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Glandular endocrine system

Glandular endocrine system consists of glands with concentrated individual endocrine cells. Endocrine glands (endocrine gland) are the organs that produce and secrete specific substances directly into their blood or lymph. These substances are hormones - chemical controls necessary for life. Endocrine glands may be as autonomous bodies and epithelial derivatives (border) tissues. To the endocrine glands include cancer

Hypothalamic-pituitary system

Hypothalamus and pituitary are secretory cells, and the hypothalamus is considered an important element of the "hypothalamic-pituitary system."

One of the major glands of the body is the pituitary gland, which controls the operation of the majority of the endocrine glands. Pituitary gland - a small, weighing less than one gram, but very important for the life of the iron. It is located in a recess in the base of the brain and has three lobes - the front (glandular, or adenohypophysis), medium (developed it less than others) and rear (nervous share). Most important functions performed by the pituitary gland in the body can be compared with the role of the conductor of the orchestra, which sticks with light strokes indicates when one or the other instrument should come into play. The pituitary gland produces hormones that stimulate the work of almost all the other endocrine glands.

The anterior lobe of the pituitary gland - the most important regulatory body of basic bodily functions: it is here that produced six major hormones called dominant - thyrotropin, adrenocorticotropic hormone (ACTH) and gonadotropin-releasing hormone 4, which regulate the function of the gonads. Thyrotropin speeds up or slows down the thyroid, and ACTH is responsible for the adrenal glands. The anterior lobe of the pituitary gland produces a very important hormone - growth hormone, also called growth hormone. This hormone is the main factor affecting the growth of bone, cartilage and muscle. Excessive production of growth hormone in the adult leads to acromegaly, which is manifested in increasing the bones, limbs and face. The pituitary gland is paired with the hypothalamus, with whom he is a bridge between the brain, peripheral nervous system and circulatory system. Communication between the pituitary gland and hypothalamus by using various chemicals that are produced by the so-called neyrosektornyh cells.

 

Epiphysis

The function of the pineal gland is not fully understood. Pineal gland produces compounds hormonal nature, melatonin and norepinephrine. Melatonin - a hormone which controls Sequence of phases of sleep, and norepinephrine affect the circulatory system and nervous system.

 

Regulation of the endocrine system

 

Endocrine control can be seen as a chain of regulatory effects, in which the result of the action of the hormone directly or indirectly affect the element that determines the content of available hormone.

The interaction typically occurs on a negative feedback loop: the effects of hormones on their target cell response by affecting hormone secretion source, causes suppression of secretion.



Positive feedback, in which the secretion is enhanced, is extremely rare.

The endocrine system is also regulated by the nervous and immune systems.

Endocrine diseases

 

Endocrine disease - is a class of diseases which result from one or more disorders of the endocrine glands. At the heart of endocrine diseases are hyperactivity, hypoactivity or dysfunction of the endocrine glands.

 

Tasks

Answer the questions

1) What is the endocrine system?

2) What organs produce and secrete specific substances directly into their blood or lymph?

3) Name one of the major glands of body?

 

Topic 11

Transport System

The circulatory system also called the cardiovascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from cells in the body to nourish it and help to fight diseases, stabilize body temperature and pH, and to maintain homeostasis.

The circulatory systems of all vertebrates, as well as of annelids (for example, earthworms) and cephalopods (squids, octopuses and relatives) are closed, just as in humans. Still, the systems of fish, amphibians, reptiles, and birds show various stages of the evolution of the circulatory system.

In fish, the system has only one circuit, with the blood being pumped through the capillaries of the gills and on to the capillaries of the body tissues. This is known as single cycle circulation. The heart of fish is, therefore, only a single pump (consisting of two chambers).

In amphibians and most reptiles, a double circulatory system is used, but the heart is not always completely separated into two pumps. Amphibians have a three-chambered heart.

 

In reptiles, the ventricular septum of the heart is incomplete and the pulmonary artery is equipped with a sphincter muscle. This allows a second possible route of blood flow. Instead of blood flowing through the pulmonary artery to the lungs, the sphincter may be contracted to divert this blood flow through the incomplete ventricular septum into the left ventricle and out through the aorta. This means the blood flows from the capillaries to the heart and back to the capillaries instead of to the lungs. This process is useful to ectothermic (cold-blooded) animals in the regulation of their body temperature.

Birds and mammals show complete separation of the heart into two pumps, for a total of four heart chambers; it is thought[citation needed] that the four-chambered heart of birds evolved independently from that of mammals.

Open circulatory system

The open circulatory system is a system in which a fluid in a cavity called the hemocoel bathes the organs directly with oxygen and nutrients and there is no distinction between blood and interstitial fluid; this combined fluid is called hemolymph or haemolymph. Muscular movements by the animal during locomotion can facilitate hemolymph movement, but diverting flow from one area to another is limited. When the heart relaxes, blood is drawn back toward the heart through open-ended pores (ostia).

Hemolymph fills all of the interior hemocoel of the body and surrounds all cells. Hemolymph is composed of water, inorganic salts (mostly Na+, Cl-, K+, Mg2+, and Ca2+), and organic compounds (mostly carbohydrates, proteins, and lipids). The primary oxygen transporter molecule is hemocyanin.

 

There are free-floating cells, the hemocytes, within the hemolymph. They play a role in the arthropod immune system.

Absence of circulatory system

Flatworms, such as this Helicometra sp., lack specialized circulatory organs

Circulatory systems are absent in some animals, including flatworms (phylum Platyhelminthes). Their body cavity has no lining or enclosed fluid. Instead a muscular pharynx leads to an extensively branched digestive system that facilitates direct diffusion of nutrients to all cells. The flatworm’s dorso-ventrally flattened body shape also restricts the distance of any cell from the digestive system or the exterior of the organism. Oxygen can diffuse from the surrounding water into the cells, and carbon dioxide can diffuse out. Consequently every cell is able to obtain nutrients, water and oxygen without the need of a transport system.

Some animals, such as jellyfish, have more extensive branching from their gastrovascular cavity (which functions as both a place of digestion and a form of circulation), this branching allows for bodily fluids to reach the outer layers, since the digestion begins in the inner layers.

 

Tasks

 

Are the sentences true either false?

1) The circulatory system also called the cardiovascular system

2) In fish, the system has two circuit

3) Amphibians have a three-chambered heart

 

 

Topic 13

Digestive System

 

Digestion is the breakdown of food into smaller components that can be more easily absorbed and assimilated by the body. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. In chemical digestion, enzymes break down food into the small molecules the body can use.

 

In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication, a form of mechanical digestion, and the wetting contact of saliva. Saliva, a liquid secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food. After undergoing mastication and starch digestion, the food will be in the form of a small, round slurry mass called a bolus. It will then travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion. Gastric juice mainly contains hydrochloric acid and pepsin. As these two chemicals may damage the stomach wall, mucus is secreted by the stomach, providing a slimy layer that acts as a shield against the damaging effects of the chemicals. At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which is waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes.

 

After some time (typically 1–2 hours in humans, 4–6 hours in dogs, 3–4 hours in house cats),[citation needed] the resulting thick liquid is called chyme. When the pyloric sphincter valve opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas, and then passes through the small intestine, in which digestion continues. When the chyme is fully digested, it is absorbed into the blood. 95% of absorption of nutrients occurs in the small intestine. Water and minerals are reabsorbed back into the blood in the colon (large intestine) where the pH is slightly acidic about 5.6 ~ 6.9. Some vitamins, such as biotin and vitamin K (K2MK7) produced by bacteria in the colon are also absorbed into the blood in the colon. Waste material is eliminated from the rectum during defecation.

Digestive systems

Digestive systems take many forms. There is a fundamental distinction between internal and external digestion. External digestion is more primitive, and most fungi still rely on it. In this process, enzymes are secreted into the environment surrounding the organism, where they break down an organic material, and some of the products diffuse back to the organism. Animals have a tube (gastrointestinal tract) in which internal digestion occurs, which is more efficient because more of the broken down products can be captured, and the internal chemical environment can be more efficiently controlled.

 

Some organisms, including nearly all spiders, simply secrete biotoxins and digestive chemicals (e.g., enzymes) into the extracellular environment prior to ingestion of the consequent "soup". In others, once potential nutrients or food is inside the organism, digestion can be conducted to a vesicle or a sac-like structure, through a tube, or through several specialized organs aimed at making the absorption of nutrients more efficient.

 

 

Tasks

Answer the questions

1) What is digestive system?

2) How many forms take the digestive system?

3) How come goes the digestive system in the human?

 

Topic 15


Date: 2015-12-11; view: 623


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