Physiology of the human brain

The physiology of the brain stem Features of development of nervous

structures of a brain stem

Petrozavodsk State University Institute of physical culture, sports and tourism

Department of Life Safety and Health Saving Technologies

Developer:

Blazhevich Lyubov Evgenyevna,

lecturer of the department of life safety and health saving technologies

July, 2019

Main regions of the brain

The human brain consists of parts:

o Telencephalon (cerebral hemispheres)

o Diencephalon(thalamus and hypothalamus)

o Mesencephalon (midbrain)

o Cerebellum

o Pons

o Medulla oblongata

Neural structures of the brain stem

The brain stem consists of these parts:

o Diencephalon(thalamus and hypothalamus)

o Mesencephalon (midbrain)

o Cerebellum

o Pons

o Medulla oblongata

General structure of the brain

Structure of the brain

Grey matter

Includes neuron cell bodies

Gray matter forms ganglia

White matter

Includes nerve fibers

White matter forms nerve pathway

Cellular structure of the brain

The brain consists of two types of cells

Neurons

function:

Generate electrical impulses known as action potentials and send signals

to specific target cells

Glial cells (neuroglia)

function:

Provide structural support, metabolic support, insulation, and

guidance of development

General functions of the brain

General functions of the brain

Reflex function

This function is carried out by nerve ganglia

Function of nerve impulse conduction

from neuron to another cell

This function is carried out by nerve fibers and pathways

Structure and functions of the medulla oblongata

(in modern clinical usage the word bulbar is retained for terms that relate to the medulla oblongata, for example , bulbar palsy)

The most significant structures on the anterior surface of the medulla oblongata are:

o Pyramids (the pyramids contain the pyramidal tracts, the corticospinal and the corticobulbar tracts of the nervous system)

o Olivary bodies (also called olives, the nerve center of posture and body balance)

Functions of the medulla oblongata

Somatic functions

Vegetative function

• Support of body posture

• Support of muscular balance

• Regulation of cardiovascular system functions

• Regulation of respiratory system functions

• Regulation of the functions of the digestive system

Structure and functions of the mesencephalon (midbrain)

o The principal regions of the midbrain are the tectum, the cerebral aqueduct, tegmentum, and the cerebral peduncles.

o The tegmentum area includes various different structures, such as the reticular formation, several nuclei controlling eye movements, the red nucleus (muscle tone center), the substantia nigra (center of motor functions).

o Through the middle brain is the reticular formation (the center of activation and deactivation of the neuronal activity, the center of sleep and wakefulness).

Functions of the mesencephalon (midbrain)

o Vision

o Hearing

o Motor control

o Sleep/wake

o Arousal (alertness)

o Temperature regulation

Structure and functions of the diencephalon

Diencephalon consists of structures that are on either side of the third ventricle, including

o The thalamus

o The hypothalamus

o The epithalamus

o The subthalamus

Functions of the diencephalon

• The thalamus is the nerve center of all types of sensitivity

• The thalamus contains more than 30 nuclei, some of which are associative, some of which are switching

Thalamus

• The hypothalamus regulates homeostasis

• The hypothalamus is involved in endocrine function (affects the pituitary gland with liberins and statins)

Hypothalamus

• The epithalamus adjacent to the pineal gland (gland which produces the hormone melatonin)

• The epithalamus participates in the regulation of circadian rhythms

• The epithalamus participates in the regulation of endocrine function

• The epithalamus participates in the regulation of cognitive and emotional function

• The epithalamus participates in the regulation of motor function

Epithalamus

Anatomy of the brain

(Из: Синельников Р.Д. Атлас анатомии человека. — М., 1972. — Т. III.) (From: Sinelnikov R. D. Atlas of human anatomy. — M., 1972. — Vol. III.)

1. Medulla oblongata 1.1 Pyramids 1.2 Olivary bodies 2. Pons 3. Cerebellum 4. Mesencephalon 4.1 Tectum (located dorsally

relative to the ventricle of the brain)

4.2 Cerebral aqueduct (the

ventricle of the brain)

4.3 Tegmentum (located

ventral relative to the ventricle of the brain)

4.4 Cerebral peduncles

1 1.2

1.1

2 3

4 4.1

4.2

4.3

4.4

Features of the development of the medulla oblongata and pons

• The medulla and pons to birth reach a large degree of development, and their differences from those of an adult consist only in the degree of myelination of nuclei and pathways. Their weight in a newborn is 8 g, or 2% of the mass of the brain, in an adult - only 1.6% .

• The nuclei of the cranial nerves of the medulla oblongata are formed early. Their development is associated with the formation of regulatory mechanisms of respiration, cardiovascular, digestive and other systems in ontogenesis. Vagus nerve nuclei are detected from the 2nd month of fetal development. By one and a half years of life of the child increases the number of cells in the nuclei of the vagus nerve. Significantly increases the length of the processes of neurons. In a 7-year-old child, the nucleus of the vagus nerve is formed in the same way as in an adult.

Features of the development of the cerebellum

• The cerebellum is underdeveloped in comparison with the brain, and this is especially true of the hemispheres, but in the first year of life it develops more than other parts of the brain. At the end of the first year of life, it reaches a final value of 10% relative to the brain.There is a large increase in the cerebellum in the period between the fifth and eleventh months of life, when the child learns to sit and walk. By birth, the mass of the cerebellum is 20 g on average, in 3 months it doubles, in 5 months it increases 3 times, by the end of the ninth month - in4 times. Then there comes a period of slow growth, but up to 6 years its mass reaches the lower limit of the mass in an adult (in boys 142 - 150 g, in girls 125 - 135g).

Features of the development of the

mesencephalon

• The midbrain at birth has a mass of 2.5 g. Its shape and structure do not differ from those of an adult. The brain water supply is wider, the middle cerebral nucleus of the trigeminal nerve and the oculomotor nerve have myelinated fibers. Black matter and reticular formation spread along the length of the middle brain, their cells are well differentiated, but do not contain the characteristic pigment that appears quite late, starting from the sixth month of life and sometimes almost to the period of puberty. Maximum development they reach about 16 years. The medial part of the black matter begins to myelinate in the first 2 - 3 months of life. Red nucleus is well expressed, it begins to be pigmented with a 2-year old and 4 year well painted. By birth, pyramidal fibers are myelinated, unlike cortical-bridge paths that do not have a myelin sheath by this period. They are myelinated from the 4th month of life.

Features of development of diencephalon

• The diencephalon is well developed by the time of birth, many of its fibers are myelinated. In 6 months, develop non-specific nuclei related to the reticular formation. Increased growth of the thalamus is observed at the age of 4 years, and the size of an adult it reaches to 13 years of life. The function of the sensory nuclei of the thalamus is carried out already in the newborn, which allows the child to distinguish between taste, temperature, tactile and pain. The functions of the nonspecific nuclei of the thalamus and ascending activating reticular formation of the brain stem in the first months of life are poorly developed, resulting in a short time of wakefulness of the child during the day

Questions and tasks:

1 • Read the text of the presentation

2

• Outline the content of the presentation in your notebook (use color or graphic highlighting of the main headings)

3

• Be prepared to verbally answer the questions:

• What are the General structure and General functions of the brain?

• What is the structure and function of the medulla oblongata?

• What is the structure and function of the mesencephalon?

• What is the structure and function of the diencephalon?

• What are the features of the development of nervous structures of the brain stem?

Recommended literature

• Нейрофизиология. Основной курс : учебное пособие / А.А. Лебедев, В.В. Русановский, В.А. Лебедев, П.Д. Шабанов. - Москва ; Берлин : Директ-Медиа, 2019. - 271 с. : ил. - Библиогр. в кн. - ISBN 978-5-4475-9973-7 ; То же [Электронный ресурс]. - URL: http://biblioclub.ru/index.php?page=book&id=499765 (07.07.2019).

• Солодков, А.С. Физиология человека: общая, спортивная, возрастная : учебник для высших учебных заведений физической культуры / А.С. Солодков, Е.Б. Сологуб. - 7-е изд. - Москва : Спорт, 2017. - 621 с. : ил. - ISBN 978-5-906839-86-2 ; То же [Электронный ресурс]. - URL: http://biblioclub.ru/index.php?page=book&id=461361 (07.07.2019).