OLFACTORY ORGAN

OLFACTORY ORGAN

Olfactory receptors placed in olfactory region of nasal cavity (in superior nasal meatus). Receptors (1st neuron) associated with epithelial supporting cells. The peripheral process of olfactory cells carry the olfactory cilia and the central process form 15-20 olfactory nerves (1st cranial nerve), which pass through the foramens in cribriform plate and reach the olfactory bulb. The axons of 2d neurons runs through the olfactory tract terminate in olfactory triangle and anterior perforating substance, where the bodies of the 3d neurons lie. Axons of the 3d neurons get the uncus and other part of limbic system, which is cortical olfactory analyser.

 

TASTE ORGAN

In man gustatory buds (2000 in number) are situated in mucous membrane of the tongue, palatine, pharynx, epiglottis. Most of gustatory buds localised in vallataefoliatae and fungiform papillae of the tongue. In front 2/3 part of tongue tasting impulses are perceived by fibres of chorda tympani (intermediate nerve), in back 1/3 portion of tongue – by glossopharyngeal nerve, in lingual root and epiglottis – by fibres of vagus nerve.

The central process of first neurons, that are situated in mouth cavity, pass in composition of VII, IX, X cranial nerves to tasting sensory nucleus that positioned in medulla oblongata – nucleus tractus solitarius. Axons of second neurons run to the thalamus, where the third neuron is situated. Axons of third neurons terminate in uncus (cortex of cerebrum), where is situated a cortical taste analyzer.

 

GENERAL COVER

Includes a skin and hypodermic stratum. Skin forms general bodies cover, which defends the organism from influence of external environment. It carries out regulation of warmly, metabolism, breathing, excretes the sweat and fat and is as depot of power resources. Skin is sensory organ and built from two layers:

  1. epidermis(superficial layer);
  2. dermis(deep layer, or proper skin), which consists of fibrous connective tissue, elastic and muscular fibers.

Blood and lymphatic capillaries, and terminal nervous bodies present in superior dermal layer. Lower stratum of dermis passes into hypodermic base where agglomeration of adipose cells is situated.

Skin color depends on pigment (melanin), which positioned in innermost layer of epidermis. Hair and nails derive from epidermis.

Hairs cover the skin (except palms, soles, transitional part of lips, head and preputium of penis, minor pudenda labia). Hair has a shaft and root. Last lies in deepness of skin and terminates by hair bulb, which provides growth of hair. Root of hair lies hair follicle where sebaceous gland opens and erector pili muscle attaches.

Nail is flattened elastic structures of a horny texture plate lying in connective tissue nail bed where it begins to growth. In nail there distinguish a nail root, nail body and free edge, which stick out form nail bed border, and also cover margin and lateral margin.

Skin Glands. Derivates of skin – sebaceous glands and sweat glands – are learned in histology course carefully.

Mammary gland is modified sweat gland, which lies on fascia of major pectoral muscle on level of the ІІІ-VІ ribs. Body of breasts consists of lobes of mammary gland, which contain 15-20 lobules of mammary gland, dissevered one from one by bands of connective tissue. The smallest lobules consist of a cluster of rounded alveoli, which open into the smallest branches of the lactiferous ducts; these ducts communicate by to form larger ducts, and these end in a single canal, corresponding with one of the chief subdivisions of the gland. They converge toward the areola, beneath which they form dilatations sinus, which serve as reservoirs for the milk, and, at the base of the papillæ. Lobes are disposed relatively to mammary nipple radially, and the mammary ducts open on the top of nipple. Mammary areola positioned round mammary nipple covered areolar tubercles where open areolar glands.

 

Hypodermic stratum contains nervous and venous plexus, lymphatic vessels and hypodermic adipose tissue, which carry out function of thermal isolation and depot of energetic reserve.

Also a soft connective tissue there is situated.Поділитися цим:

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AnnaR

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Коментарі: 0Публікації: 9Реєстрація: 09-02-2021

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