Muscles and glands are، Introduction. When we want to take an object our brain gives an order and some muscles move the arm and hand.
This does not have more complication, but whathappens with the lungs, with the heart or with the stomach, which are constantly moving, including when we sleep?
muscles and glands are
Who gives the orders? and, what’s more, what happens when without thinking we withdraw the hand of a place when noticing that we are burning?
Who gives these orders? And another issue, what happens when the functioning of the nerves fails? And when the one that fails is our brain?
Can we trust then what we think?
Can not it be that what we see is actually different? There are diseases that consist of not being able to do without consuming certain substances (drugs) even though they harm us. Well, of all these interesting questions, this topic deals with.
Activities to be performed . Read the explanations about the effector organs and perform the Multiple Response Test 12.1 and the Relate drawings and names 12. Then, read the text about the main diseases of the nervous system and perform the Multiple Response Test 12.2 and the Crossword 12.
one . The effectors . They are the organs that execute the responses of the Nervous System. There are two types of effectors, which are muscles (also called ” motor effectors “) and exocrine glands (also called ” secretory effectors “). All effectors are stimulated by nerves ie they are “innervated”.
Nerves are called cranial nerves if they leave the skull or spinal nerves if they leave the spinal cord. The set of all the nerves forms the so-called Peripheral Nervous System. The motor effectors can be striated fiber muscles and voluntary contraction or smooth fiber muscles and involuntary contraction . The nervous system that innervates the muscles of voluntary contraction is called the Voluntary Nervous System and the nervous system that innervates the muscles of involuntary contraction and also the exocrine glands is called the Autonomic Nervous System orNeurovegetative .
two . The response of the Voluntary Nervous System . The response can be a reflex act or a voluntary act .
Reflexively . It is the one that occurs when the response is made in the spinal cord . Its nervous coordination consists of a sensitive neuron that drives a nerve impulse to the gray matter of the cord and transmits it to an intercalary or association neuron , which passes it to a motor neuron that stimulates the movement of a muscle fiber. It can also occur without intervention of the intercalary neuron, ie with only two neurons. It is a very fast and unconscious responsein situations of danger that need an immediate response, such as when we feel a puncture in a leg. The sensation of pain reaches the brain after the movement occurs. It is therefore a kind of short circuit in the normal course of a voluntary act, in order to achieve a very rapid response.
Voluntary act . It is the one that occurs when the response is elaborated in the brain . Its nervous coordination consists of a sensitive neuron that communicates with a neuron in the marrow , which communicates with a neuron that goes to the brain , where several neurons ( association neurons ) intervene and emit a response nervous impulse that descends through the brain. marrow and, through a motor neuron , it reaches the muscle. In this case there is awareness of the decided response before executing it.
3 . The response of the Autonomic Nervous System . This system controls the functions performed by our viscera independently of our will. For example heartbeat, respiratory movements, digestion, excretion, etc. It is constituted by some cranial nerves (leave the skull) and some spinal nerves (leave the medulla). There are two types of autonomic nervous system:
The sympathetic nervous system (SNS). It is the predominant in situations of danger . It provokes the appropriate actions for the rapid response such as: increase of the heart rate, dilatation of the bronchi to favor the entrance and exit of gases, increase of the sweating, decrease of the intestinal peristalsis to diminish the energy invested in the digestion, vasoconstriction of the arteries, dilation of the pupils so that more light enters, etc.
The parasympathetic nervous system (SNP). It is the one that predominates in resting situations . Causes adequate actions for relaxation and the investment of a lot of energy in the digestive function. These actions are: decreased heart rate, decreased respiratory rate, decreased sweating, increased intestinal peristalsis, vasodilation of the arteries, contraction of the pupils, etc.
The response of the autonomic nervous system is controlled by the hypothalamus but also presents reflex acts, the so-called visceral reflexes , such as changes in sweating and muscle tension in response to localized heat or intestinal mobility in response to a stimulus.
Multiple response test 12.1
List of drawings and names 12.1
Four . Diseases of the nervous system. The main ones are:
Anorexia nervosa . It is the continued behavior of not wanting to eat. It usually starts with a feeling of panic at the thought of excess weight. Paradoxically, this disease is favored if the person has a strong will and is self-demanding, two characteristics of the personality that are generally very positive for other human activities.
Autism . It is the tendency to retreat into the inner world itself and disinterested in external reality, accompanied by the inability to communicate. It can be a symptom of schizophrenia.
Bulimia . It is the excessive intake of food in response to a state of high anxiety. Excess weight causes the patient’s concern, which increases anxiety and thus intake, closing a vicious circle.
Dependence . It consists of the need to consume a certain substance in a habitual way to recover the normality of the functioning of the organism. It appears after the continued consumption of a certain drug or drug It can be physical (if not consumed there are spasms, tremors and sweating, the so-called withdrawal syndrome ) or psychic (yes there is discomfort but not a true withdrawal syndrome). According to the product, alcoholism , smoking and drug addiction are distinguished . The main drugs and their effects are: