Why do we sneeze

The purpose of the lesson: On the basis of existing knowledge to find out the value of conditioned and unconditioned reflexes. To form students’ knowledge of the reflex regulation of body functions.


The purpose of the lesson: Based on the available knowledge to find out the value of conditioned and unconditioned reflexes. To form students’ knowledge of the reflex regulation of body functions.

I. Organizational moment

Ii. Updating reference knowledge

Why do we sneeze

Today at the lesson you will get acquainted with the reflex regulation of functions in the human body.

Q: What is a reflex?

– This is the response of the body to irritation, with the participation and control of the central nervous system.

Consequently, the nervous system regulates all functions in the body with the help of nerve impulses.

Q: What tissue is the nervous system formed?

Q: Tell us about the structure of the nervous tissue.

Nerve tissue is formed by two types of cells: the actual nerve cells are neurons, and the satellite cells are gliocytes (neuroglia).

Neurons perform the function of perception and conduction of nerve impulses. Glyocytes surround neurons and perform the function of support, nutrition and protection.

In the neuron distinguish the body and processes. Short and branching processes – dendrites, perceive and transmit impulses to the body of the neuron. Long processes – axons branch at the end. Axons transmit information from the cell body to another neuron or working body.

The nervous system is conventionally divided into two sections: the central nervous system and peripheral.

The central nervous system is represented by the brain and spinal cord, and the peripheral nerve and nerve nodes (clusters of neuronal bodies outside the central nervous system).

Q: What are nerve fibers?

– long processes of the dendrite or axon, surrounded by a shell.

Q: What are nerves?

– bundles of nerve fibers beyond the limits of the central nervous system, and heading to various organs of the body.

Iii. Study a new topic

We continue our acquaintance with the structure of the nervous system.

1. Classification of neurons

Depending on the functions performed, neurons are sensitive and motor (executive).

For sensitive neurons, impulses travel from the sense organs to the spinal cord and brain. Their bodies lie outside the CNS in the nerve nodes.

In motor neurons, impulses travel from the spinal cord and brain to the internal organs and muscles. Their bodies lie in the central nervous system.

Communication between sensory and motor neurons is carried out in the central nervous system using intercalated neurons. The bodies and processes of intercalary neurons do not extend beyond the limits of the central nervous system.

Nerves consisting of dendrites of sensitive neurons are called sensory.

Nerves consisting of axons of motor neurons are called motor ones.

Most nerves are mixed, as they contain both axons and dendrites. Therefore, the impulses along them go in two directions: from the senses in the central nervous system and from the central nervous system to the organs.

2. Reflexes congenital and acquired

At the core of the nervous system are reflexes. A person is born with a set of ready-made reflexes. The reflexes of a person are varied: with too bright light, we close our eyes, turn our heads to a loud sound, pull our hand away from a hot object, blink, if a speck gets in the eye, cough, sneeze, start to run away in danger. All these reflexes are performed without any conditions, so they are called unconditional. A man is born with them, therefore unconditioned reflexes are called inborn. They persist throughout life, do not change and are inherited.

But unconditioned reflexes alone are not enough for a person to adapt to changing environmental conditions. Therefore, on the basis of unconditioned reflexes, conditional ones are formed (which have arisen under certain conditions, under conditions of life experience). They are not permanent. May fade as unnecessary. For example, if for a long time you wake up on an alarm clock in the morning, your body will get used to it, and you will wake up at the same time in the future, but without the alarm clock. In the summer, when you do not need to get up early, your body will break the habit of this reflex.

3. Reflex arc

How is the reflex?

Gently touch the outer and inner corners of the eye, to the eyelashes. What’s happening? This is a blink reflex. Why do people blink, sneeze, pull back their hands?

In all organs of the body, under the skin there are receptors – the end of sensitive neurons. They transform irritation into nerve impulses. Nerve impulses in a sensitive way go to the central nervous system. There the information is processed by intercalary neurons. Then from the central nervous system on the motor path goes a signal to an organ or muscle.

The scheme of a reflex arc of a blink reflex (according to the textbook) is analyzed.

The way in which nerve impulses go from receptors to the executive organs is called a reflex arc.

Reflex arc scheme: receptor, sensitive neuron, intercalary neuron, motor neuron (executive), working organ. This is a complex reflex arc.

In a simple reflex arc, there are no intercalary neurons.

The accumulations of neurons in the central nervous system, causing a particular reflex action, is called the reflex center of this reflex.

All our actions occur with the participation and control of the central nervous system. For example, when a child sees a toy, he stretches his hand to it: through the executive nerve pathways, a command came from the brain – what to do. These are direct links. So the child grabbed the toy, and immediately the sensitive neurons sent signals about the results of the activity. This is feedback. Thanks to them, the brain controls the accuracy of the command, makes adjustments to the work of the executive bodies.

Why do we sneeze

  1. What is a reflex?
  2. What reflexes are typical for a person?
  3. What is the value of reflexes?
  4. Can a reflex arc control the work of executive bodies?
  1. The basic principle of the NA – reflex.
  2. With the help of reflexes, the interaction of various systems of the whole organism and its adaptation to changing environmental conditions is established.
  3. Due to the reflex activity, the body quickly reacts to various effects of external and internal environment.
  4. The path along which the reflex is performed is called a reflex arc.
  5. Reflex arc can not control the performance of the reflex. Control is carried out by the central nervous system.
Like this post? Please share to your friends:
Leave a Reply