Unveiling the Human Endocrine System
Delve into the intricacies of the human endocrine system with a focus on exocrine and endocrine glands, their functions, and the role of hormones as chemical messengers controlling various bodily functions like growth and reproduction.
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LIFE SCIENCES GRADE 12 CAPS STRUCTURED, CLEAR, PRACTICAL - HELPING TEACHERS UNLOCK THE POWER OF NCS KNOWLEDGE AREA: Life Processes in Plants and Animals TOPIC 3.1: Human Endocrine system The Endocrine Glands
SUMMARY OF PRESENTATION: The Endocrine System Exocrine and Endocrine Glands and their Differences Differences between the Nervous System and Endocrine System Endocrine glands and their Function Feedback Mechanism
THE ENDOCRINE SYSTEM: The body has 2 types of glands. These are exocrine and endocrine glands. Exocrine glands are glands that pour their secretions into ducts, which carry their secretions to where they are needed. Salivary glands and sebaceous glands are some examples of exocrine glands in the body
THE ENDOCRINE SYSTEM: Endocrine glands are glands that pour their secretions into the blood and the blood carries the secretion to where they are needed. The thyroid and adrenal glands are some examples of endocrine glands.
TERMINOLOGY: TERM: Exocrine gland DEFNITION: USE IN SENTENCE: Refers to glands that pour their secretions into ducts, which carry the secretions to where they are needed. Since sweat is carried by the sweat ducts, the sweat gland is an example of an exocrine glands.
TERMINOLOGY: TERM: Endocrine Gland DEFINITION: USE IN SENTENCE: Refers to glands that pour their secretions into the blood and the blood carries the secretion to where they are needed. The hormones insulin and glucagon are poured directly into the blood, therefore the pancreas is an example of an endocrine gland.
THE ENDOCRINE SYSTEM: We must look at the endocrine glands in some detail. The Endocrine Glands: The secretions of the endocrine glands are called hormones. Now lets look at these hormones.
THE ENDOCRINE SYSTEM: The Hormones: Hormones are chemical messengers. They are mostly protein in nature. Functions of Hormones: They control a wide variety of functions such as growth and reproduction. 1.
THE ENDOCRINE SYSTEM: The hormones stimulate certain organs, the organs they stimulate is called target organs. They are a part of an integrated system. They bring about co-ordination and homeostasis. 2. 3. 4.
TERMINOLOGY: TERM: Hormone DEFINITION: USE IN SENTENCE: Are chemical messengers that are protein in nature. The TSH and ADH are examples of hormones.
EXOCRINE AND ENDOCRINE GLANDS AND THEIR DIFFERENCES: Can you tabulate these differences?
EXOCRINE AND ENDOCRINE GLANDS AND THEIR DIFFERENCES: Differences between endocrine and exocrine Glands: EXOCRINE GLANDS ENDOCRINE GLANDS They pour their secretions directly into the blood They pour their secretions into ducts. Examples are ovaries and testes Examples are salivary and sweat glands.
DIFFERENCES BETWEEN THE NERVOUS SYSTEM AND ENDOCRINE SYSTEM: Both the nervous system and endocrine system is involved in co-ordination. Co-ordination refers to the linking together of all activities of the body for effective and harmonious functioning of the organism as a whole. We already know about the nervous system.
DIFFERENCES BETWEEN THE NERVOUS SYSTEM AND ENDOCRINE SYSTEM: The endocrine system brings about co-ordination using hormones. Both the nervous system and endocrine system work togetherto bring about co- ordination. However there many differences between these 2 systems. These differences are as follows:
DIFFERENCES BETWEEN THE NERVOUS SYSTEM AND ENDOCRINE SYSTEM: The differences between the nervous system and endocrine system. NERVOUS SYSTEM ENDOCRINE SYSTEM Messages are carried as nerve impulses Nerve impulses are very fast Messages are carried by hormones Messages travels very slowly Messages are carried along nerves Messages are carried by blood Acts for a very short time Acts for a long time Targets a very specific area Causes a brief or immediate reaction Acts over a wide area Results in along term reaction.
TERMINOLOGY: TERM: Co-ordination DEFINITION: USE IN SENTENCE: refers to the linking together of all activities of the body for effective and harmonious functioning of the organism as a whole. Endocrine system brings about co-ordination using hormones.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: The diagram alongside shows the endocrine glands in the human body. These glands are the: Hypothalamus Pituitary glands Thyroid gland Adrenal gland Pancreas Ovaries Testes 1. 2. 3. 4. 5. 6. 7. Endocrine Glands of the Human Body
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Hypothalamus : 1. Location: It occurs on the underside of the brain. Functions: It produces the hormone ADH. ADH is the anti- diuretic hormone. Location of Hypothalamus
ENDOCRINE GLANDS AND THEIR FUNCTIONS: This hormone is secreted by the pituitary gland. Functions of the ADH: This hormone controls the permeability of the renal tubules in the kidney. An increase in the levels of ADH increases the permeability of the renal tubules. Location of Pituitary Gland
ENDOCRINE GLANDS AND THEIR FUNCTIONS: A decrease in the secretion of ADH decreases the permeability of the renal tubules. It will work in the following way If the body loses too much water The pituitary gland secretes moreADH. 1. This increases thepermeabilityof the distal tubules and collecting ducts. 2.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Therefore more water leaves the tubules and enters the medulla. From the medulla the water is reabsorbed by the blood capillaries. 3. 4. In this way water is saved.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: If the body has too much water The pituitary gland decreasesthe secretion of ADH. This decreases the permeability of the distal convoluted tubule and collecting ducts. Therefore water cannot leave the tubules. 4. More water will leave the body with the urine. In this way excess water is lost. 1. 2. 3. 5.
TERMINOLOGY: TERM: ADH DEFINITION: USE IN SENTENCE: Refers to the anti- diuretic hormone. The ADH plays a role in maintaining the water balance of the body by increasing or decreasing the permeability of the renal tubules.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: The Pituitary Gland: This is a small pea- sized gland. 2. Location: This gland is found in a bony cavity at the base of the brain. It is attached to the hypothalamus of the brain. Location of Pituitary Gland
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Structure: It is a small pea sized gland. It is made up of 2 lobes. These are the anterior and posterior lobe. Both lobes produce hormones. Some of these hormones control other glands. Therefore the pituitary gland is also called the master gland. 2 lobes of the Pituitary Gland
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Functions: The hormones secreted by the anterior lobe of the pituitary gland are Growth hormone Thyroid stimulating hormone Follicle stimulating hormone Luteinizing hormone Prolactin 1. 2. 3. 4. 5. The posterior lobe secretes the hormone ADH.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: The Growth Hormone: 1. This hormone is responsible for the growth and development of the skeletal muscles. Sometimes too much or too little of this hormone is secreted. This results in the following conditions:
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Gigantism: This occurs during childhood. It is caused by an over-secretion of the growth hormone. This causes the muscles and bones to grow very quickly. a) The child will grow into a giant. Dwarfism: This condition also occurs in childhood. b)
ENDOCRINE GLANDS AND THEIR FUNCTIONS: In this case there is an under-secretion of the hormone. Which results in very slow growth of the bones and muscles. There is no effect on the mental development. Therefore the child develops into a very small adult. Acromegaly: This condition occurs in adults. It results from an over secretion of the hormone. c)
ENDOCRINE GLANDS AND THEIR FUNCTIONS: It results in the bones of the hands, legs and chin becoming enlarged. However under secretion of the growth hormone in an adult has little or no effect.
TERMINOLOGY: TERM: Gigantism DEFINITION: USE IN SENTENCE: Disease that occur in childhood because of an over-secretion of the growth hormone. Children with gigantism grow very quickly.
TERMINOLOGY: TERM: Dwarfism DEFINITION: USE IN SENTENCE: A condition that occurs in childhood because of an under-secretion of the growth hormone. Dwarfism results in very slow growth.
TERMINOLOGY: TERM: Acromegaly: DEFINITION: USE IN SENTENCE: Refers to a condition in adults that results from an over-secretion of the growth hormone. Adults who suffer from acromegaly usually have large bones in the hand and toes.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: The Thyroid Stimulating Hormone (TSH) 2. This hormone stimulates the thyroid gland to secrete the hormone thyroxin. If more TSH is secreted then the thyroid gland will secrete more thyroxin. If less TSH is secreted the thyroid gland will secrete less thyroxin.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: The Follicle Stimulating Hormone (FSH): 3. This hormone is secreted in both males and females. In females its function is to control the production of the egg in the ovary. The levels of FSH is the highest in the female body during ovulation. In males it controls the development of the sperms.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Luteinising Hormones (LH): 4. It is secreted by females. It has the following functions Controls the release of the egg during ovulation. Results in the conversion of the Graafian follicle into the corpus luteum after ovulation. Stimulates the Graafian follicles to produce oestrogen. a) b) c)
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Prolactin: 5. This hormone stimulates the production of milk. The process of milk production is called lactation.
TERMINOLOGY: TERM: Lactation DEFINITION: USE IN SENTENCE: Refers to the process of milk production by the mother. The hormone prolactin is responsible for lactation.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: The Thyroid Gland: 3. Location: This gland is found just below the larynx on either side of the trachea. Structure: It is an H-shaped gland. It is made up of 2 lobes. Location of Thyroid Gland
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Functions: This gland secretes the hormone thyroxin. The gland is stimulated to secrete thyroxin when the hormone TSH is secreted. Functions of Thyroxin: It regulates metabolic rate. It affects growth and functioning of the heart and nervous system. 1. 2.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Disorders associated with the gland and its secretion: Iodine is necessary for the production of thyroxin. If the levels of iodine is too low, then the thyroid gland swells. This is known as goitre. Goitre
ENDOCRINE GLANDS AND THEIR FUNCTIONS: If the thyroid gland secretes too little or too much thyroxin then the person suffers from Hypothyroidism or Hyperthyroidism 1. 2. Now lets look at each one. Hypothyroidism 1. This occurs when too little thyroxin is secreted. This results in a low metabolic rate.
ENDOCRINE GLANDS AND THEIR FUNCTIONS: In children the low production ((hypothyroidism) of thyroxin results in a condition called cretinism. Cretinism has the following symptoms Low metabolic rate which results in slow skeletal muscle development. The child becomes a dwarf. Slow mental development. The skin becomes thick and dry. The tongue becomes enlarged and sticks out of the mouth. a) b) c) d) e)
ENDOCRINE GLANDS AND THEIR FUNCTIONS: In adults the reduced secretion of thyroxin results in the condition known as myxoedema. Myxoedema has the following symptoms Memory loss Slowness of thought, speech and movement. The skin becomes thick and dry Increase in body mass. a) b) c) d)
ENDOCRINE GLANDS AND THEIR FUNCTIONS: Hyperthyroidism: 2. Hyperthyroidismrefers to the over- secretion of thyroxin. Symptoms: Increased metabolic rate. This leads to hyperactivity and nervous tension. Sticking out (protrusion) of the eyes, this is a different type of goitre. a) b) c)
SOMETHING EXTRA: In life science the prefix hypo means low. Associate the o in hypo with the o in low. The prefix hyper means high.
TERMINOLOGY: TERM: Thyroxin DEFINITION: USE IN SENTENCE: is the hormone secreted by the thyroid gland. TSH stimulates the thyroid gland to secrete the hormone thyroxin.
TERMINOLOGY: TERM: Iodine DEFINITION: USE IN SENTENCE: Is the nutrient that is required for the production of thyroxin. Any change in the levels of iodine would affect the production of thyroxin.
TERMINOLOGY: TERM: Goitre DEFINITION: USE IN SENTENCE: Is a condition that results from a deficiency of iodine. One of the symptoms of goitre is an enlarged thyroid gland.
TERMINOLOGY: TERM: Hypothyroidism DEFINITION: USE IN SENTENCE: Is caused when there is an under-secretion of thyroxin One symptom of hypothyroidism is a low metabolic rate
