NERVOUS SYSTEM

Central Nervous System (CNS) and Peripheral Nervous System (PNS)
The brain and its constituent parts are the most complex system ever known. With one trillion separate cells, each one in a continuous process of changing in response to chemical signals. From the moment of conception to the moment of death, the biology of the individual is changing. It is in this complexity that our species has found the capability to store the accumulated experience of thousands of generations – to create human culture. Our language, religions, governments, childrearing practices, technologies, economies are all man-made; yet all depend upon the remarkable capacity of the brain to make internal representations of the external world.
Biological Bases of Behavior• The Nervous System
• Endocrine Glands
The Nervous system
• The system that controls and regulates the structure and function of the brain, spinal cord, nerves, and the nerve cells; it maintains coordination between the nervous system and the rest of the bodily systems.
• It is responsible for the internal communication system that ensures the integrated functioning of the various systems.
Some Interesting Facts about the Nervous system
• The nervous system consists of billions of highly specialized nerve cells called neurons.
• Nerve impulse is an electrical impulse that travels along the nerves at a speed of around 400km/ hour.
• Every second, a number of these impulses can pass along nerves.
• Brain cells never re grow; once destroyed or dead, they can not be replaced.
• Nerve fibers are very thin and fine in size; a hundred of them lying side by side would fit into just 1mm.
• The brain is divided into two visible parts or hemispheres; the left hemisphere controls the right side of the body, and the right controls the left side.
• The total surface area of the cerebral cortex is approximately 2.5sq.ft. if you spread it flat.
NEURON
A nervous system cell is constituted in such a way that it is specialized in receiving, processing, and/or transmitting information to other cells.
Structure of a Neuron• Dendrites: Receivers of incoming signals; branch fibers extending outward from the cell body.
• Soma: The cell body containing the cytoplasm and the nucleus of the cell; cytoplasm keeps it alive.
• Axon: The nerve impulses travel from the soma to the terminal buttons through the extended fiber of a neuron i.e., axon.
• Terminal Buttons: Swollen, bulblike structures at one end of the axon; the neuron stimulates the nearby glands, muscles, or other neurons Connection between nerve cells
• Synapse: the gap between one neuron and the other.
• Synaptic Transmission: the procedure through which information is relayed from one neuron to another across the synaptic gap.
• Neurotransmitters: The post synaptic neuron is stimulated by the chemical messages released from neurons; they cross the synapse from one neuron to another.
The Chemical Messages• The neurons follow an all-or-none law…. either a neuron will be firing or resting /off.
• Excitatory Message: The chemical message that makes it more likely that the receiving neuron will fire and the action potential will travel down its axon.
• Inhibitory Message: The chemical message that inhibits a receiving neuron from firing so that the action potential does not travel down its axon.
Major Varieties of Neurons
• Sensory Neurons (afferent): they carry messages toward the Central Nervous System from the sensory receptor cells.
• Motor Neurons (efferent): they carry messages away from the Central Nervous System toward the muscles and glands.
• Inter-Neurons: they relay messages from sensory neurons to other inter-neurons and/or to motor neurons.

MAIN PARTS OF THE NERVOUS SYSTEM• The Peripheral Nervous System
• The Central Nervous System
CENTRAL NERVOUS SYSTEM (CNS)
• Brain receives the information from all over the body (primarily in terms of stimulation via sensation), interprets it, and decides how to respond.
• The brain’s function is similar to that of a computer; there is a central processing unit (CPU), the output comes in, and the CPU analyses it and responds to it.
The Brain
• The center of the nervous system.
• The vital organ that is responsible for the functions of seeing, hearing, smelling, tasting, thinking, feeling, remembering, speaking, dreaming, information processing, and a lot more.
• The regulator of basic survival functions such as breathing, resting and feeding.
• It is responsible for abstract level functions such as decision making, foresight, and problem solving.
• The spinal cord is an information highway connecting the PNS to the brain.
• Information travels to and from the brain by way of spinal cord.
Functions of the Various Structures of the Brain
• Regulation of the internal systems
• Reproduction
• Sensation
• Motion
• Adaptation to the varying environmental demands
Structure of Brain• The deeply grooved structure lies safely and securely in our skull.
• The average adult human brain weighs 1.3 to 1.4 kg (approx. 3 pounds).
• If you look at it from the outside the brain is pinkish gray in color; soft, spongy, and mottled.
• The brain contains billions of nerve cells (neurons) and trillions of "support cells".
Parts of the Brain
The brain is made of three main parts:
a. Fore brain
b. Mid brain
c. Hind brain
Fore Brain
i. Cerebrum
ii. Thalamus
iii. Hypothalamus
iv. Limbic system
Mid Brain
i. Tectum
ii. Tegmentum
iii. Reticular formation
iv. Substantia nigra
Hind Brain
i. Cerebellum
ii. Pons
iii. Medulla oblongata
Brain Stem and Cerebellum
Located underneath the limbic system the brain stem, containing four structures, is found in all vertebrates.
It contains four structures:
1. Medulla
2. Pons
3. Reticular formation
4. Thalamus
o Responsible for basic survival functions such as breathing, heartbeat, and blood pressure.
1. Medulla/ Medulla Oblongata• Located at the top of the spinal cord and continuous with it.
• Damage to Medulla can be fatal as it is the center responsible for vital functions i.e., respiration, heart beat, and blood pressure.
• Contains ascending & descending tracts that communicate between the spinal cord & various parts of the brain.
• At medulla, nerves ascending from the body and descending from the brain cross over; hence the left side of the body is connected to the right side of the brain and vice versa.
• Contains 3 vital centers:
1-Cardio inhibitory center: regulates heart rate.
2-Respiratory center: regulates the basic rhythm of breathing.
3-Vasomotor center: regulates the diameter of blood vessels.
2. Pons
Pons = Latin word for bridge
• Bridge connecting spinal cord with brain and parts of brain with each other.
• The pons seems to serve as a relay station carrying signals from various parts of the cerebral cortex to the cerebellum.
• Nerve impulses coming from the eyes, ears and touch receptors are sent on the cerebellum.
• The pons also participates in the reflexes that regulate breathing.
• It has parts that are important for the level of consciousness and for sleep.
3. Reticular Formation• The reticular formation is a region running through the middle of the hindbrain and into the midbrain.
• A dense network of nerve cells.
• It keeps the brain alert even during sleep.
• It makes the cerebral cortex attend to new stimulation by arousing it.
• Long fibrous tracts of reticular formation run into the thalamus.
• Needed for arousal from sleep & to maintain consciousness.
• Serious damage to reticular formation may result into a coma.
4. Thalamus
The pair of egg-shaped structures located at the top of the brainstem.
• Incoming sensory information is channeled to the appropriate area of the cerebral cortex by thalamus, so that it is processed there.
• Thalamus acts like a relay station…. the brain’s sensory switchboard; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla.
• It receives information from the sensory neurons and routes it to the higher brain regions that deal with vision, audition, taste and touch.
Cerebellum
• "Cerebellum" comes from the Latin word for "little brain”. The cerebellum is located behind the brain stem.
• Cerebellum is somehow similar to the cerebral cortex: the cerebellum is divided into hemispheres and has a cortex that surrounds these hemispheres.
• It carries 10% of the weight of the brain.
• It contains as many neurons as in the rest of the brain.
• Its function is to coordinate body movements i.e. coordination, maintenance of posture & balance.
• Damage to cerebellum results into jerky and uncoordinated body movements.
LIMBIC SYSTEM• Evolutionarily the structure of limbic system is rather old.
• The limbic system, often referred to as the "emotional brain", is found buried within the cerebrum.
• At the border of the brainstem and cerebral hemispheres it is a doughnut-shaped system of neural structures; associated with emotions e.g. fear and aggression, and drives like hunger and sex; regulates body temperature, blood sugar level and blood pressure.
Structures within the Limbic System
i. Hippocampus
ii. Amygdala
iii. Hypothalamus
Amygdala• Two almond-shaped neural clusters in the limbic system that are linked with emotions.
• They are related with aggression and fear.
Hippocampus• The hippocampus is the part of the limbic system that is important for memory and learning.
Hypothalamus• One of the smallest structures in the brain.
• The neural structure lying below (hypo) the thalamus; Composed of several nuclei. Small bundles of neurons that regulate physiological processes involved in motivated behavior e.g. hunger, thirst, regulation of body temperature.
• Hypothalamus acts as the body’s Thermostat.
• Helps govern the endocrine system via the pituitary gland.
• Is linked to emotions.
Homeostasis
Hypothalamus maintains the body’s internal equilibrium e.g. looking for food when energy levels are low, causing constriction of the blood vessels when body temperature falls.
Cerebrum• Largest part of the human brain, associated with higher brain functions such as thought and action..
• Occupies 2/3 of the brain’s total mass
• Consists of two symmetrical halves or hemispheres; The right cerebral hemisphere controls the left side of the body and vice versa.
• The hemispheres are connected by Corpus Callosum, a thick mass of nerve fibers.
• Cerebrum regulates the brain’s higher cognitive and emotional functions.
Cerebral Cortex
o Coming from the Latin word for "bark”, cortex means covering, or sheath; the cortex is a sheet of tissue making up the outer layer of the brain.
o About 1/10 of an inch in thickness, the cortex is composed of some 30 billion nerve cells and 300 trillion synaptic connections.
o It is the body’s ultimate control and information-processing center.
o The cerebral cortex is greatly convoluted in humans. These convolutions include:
1. Sulci (singular Sulcus) i.e. small grooves.
2. Gyri (singular Gyrus) i.e. large grooves also called “Fissures”.
Grey matter
• Cerebral cortex mostly consists of glia (glial cells), cell bodies, dendrites and
interconnecting neurons; they give the cerebral cortex a grayish brown appearance, commonly known as ‘Grey Matter”.
White Matter
• Beneath the cerebral cortex lie millions of axons that connect the neurons of the cerebral cortex to those located elsewhere in the brain.
• The large myelin gives tissue an opaque white appearance known as “White Matter”.
Cerebral Lobes
a. Frontal lobe
b. Parietal lobe
c. Temporal lobe
d. Occipital lobe
• Each lobe controls a different range of activities.
• Each hemisphere is vertically divided by the central sulcus, a groove.
• The lateral fissure, another groove divides each hemisphere horizontally.
a. Frontal lobe
Associated with motor control and cognitive activities; reasoning, planning, decision making, problem solving, movement and speech (Broca’s Area).
b. Parietal lobe
Associated with controlling incoming sensory information; thus affecting movement, orientation, recognition, perception of stimuli.
c. Temporal lobe
Associated with perception and recognition of auditory stimuli, memory & speech.
Wernicke’s area: concerned with the understanding of language is located here
d. Occipital lobe
Associated with visual processing.
Cranium
The brain is enclosed in the cavity of skull or cranium consisting of eight hard bones; One frontal bone, two parietal bones, two temporal bones, one occipital bone, one sphenoid bone, and one ethmoid bone.
Membranes of the Brain
• Between the surfaces of the brain and the skull, there are three layers of membrane called the meanings, which completely cover the brain and spinal cord.
• These three membranes are:
1. Dura Matter
2. Arachnoid
3. Pia Matter
Cerebrospinal Fluid (CSF)• The subarachnoid space contains a fluid called cerebrospinal fluid (CSF), a clear, colorless fluid covering the entire surface of central nervous system.
• The total volume of CSF is 125-150 ml.
• Total production of CSF is about 400-500 ml/day (about 0.36ml/min).
Association Areas
• Areas in the cerebral cortex that are not involved in primary motor and sensory functions; rather they are involved in higher mental functions such as learning, remembering, thinking and speaking.
• Association areas in the Frontal Lobes are concerned with judging and planning;
• Damage may lead to intact memory but inability to plan out something. Personality
• may also be affected.
• Association areas of other lobes are related to other mental functions; i.e. Temporal Lobe enables us to recognize faces; damage to this area causes inability to identify people (although facial features can be described), and gender and approximate age too.
• Association areas in the posterior lobes are involved in perception and memory. Damage leads to difficulty in perceiving speech.
Spinal Cord
• Continuation of the Medulla Oblongata.
• The spinal cord is about 45 cm long in men and 43 cm long in women and weighs about 35-40 grams.
• The vertebral column (back bone), encapsulating the spinal cord, is about 70 cm long comprising vertebra in the vertebral column.
• The spinal cord is much shorter than the vertebral column.
• Signals arising in the motor areas of the brain travel back down the cord and leave in the motor neurons.
• The spinal cord also acts as a minor coordinating center responsible for some simple reflexes like the withdrawal reflex.
Reflex - rapid (and unconscious) response to changes in the internal or external environment, needed to maintain homeostasis
Reflex arc: the neural pathway over which impulses travel during a reflex. The components of a reflex arc include:
1. Receptor - responds to the stimulus
2. Afferent pathway -- sensory neuron
3. Central Nervous System

PERIPHERAL NERVOUS SYSTEM (PNS)
Consists of the spinal and cranial nerves; these connect the CNS to the rest of the body. PNS connects the body’s sensory receptors to the CNS, and the CNS to the muscles and glands.
The part of the nervous system that includes all parts of the nervous system except the brain and the spinal cord
• Includes:
i. Somatic Division / Somatic Nervous System/ SNS
ii. Autonomic division / Autonomic Nervous System/ ANS
Parts of Peripheral Nervous System
PNS has two important parts
1. Skeletal/Somatic Nervous System
• Controls the voluntary movements of our skeletal muscles.
• It reports the current state of skeletal muscles and carries instructions back.
• Controls the voluntary movements of the skeletal muscles.
• Controls the involuntary movements all over the body; movements of the heart, lungs, stomach, glands and other organs.
2. Autonomic Nervous System (ANS)
• Considered as the “self governing or self-regulatory mechanism” because of its involuntary operation.
• Controls the glands and muscles of internal organs e.g. heart, stomach, and glandular activity.
• A.N.S. has a dual function; i.e. both arousing and calming.
• Comprises two sub systems; Sympathetic and parasympathetic nervous systems.
a. Sympathetic Nervous System (SNS)
• This part of ANS arouses us for defensive action…. fight or flight.
• If something alarms, endangers, excites, or enrages a person, the sympathetic nervous system accelerates heart beat, slows digestion, raises the sugar level in blood, dilates the arteries and cools the body through perspiration; makes one alert and ready for action.
b. Parasympathetic Nervous System (PNS)
When the stressful situation subsides, parasympathetic nervous system begins its activity.
• It produces an effect opposite to that of sympathetic nervous system.
• It conserves energy by decreasing heart beat, lowering blood pressure, lowering blood sugar and so on. In daily life situations, both sympathetic and parasympathetic systems work together to keep us in steady internal state maintaining the homeostasis.
Studying the Structure and Function of the Brain
• Electroencephalogram (EEG): recording of the electrical signals being transmitted within the brain, through electrodes attached to the skull.
• Computerized Axial Tomography (CAT): a computer constructs an image of the brain by combining thousands of separate X-rays taken from slightly different angles.
• Magnetic Resonance Imaging (MRI): the scan produces a powerful magnetic field to provide a computer generated, detailed image of the structure of the brain.
• Super Conducting Quantum Interference Device (SQUID): a scan sensitive to minute changes in the magnetic field occurring when neurons are firing.
• Positron Emission Tomography (PET): a scan showing biochemical activity within the brain at any given moment.

ENDOCRINE SYSTEM
Endocrine system is a collection of glands that produce hormones that regulate body's growth, metabolism, and sexual development and function. The hormones are released into the bloodstream and transported to tissues and organs throughout the body.
Although there are eight major endocrine glands scattered throughout the body, they are still considered to be one system because they have similar functions, similar mechanisms of influence, and many important interrelationships.
• Endocrine glands are known as the “Managers of Human Body”.
• Endocrine system is the system in which a number of glands secrets numerous hormones directly into the blood stream which regulate:
o Body’s growth
o Metabolism
o Sexual development and functions, and
o Other vital functions of the body
o Endocrine glands are ductless glands that secrete their hormones directly into the bloodstream.
o Hormones act as chemical messenger controlling various functions, reaching to the tissues and other vital organs of the body.
Pineal Gland
• The pineal gland, also known as pineal body, is found in the brain stem.
• It is small and cone-shaped in structure
Main function:
O Affects reproductive development
O Daily physiologic/ biological cycles
Pituitary Gland
Size and shape
It is a small gland__ diameter of about 1 centimeter or size of a pea.
Location
• It is connected with the hypothalamus by a slender stalk and also surrounded by bone.
• Secretes a number of different hormones that influence/affect various other endocrine glands.
• There are two distinguishable regions in the gland that have different secretions and functions:
a. The anterior lobe
b. The posterior lobe
a. Hormones of Anterior Lobe
Growth Hormone: Protein that regulates and also stimulates the:
• Growth of bones,
• Muscles, and other organs of the body by promoting protein synthesis.
The effect of this hormone is important and very much apparent because it affects height.
Growth Hormonal Problems
Dwarfism
If there is very little or no secretion of this hormone in a child, then the child may become a pituitary dwarf__ small in stature.
Gigantism
• If there is too much secretion of this hormone in the body, then there is exaggerated bone growth in a person and the person become exceptionally tall or a giant.
• This rare condition is usually caused by a pituitary tumor and can be treated by removing the tumor.
• When the pituitary gland fails to produce adequate amounts of growth hormone, a child's growth in height is impaired/ disturbed.
• Hypoglycemia (low blood sugar) may also occur in children who have deficiency of this growth hormone __ affects particularly infants and young children with this condition.
Thyroid-stimulating hormone: Affects the glandular cells of the thyroid so that it secretes thyroid hormone. The thyroid gland become enlarged and secretes too much thyroid hormone if there is hyper secretion of thyroid- stimulating hormone.
Adrenocorticotropic hormone: Cortical hormones especially cortisol are secreted when it reacts with the receptor cells in the cortex of the adrenal gland.
Gonadotropic hormones: Regulate the development, growth, and function of gonads and ovaries by reacting along with receptor cells present in these organs.
Prolactin Hormone: Helps in promoting the development of glandular tissues in the female breasts during pregnancy and as a result stimulates milk production after the birth of the infant.
b. Hormones of the Posterior Lobe
These hormones are:
i. Antidiuretic hormone
• Helps in the reabsorption of water by the kidney tubules__ as a result of which less amount of water is lost from the body as urine.
• This system/ mechanism conserve water for the body.
ii. Oxytocin
• Helps in the contraction of smooth muscles in the walls of the uterus.
• It also stimulates the ejection of milk from the lactating breast.
3. Hypothalamus
• Part of the central nervous system that is involved in controlling and activating involuntary functions of the body such as,
• Hormonal system
• Other body functions as well__ regulating sleep and stimulating appetite

THYROID GLAND
Type, Location and Lobes• Very vascular organ and is located in the neck.
• Consists of two parts/ lobes, one on each side of the trachea, just below the larynx or voice box.
• These two lobes are connected by a narrow band of tissue, called the ‘isthmus’.
• This gland consists of follicles, which produce thyroxin and triiodothyronine hormones.
• These hormones contain iodine--- about 95% of most functioning hormone is thyroxin and the remaining 5% is triiodothyronine__ both require iodine for their synthesis.
• Secretion is regulated by a negative feedback mechanism.
Calcitonin
• Secreted by Para follicular cells of the thyroid gland.
• Opposes the action of the parathyroid glands by reducing the calcium level in the blood.
• If calcium level in the blood becomes too high, calcitonin is secreted until calcium ion levels decreases to normal.
Iodine Deficiency
• Thyroid enlargement is called “goiter” or “iodine deficiency goiter”.
• If there is a deficiency of iodine in the body, then thyroid produce insufficient hormones required by the body__ causing the thyroid- stimulating hormone of the pituitary gland (anterior lobe) to secrete its hormone. This results in the increase in size of the thyroid gland but it is unable to make enough hormones, because it is lacking the raw material for production i.e. iodine.
Parathyroid Gland
Location, Type, Amount, Hormone
• Parathyroid gland consists of four small masses of epithelial tissue that are embedded in the connective tissue capsule, on the posterior side of the thyroid glands.
• Secretes ‘parathyroid hormone’ or ‘parathormone’.
• Most important regulator of blood calcium levels, secreted in response to low blood calcium levels, and its function is to increase calcium levels in the body.
Deficiency/ insufficient secretion of parathyroid gland
• Insufficient secretion of parathyroid hormone ‘hypoparathyroidisms’, leads to increased nerve excitability.
• Low blood calcium level in the body triggers spontaneous and continuous nerve impulses, which in turn stimulate muscle contraction.

Pancreas--- Islets of Langerhans• A long, soft organ that lies transversely along the posterior abdominal wall, posterior to the stomach, and extends from the region of the duodenum to the spleen. a. Exocrine portion of this hormone secretes digestive enzymes that are carried by a duct to the duodenum
B. The endocrine portion consists of the pancreatic islets, and
C. secretes glucagons and insulin.
Alpha Cells in Pancreatic Islets
Secrete hormone called ‘glucagons’ when there is a low concentration of glucose in the blood.
Beta Cells in the Pancreatic Islets
After the alpha cells, beta cells secrete hormone called ‘insulin’ as a result of high concentration of glucose in the blood.

ADRENAL GLAND
Synthesis and Location
• Developed from different embryonic tissues, it secretes various hormones.
• The adrenal/ suprarenal is a paired gland and located near the upper portion of each kidney.
Division of Adrenal Gland
Each gland is divided into two parts
a. An outer cortex and
b. An inner medulla
• The cortex and medulla of the adrenal gland are just like the anterior and posterior lobes of the pituitary gland.
• The adrenal cortex is essential to life because it has very important functions to perform, but the medulla may be removed with no life-threatening effects.
• Hypothalamus effects and influences both portions of the adrenal gland but it involves different mechanisms i.e. adrenal cortex is regulated by negative feedback which involves hypothalamus and adrenocorticotropic hormone.
• Medulla is regulated by nerve impulses of hypothalamus.
Hormones of the Adrenal Cortex
• The adrenal cortex consists of three different portions/ regions, each region produce different type of hormones.
• Chemically, all these cortical hormones are steroid.
a. Mineral corticoids
• Secreted by the outermost region of the adrenal cortex.
• The main/ principal hormone of mineralocorticoid is aldosterone, which acts to store/ conserve sodium ions and water in the body.
b. Glucocorticoids
• Secreted by the middle region of the adrenal cortex.
• The main/ principal hormone of glucocorticoid is cortisol, which increases blood glucose/ sugar level in the body.
c. Gonadocorticoids
• Also known as the sex hormones.
• These are secreted by the innermost region of the adrenal cortex.
• Adrenal cortex hormones, androgens (male hormones) and estrogens (female hormones), are secreted in minimal amounts in both sexes, but their effect is usually influenced by the hormones from the testes and ovaries.
• In females, the masculinization effect may become more evident after menopause. This occurs because the estrogen levels from the ovaries decrease.
Hormones of Adrenal Medulla
• Develops from neural tissues.
• Secretes two types of hormones,
o Epinephrine and
o Nor epinephrine
• These are secreted in response to stimulation by sympathetic nerve, especially during stressful situations.
• Lack of hormones from the adrenal medulla produces no significant effects,
• Hyper secretion, e.g., in case of a tumor, results in prolonged or continual sympathetic responses.
Gonads• Primary reproductive organs are testes in the male and the ovaries in the female.
• These organs are responsible for producing the sperm and ova, but they also secrete other hormones, and that is why they are considered to be endocrine glands.
Testes• Male sex hormones (as groups) are called androgens of which the most important and influential is ‘testosterone’; secreted by the testes.
• Small amount is also produced by the adrenal cortex.
• Production of testosterone begins before birth. i.e. during fetal development that continues for a short time after birth, nearly ceases during childhood, and then resumes at puberty.
• This steroid hormone is responsible for:
O The growth and development of the male reproductive organs.
O Increase in the size of skeleton and muscular growth.
O Larynx enlargement, accompanied by voice changes.
O Growth and distribution of body hair.
O Increased male sexual drive.
O It’s secretion is controlled and regulated by a negative feedback system and involves release of hormones from the hypothalamus and gonadotropins from the anterior pituitary.
Ovaries• Two groups of female sex hormones are produced in the ovaries i.e.
o Estrogens and
o Progesterone
Contribute to the development and function of the female reproductive organs and sex characteristics
i. Estrogen
Estrogen (on the onset of puberty) activates/ promotes:
o Development of female bodily characteristics.
o Distribution of fats in the body.
o Maturation of reproductive organs .
ii. Progesterone: causes the uterine lining to become thick, preparing uterus for pregnancy.
• Together both progesterone and estrogen are responsible for a number of changes occurring in the uterus.
Other Endocrine Glands
• In addition to the major endocrine glands and their system, there are various other organs, which are involved, in some hormonal activity or function. These include:
i. Thymus
ii. Stomach
iii. Small intestines
iv. Heart, and
v. Placenta
i. Thymosin
Hormone produced by the thymus gland, which has an important role in the development of the body's immune system.
ii. Gastrin
• Gastric mucosa (lining of the stomach) produces a hormone, called gastrin that is secreted when the food is present in the stomach.
• Stimulates the production of ‘hydrochloric acid’ and the enzyme ‘pepsin’, which are involved in the digestion of food.
iii. Secretin and Cholecystokinin: The mucosa of the small intestine secretes these hormones.
• Secretin stimulates the pancreas to produce a neutralizing agent__ bicarbonate-rich fluid that neutralizes the stomach acid.
Cholecystokinin
• Stimulates contraction of the gallbladder, which result in the releases of bile.
• Also activate the pancreas to secrete digestive enzyme.
• Atrial Natriiuretic Hormone, or Atriopeptin
• Heart also function as an endocrine organ
• In addition to its major role of pumping blood, has special cells in the wall of the upper chambers of the heart ‘atria’, secretes hormone called atrial natriiuretic hormone, or atriopeptin.
Placenta
Develops in the pregnant female
It is a source of nourishment and gaseous exchange for the developing fetus
Also serves as a temporary endocrine gland
Chorionic gonadotropin: One hormone that placenta secretes in human beings.
DISEASES RESULTING FROM ABNORMAL SECRETION OF ENDOCRINE GLANDS• Too much or too less secretions of endocrine glands can be harmful for the body.
• These secretions can be treated by controlling the over production, providing the essentials for production, or replacing hormones.
• Some of such abnormalities are:
DIABETES
Type 1 Diabetes
• Develops when pancreas fails to produce enough insulin.
• Symptoms include excessive:
O Thirst
O Hunger
O Urination, and
O weight loss
• In children and teens, the condition is usually an ‘autoimmune disorder”___ specific immune system cells and antibodies produced by the child's immune system that attack and destroy the cells of the pancreas that produces insulin.
• Can cause long-term complications such as:
O Kidney problems
O Nerve damage
O Blindness
O And early coronary heart disease and stroke
Treatment
In order to control blood sugar levels and reduce the risk of developing diabetes complications, children with this condition need regular injections of insulin
Type 2 diabetes
In this, the body is unable to respond to insulin normally, like in type 1 diabetes
• Children and teens with this condition are overweight.
• It is also believed that excess body fat plays a role in the insulin resistance that characterizes the disease.
• In recent years the rising prevalence of this type of diabetes in children played a crucial role in increasing rates of obesity among children and teens. The symptoms and possible complications of type 2 are the same as those of type 1.
Some children and teens can control their blood sugar level with:
O Dietary changes
O Exercise
O Oral medications
O But many have need to take insulin injections like patients with type 1 diabetes.

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Sarfraz Mayo