Gland sweat

These glands may undergo atrophy and keratinizing squamous-cell metaplasia. 

Vitamin A deficiency is associated with faulty modeling of bone, with production of thick, cancellous bone instead of thinner, more compact bone. 

Often both taste and smell are impaired in vitamin-A-deficient individuals, undoubtedly a result of a keratinizing effect. Hearing also may be impaired. Vitamin A deficiency can interfere with erythropoiesis, which may be masked by abnormal losses of fluid. Nerve lesions, increased cerebrospinal fluid pressure, and hydrocephalus have been reported. 

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Swaits reactions Sweat glands Sweep flocculation Sweet basil Sweet basil oil Sweet chocolate Sweet crude oil Sweeteners... 

Antiperspirants. Aluminum chlorohydrate, widely used as an antiperspirant (32), came into usage in the early 1940s (2). The mechanism for antiperspirant activity is the formation of an obstmctive aluminum hydroxide plug within the sweat gland duct (17). When aluminum chlorohydrate at body temperature is simultaneously diluted with sweat and exposed to the higher pH on the skin, insoluble aluminum hydroxide rapidly forms. 

The guarded hot-plate method can be modified to perform dry and wet heat transfer testing (sweating skin model). Some plates contain simulated sweat glands and use a pumping mechanism to deUver water to the plate surface. Thermal comfort properties that can be deterrnined from this test are do, permeabihty index (/ ), and comfort limits. PermeabiUty index indicates moisture—heat permeabiUty through the fabric on a scale of 0 (completely impermeable) to 1 (completely permeable). This parameter indicates the effect of skin moisture on heat loss. Comfort limits are the predicted metaboHc activity levels that may be sustained while maintaining body thermal comfort in the test environment. 

Sweating, the other powerful heat loss mechanism actively regulated by the thermoregulatory center, is most developed in humans. With about 2,6 million sweat glands distributed over the skin and neurally controlled, sweat secretion can vary from 0 to 1 I7(h m ). The other, lesser, passive evaporative process of the skin is from the diffusion of water. The primary resistance to this flow is the stratum corneum or outermost 15 pm of the skin. The diffusion resistance of the skin is high in comparison to that of clothing and the boundary layer resistance and as a result makes water loss by diffusion fairly stable at about 500 grams/day. 

Anthropologic features of humans, their physical activities, ventilation capacities, and the state of their circulation all affect exposure to chemical compounds. Some of the physiological determinants of exposure will be dealt with below. Exercise typically increases cardiac output, facilitates circulation, increases the minute volume of ventilation, is associated with vasodilation of the skin circulation, and increases perspiration and secretory activity of the sweat glands. All of these changes tend to facilitate the absorption of chemicals through multiple routes. 

Heat rash A rash that appears as small red spots on hot, moist skin. The spots are inflamed sweat glands. 

Sweat glands Increased activity in localized areas Cholinergic ... 

Functional TRPVl is expressed in keratinocytes, hair follicles, sebocytes and sweat gland cells [151, 152]. In organ cultures, activation by capsaicin of... 

Miliaria An acute inflammation of the sweat glands, characterized by patches of small red papules and vesicles, brought on by excessive sweating... 

A middle layer, the dermis, corium, or cutis, which contains the hair follicles and the sebaceous and sweat glands... 

Release autonomic nervous system all postganglionic neurons of parasympathetic system some sympatheticpostganglionicneurons innervating sweat glands (alpha motor neurons innervating skeletal muscle)b adrenal medulla (20% of secretion) secretion)... 

Figure 9.2 Autonomic nerve pathways. All preganglionic neurons release acetylcholine (Ach), which binds to nicotinic receptors (N) on the postganglionic neurons. All postganglionic neurons in the parasympathetic system and some sympathetic postganglionic neurons innervating sweat glands release Ach that binds to muscarinic (M) receptors on the cells of the effector tissue. The remaining postganglionic neurons of the sympathetic system release norepinephrine (NE), which binds to alpha (a) or beta (P) receptors on cells of the effector tissue. The cells of the adrenal medulla, which are modified postganglionic neurons in the sympathetic system, release epinephrine (EPI) and NE into the circulation.

Urinary bladder Salivary glands Sweat glands... 

Gastrointestinal tract Urinary bladder Sweat glands Reproductive tract, male Uterus... 

Sweat glands Salivary glands Lacrimal glands Heart Pupils... 

Unfortunately, chickens have no sweat glands, so they cannot perspire. To dissipate any excess body heat during the warm summer months, they must pant just like a dog. Panting increases the amount of carbon dioxide exhaled, itself decreasing the concentration of CO2 in a chicken s blood. The smaller concentration [CO2 ] during the warm summer causes the reaction in Equation (4.60) to shift further toward the left-hand side than in the cooler winter, i.e. the amount of chalk formed decreases. The end result is a thinner eggshell. 

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