heater
C. Sweat reservoir
D. Heat insulator

Fat is an effective insulator because it conducts heat:
A. One third as readily
B. Twice as readily
C. Equal to muscle
D. Ten times less

In fingers and ears, arterial blood can enter venous plexus via:
A. Capillary loops
B. Lymphatic shunts
C. Arteriovenous anastomoses
D. Venules with valves

Skin serves as a controlled “radiator” mainly through:
A. Melanin production changes
B. Sweat duct remodeling
C. Muscle thermogenesis shifts
D. Blood flow to skin

Heat delivery to skin by blood is controlled chiefly by:
A. Arteriolar and AV constriction
B. Venous valve contraction
C. Capillary basement thickening
D. Lymphatic drainage increase

At room temperature, ~60% of heat loss occurs via:
A. Conduction to chair
B. Conduction to air
C. Radiation
D. Evaporation

Normally, direct conduction to solid objects accounts for about:
A. 3%
B. 10%
C. 25%
D. 60%

Under normal conditions, conduction to air accounts for about:
A. 3%
B. 60%
C. 5%
D. 15%

Even without sweating, insensible water loss is about:
A. 100–200 mL/day
B. 300–400 mL/day
C. 600–700 mL/day
D. 1200–1400 mL/day

Heat exposure triggers sweating via stimulation of the:
A. Posterior hypothalamus
B. Ventromedial hypothalamus
C. Mammillary bodies
D. Anterior preoptic hypothalamus

Sweating commands travel from hypothalamus mainly through:
A. Parasympathetic cranial outflow
B. Sympathetic outflow to skin
C. Somatic motor neurons only
D. Sensory afferent fibers

Sweat glands are innervated by sympathetic fibers that are:
A. Adrenergic only
B. Dopaminergic
C. Cholinergic
D. Peptidergic

The neurotransmitter released at sweat glands is:
A. Acetylcholine
B. Norepinephrine
C. Dopamine
D. Epinephrine

A sweat gland’s secretory portion is best described as:
A. Straight superficial tube
B. Flat epidermal sac
C. Branched acinar gland
D. Deep subdermal coiled tubule

Sweat reaches skin surface through the:
A. Secretory coil
B. Venous plexus
C. Duct through dermis/epidermis
D. Arteriovenous anastomosis

Heat loss from core to skin is limited most by:
A. Core-to-skin conduction rate
B. Glucose oxidation rate
C. Pulmonary diffusion rate
D. Renal filtration rate

Heat transfer from skin to surroundings occurs by all EXCEPT:
A. Radiation
B. Conduction
C. Metabolism
D. Evaporation

A patient with strong cutaneous vasoconstriction will have:
A. Increased core→skin heat conduction
B. Increased insensible evaporation
C. Increased radiant reflection
D. Reduced heat delivery to skin

With slight sweat stimulation, Na⁺ and Cl⁻ are:
A. Secreted rapidly
B. Excreted unchanged
C. Reabsorbed in duct
D. Concentrated in duct

At low sweating rates, urea/lactate/K⁺ are:
A. Very dilute
B. Rapidly reabsorbed
C. Essentially absent
D. Highly concentrated

Core temperature regulation relies mainly on:
A. Hormonal set points
B. Hypothalamic feedback control
C. Skin-only reflexes
D. Liver metabolic sensors

The main “heat center” region is:
A. Anterior hypothalamic-preoptic area
B. Posterior hypothalamic area
C. Cerebellar vermis
D. Medullary respiratory center

In the preoptic area, cold-sensitive neurons are:
A. Equal to heat neurons
B. Twice as many
C. About one third as many
D. Nearly absent

Heat-sensitive neuron firing with +10°C increases:
A. 10- to 20-fold
B. 2- to 10-fold
C. 0.5- to 2-fold
D. No significant change

The preoptic area can function as a:
A. Pain integration center
B. Respiratory rhythm generator
C. Plasma osmometer center
D. Thermostatic control center

TRP thermal sensors are a family of:
A. Cation channels
B. Chloride channels
C. Sodium pumps
D. G-protein receptors

TRP thermal channels are found mainly in:
A. Hepatocytes and pancreas
B. Somatosensory neurons, epidermal cells
C. Renal tubules only
D. Myocardial Purkinje cells

Whole-body skin chilling immediately increases:
A. Sweating rate
B. Skin vasodilation
C. Shivering heat production
D. Heat loss by radiation

If sweating is occurring, chilling will:
A. Intensify sweating
B. Replace sweating with panting
C. Increase duct secretion
D. Inhibit sweating

Chilling reduces heat loss primarily by:
A. Increasing skin permeability
B. Promoting skin vasoconstriction
C. Activating sweat gland ducts
D. Increasing evaporative cooling

Deep temperature receptors are found mainly in:
A. Spinal cord
B. Cerebral cortex
C. Cerebellum
D. Retina

Deep temperature receptors also exist in/around:
A. Lungs only
B. Lower limb veins
C. Cerebral ventricles
D. Great veins upper abdomen/thorax

Preoptic temperature signals are transmitted to the:
A. Cerebellar cortex
B. Basal ganglia
C. Posterior hypothalamus
D. Pineal gland

First major heat-loss response to overheating is:
A. Skin vasodilation
B. Piloerection
C. Shivering
D. Thyroxine release

Skin vasodilation during overheating occurs via:
A. Increased adrenal epinephrine
B. Increased posterior sympathetic drive
C. Increased vagal efferents
D. Inhibition of posterior sympathetic centers

The second major heat-loss mechanism is:
A. Piloerection
B. Shivering
C. Sweating
D. Thyroxine release

The third major heat-loss response is decreased:
A. Skin blood flow
B. Heat production
C. Radiation to air
D. Venous return

Decreased heat production occurs by inhibiting:
A. Shivering and chemical thermogenesis
B. Sweat duct reabsorption
C. TRP channel opening
D. Na⁺/K⁺ ATPase activity

When the body is too cold, the first response is:
A. Sweating
B. Skin vasodilation
C. Skin vasoconstriction
D. Decreased sympathetic outflow

Cold-induced vasoconstriction is caused by:
A. Inhibited posterior sympathetic centers
B. Stimulated posterior sympathetic centers
C. Increased parasympathetic tone
D. TRP channel blockade

Piloerection refers to:
A. Sweating onset
B. Shivering bursts
C. Vasomotor waves
D. Hairs standing on end

Piloerection is produced by contraction of:
A. Arrector pili muscles
B. Ciliary smooth muscle
C. Iris circular muscle
D. Sweat gland ducts

Increased thermogenesis in cold occurs via:
A. Sweating, vasodilation
B. Shivering inhibition, cooling
C. Shivering, SNS, thyroxine
D. Radiation, conduction

The primary shivering motor center lies in:
A. Ventral anterior hypothalamus
B. Dorsomedial posterior hypothalamus
C. Lateral preoptic cortex
D. Dorsal medulla

Rapid catecholamine-driven metabolic heat is called:
A. Shivering thermogenesis
B. Evaporative cooling
C. Chemical thermogenesis
D. Radiant heat loss

Chemical thermogenesis magnitude is proportional to:
A. Brown fat amount
B. Skin thickness
C. Sweating rate
D. Core blood volume

Mitochondrial uncoupling protein is also called:
A. Tropomyosin
B. Calmodulin
C. Hemoglobin
D. Thermogenin

Brown fat thermogenesis is triggered mainly by:
A. Parasympathetic acetylcholine
B. Sympathetic norepinephrine
C. Somatic motor firing
D. Cortisol release

Cooling the anterior preoptic area increases:
A. Cortisol secretion
B. ADH release
C. TRH production
D. Insulin release

Thyroxine increases chemical thermogenesis mainly by:
A. Raising cellular metabolism
B. Increasing skin sweating
C. Decreasing blood viscosity
D. Reducing mitochondrial number

Temperature control “feedback gain” equals:
A. ΔCore/ΔEnv minus 1
B. ΔEnv/ΔCore minus 1
C. ΔEnv × ΔCore minus 1
D. ΔCore × ΔEnv minus 1

Neck spinal transection above sympathetic outflow impairs:
A. GI motility control
B. Pupillary reflexes
C. Skin blood flow, sweating control
D. Renal autoregulation control

Substances raising hypothalamic set point are:
A. Antipyretics
B. Kinins
C. Bradykinins
D. Pyrogens

Pyrogens commonly arise from:
A. Bacteria and degenerating tissues
B. Normal muscle activity
C. Excess skin sweating
D. Low ambient humidity

Direct hypothalamic pyrogens immediately:
A. Lower set point
B. Raise set point
C. Stop sweating
D. Induce vasodilation

Bacterial products are phagocytized mainly by:
A. Neurons and astrocytes
B. Platelets and erythrocytes
C. Hepatocytes and myocytes
D. Leukocytes, macrophages, NK cells

“Leukocyte pyrogen” is also called:
A. TNF-alpha
B. IL-6
C. IL-1
D. Histamine

IL-1 causes fever primarily by inducing:
A. Leukotriene B4
B. Prostaglandin E2
C. Nitric oxide
D. Bradykinin

Blocking prostaglandin formation will:
A. Reduce or abolish fever
B. Increase fever duration
C. Prevent shivering only
D. Trigger sweating only

Prolonged high temperature can result from:
A. Pituitary adenoma
B. Stroke in cerebellum
C. Hypothalamic compression by tumor
D. Spinal cord demyelination

Heatstroke symptoms are worsened by:
A. Respiratory alkalosis
B. Leukopenia
C. Metabolic alkalosis
D. Circulatory shock from sweating

Hyperpyrexia fatal pathology includes:
A. Pulmonary edema, parenchymal degeneration
B. Renal infarcts, parenchymal degeneration
C. Hemorrhages, parenchymal degeneration
D. Bone marrow hyperplasia

Artificial cooling is used during:
A. Bronchoscopy procedures
B. Heart surgery to stop heart
C. Colonoscopy procedures
D. Cataract surgery cases

“Nonshivering thermogenesis” equals:
A. Shivering thermogenesis
B. Radiant heat loss
C. Chemical thermogenesis
D. Behavioral heat seeking

Sympathetic stimulation raises metabolism mainly via:
A. Norepinephrine and epinephrine
B. Acetylcholine and histamine
C. Dopamine and serotonin
D. GABA and glycine

Brown fat heat production rises because UCP:
A. Raises ATP synthesis
B. Uncouples oxidative phosphorylation
C. Blocks glycolysis enzymes
D. Stops electron transport chain

Infant brown fat is found mainly in:
A. Abdominal mesentery
B. Popliteal fossa
C. Facial subcutaneous tissue
D. Interscapular space

Cooling preoptic area increases TRH, leading to:
A. Increased thyroxine release
B. Decreased thyroxine release
C. Increased insulin release
D. Decreased cortisol release

Thyroxine increases thermogenesis by:
A. Increasing sweat salt loss
B. Reducing skin blood flow
C. Increasing cellular metabolic rate
D. Blocking shivering motor output

Poor thermoregulation after neck transection occurs because:
A. Skin blood flow increases
B. Hypothalamus loses sweat control
C. Adrenal medulla stops secreting
D. Skin temperature equals core

A classic bacterial pyrogen example is:
A. Myosin fragments
B. Collagen peptides
C. Lipopolysaccharide endotoxin
D. Serum albumin

Aspirin reduces fever mainly by:
A. Blocking TRH secretion
B. Inhibiting prostaglandin synthesis
C. Increasing brown fat amount
D. Activating shivering center

Hypothalamic compression causing hyperthermia is due to:
A. Brain tumor pressure
B. Viral myocarditis
C. Renal tubular necrosis
D. Peripheral neuropathy

Sudden set point increases can be triggered by:
A. Hypoglycemia only
B. Hypercalcemia only
C. Dehydration, pyrogens, tissue damage
D. Hyperventilation only

Hyperpyrexia damages tissues especially in the:
A. Skin
B. Brain
C. Spleen
D. Thyroid

Slight sweat stimulation causes low NaCl because duct:
A. Stops secreting precursor fluid
B. Actively secretes chloride outward
C. Increases sweat gland diameter
D. Near-complete NaCl reabsorption

At low sweating rates, urea/lactate/K become concentrated because:
A. Water reabsorbed, solutes retained
B. Solutes reabsorbed, water lost
C. Duct secretes extra potassium
D. Precursor fluid lacks electrolytes

Deep temperature receptors are also found in:
A. Retina and optic nerve
B. Cerebellar cortex
C. Abdominal viscera
D. Distal skin only

Preoptic temperature signals are relayed into the:
A. Anterior pituitary gland
B. Posterior hypothalamus
C. Basal ganglia circuits
D. Medullary pyramids

Shivering center is normally inhibited by:
A. Cold skin receptors
B. Posterior hypothalamic centers
C. Spinal cord thermoreceptors
D. Anterior preoptic heat center

Chemical thermogenesis increases metabolism via:
A. Sympathetic stimulation or catecholamines
B. Parasympathetic cholinergic firing
C. Cortical motor pathway discharge
D. Local sweat gland activation

Poor thermoregulation after neck transection occurs because hypothalamus can’t control:
A. Renal filtration and urine output
B. GI secretion and absorption
C. Pupillary light reflexes
D. Skin blood flow and sweating