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CHAPTER 15 Hormones.

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Presentation on theme: "CHAPTER 15 Hormones."— Presentation transcript:

1 CHAPTER 15 Hormones

2 Chapter 15 Hormones 15.1 What are Hormones? 15.2 Endocrine Glands and their Hormonal Secretions 15.3 Effects of Some Hormones 15.4 Comparing Endocrine and Nervous Controls

3 15.1 What are Hormones? Learning Outcome
After this section, you should be able to: Describe the role of hormones and endocrine glands.

4 15.1 What are Hormones? What are hormones?
Hormones are chemical substances produced in minute quantities by endocrine glands. They are transported by blood to target organs. They influence growth, development and activity of an organism. After performing their functions, they are destroyed in the liver and excreted by the kidneys.

5 How do hormones affect the body?
15.1 What are Hormones? How do hormones affect the body? Help in the delivery of baby out of the mother’s womb during childbirth Result in the increase in height of a child Prepare the body for ‘fight’ or ‘flight’ during dangerous encounters Responsible for physical and emotional changes during puberty

6 How do hormones affect the body?
15.1 What are Hormones? How do hormones affect the body? Production of hormones must be carefully controlled. When too much or too little hormones are produced, the organism will be adversely affected. For example: Too little thyroxine in a tadpole will inhibit its grow into a frog. Too much thyroxine turn tadpole into the adult form too quickly, resulting in a tiny frog.

7 How is the production of hormones controlled?
15.1 What are Hormones? How is the production of hormones controlled? Hormone production in the body is controlled by: the nervous system certain chemical substances (hormones from other endocrine glands) Production of hormone in the adrenal gland is controlled by the nervous system. The hormonal and nervous system work together to coordinate and control secretion of hormones in the body.

8 Where are hormones produced?
15.1 What are Hormones? Where are hormones produced? In endocrine glands where they are released directly into the blood Such glands have an extensive network of blood vessels to transport hormones to their target organs. Hormones travel in blood to reach target organs. endocrine gland

9 15.1 What are Hormones? Types of glands Endocrine glands
Exocrine glands Ductless glands that transport their secretions via the bloodstream Examples: adrenal glands, pituitary gland, and pancreas Ducts present to transport secretions to target organs Examples: sweat glands, salivary glands and pancreas Note: The pancreas is a special gland that produces hormones and enzymes. Insulin and glucagon (hormones) are secreted directly into the bloodstream by a special group of cells called the islets of Langerhans while pancreatic juice is transported via the pancreatic duct to the duodenum.

10 Chapter 15 Hormones 15.1 What are Hormones? 15.2 Endocrine Glands and their Hormonal Secretions 15.3 Effects of Some Hormones 15.4 Comparing Endocrine and Nervous Controls

11 Endocrine Glands and their Hormonal Secretions 15.2
Learning Outcome After this section, you should be able to: State the location and functions of the endocrine glands; pituitary gland, thyroid gland, adrenal glands, pancreas and the gonads.

12 Endocrine Glands and their Hormonal Secretions 15.2
Endocrine glands in the body Pituitary gland Controls the functions of several other endocrine glands Secretes many hormones: Growth hormone (GH) Antidiuretic hormone (ADH) Thyroid-stimulating hormone (TSH) Some hormones control other endocrine glands e.g. TSH The hypothalamus regulates the secretion of some pituitary hormones. Hypothalamus Below are the functions of the hormones mentioned above. Growth hormone – stimulates growth of all parts of the body Antidiuretic hormone – promotes water reabsorption from kidney tubules Thyroid-stimulating hormone – stimulates secretions of the thyroid gland Note: Pituitary gland is also known as the ‘master gland’.

13 Endocrine Glands and their Hormonal Secretions 15.2
Endocrine glands in the body Adrenal glands Situated on top of each kidney When stimulated by the nervous system, the hormone adrenaline is released. Note: Effects of the hormone adrenaline will be discussed in detail in the next section (15.3 Effects of Various Hormones).

14 Endocrine Glands and their Hormonal Secretions 15.2
Endocrine glands in the body Pancreas Has both endocrine and exocrine functions Exocrine gland - secretes pancreatic juice via pancreatic ducts Endocrine - Islet of Langerhans secrete insulin and glucagon to control blood glucose levels

15 Endocrine Glands and their Hormonal Secretions 15.2
Endocrine glands in the body Gonads Ovaries (in females) secrete oestrogen and progesterone. Oestrogen controls the development of breasts and broadening of the pelvis. Progesterone helps maintain a healthy pregnancy. Note: Hormones released by the gonads controls the development of primary and secondary sexual characteristics.

16 Endocrine Glands and their Hormonal Secretions 15.2
Endocrine glands in the body Gonads Testes (in males) secrete testosterone. Testosterone causes deepening of voice and growth of facial hair. Note: Hormones released by the gonads controls the development of primary and secondary sexual characteristics.

17 Endocrine Glands and their Hormonal Secretions 15.2
A summary on endocrine glands in the body Hypothalamus Regulates the secretion of some pituitary hormones Pituitary gland Secretes hormones that control other endocrine glands Pancreas Secretes insulin and glucagon Adrenal glands Secrete adrenaline Ovaries Secrete oestrogen and progesterone Testes Secrete testosterone

18 Chapter 15 Hormones 15.1 What are Hormones? 15.2 Endocrine Glands and their Hormonal Secretions 15.3 Effects of Some Hormones 15.4 Comparing Endocrine and Nervous Controls

19 Effects of Some Hormones
15.3 Effects of Some Hormones Learning Outcome After this section, you should be able to: Describe the role of hormones insulin, glucagon and adrenaline.

20 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of insulin Insulin hormone decreases blood sugar concentration. Increases the rate of glucose uptake by cells By making cell membranes more permeable to glucose

21 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of insulin Stimulates the liver and muscle cells to convert glucose into glycogen for storage Increases the oxidation of glucose during tissue respiration excess glucose  glycogen liver oxygen glucose water carbon dioxide

22 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of insulin (over-secretion) Over-secretion of insulin results in abnormally low blood glucose concentration. Symptoms includes hunger, rapid heartbeat and irritability In severe cases, person may lapse into a coma or even die

23 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of insulin (lack of insulin secretion) Lack of insulin secretion results in abnormally high blood glucose concentration. Tissue cells cannot utilise or store glucose Symptoms includes weak body, continual weight loss and glucose present in urine Could lead to diabetes mellitus disease

24 Effects of Some Hormones
15.3 Effects of Some Hormones What is diabetes mellitus? Insufficient insulin secretion to regulate blood glucose concentration Leads to persistently high level of glucose in blood Kidneys are unable to completely reabsorb glucose in body Causing glucose to be excreted in urine

25 Effects of Some Hormones
15.3 Effects of Some Hormones What are the signs of diabetes mellitus? Constantly high blood glucose concentration Presence of glucose in urine after a meal Healing of wounds is slow and difficult

26 Type I diabetes Type II diabetes
15.3 Effects of Some Hormones URL Types of diabetes Type I diabetes Type II diabetes Early-onset diabetes Late-onset diabetes Insufficient or no insulin production Insulin is produced but target cells do not respond well to insulin Note: Type I diabetes develops early in a person’s life hence is known as early-onset while type II diabetes develops later in a person’s life hence is known as late-onset diabetes. Overweight people are at greater risk of developing type II diabetes. Treatment is by insulin injection Treatment is by control of dietary intake and exercising

27 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of glucagon Glucagon increases the blood glucose concentration. It stimulates the following conversions: Glycogen into glucose Fats and amino acids into glucose Lactic acid into glucose Note: Lactic acid is produced from anaerobic respiration. It is important to remove lactic acid from the body system as they are harmful to the body when present in large amount for extended period of time.

28 Increase in blood glucose concentration
15.3 Effects of Some Hormones Effects of glucagon Main target organ of glucagon is the liver. Low blood glucose concentration Islets of Langerhans secrete glucagon More glucose is produced Increase in blood glucose concentration

29 Effects of Some Hormones
15.3 Effects of Some Hormones Secretion of insulin and glucagon are controlled by negative feedback mechanisms Note: Insulin and glucagon are antagonistic hormones. Insulin and glucagon work together in regulating the blood glucose level. This is a homeostatic mechanism.

30 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of adrenaline URL Adrenaline is secreted in response to stress or excitement. It allows the body to respond quickly to sudden demands for energy. The effects of adrenaline are usually short-lived. adrenal gland kidney Click on the Video-URL button to be directed to a website with a short video that describes the situation where adrenaline is secreted to prepare the body for running a race.

31 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of adrenaline 1 Stimuli activate sensory neurons in the hypothalamus sensory neurone nerve impulses spinal cord 2 Adrenal gland is stimulated to produce adrenaline Highlight that this situation involves both nervous and hormonal system. Adrenaline is secreted in response to stimuli detected by the nervous system. Note: Stimuli can be in the form of fear, anger, anxiety, stress, etc. adrenal gland 3 Adrenaline is carried in blood to target organs 4 Target organs response to the short-term effect of adrenaline

32 Effects of Some Hormones
15.3 Effects of Some Hormones Effects of adrenaline Increases blood pressure and rate of heartbeat Increases rate and depth of ventilation Increases metabolic rate Adrenaline Causes pupils to dilate Increases blood glucose level Increases the rate of blood coagulation Further explanations on the effects of adrenaline on the body: Blood glucose level is increased by speeding up the breakdown glycogen to glucose in the liver and muscles. Increase in metabolic rate means more energy is available for the body. Rate of heart beat and blood pressure are increased to ensure more oxygen is supplied to muscles. Rate of ventilation is increased by relaxing the bronchioles to increase air flow to lungs. Pupils dilate to allow more light to enter to enhance vision. The constriction of arterioles in skin helps to channel more blood to the muscles. Contracts hair muscles, producing ‘goose pimples’ Constricts arterioles in skin

33 Chapter 15 Hormones 15.1 What are Hormones? 15.2 Endocrine Glands and their Hormonal Secretions 15.3 Effects of Some Hormones 15.4 Comparing Endocrine and Nervous Controls

34 Comparing Endocrine and Nervous Controls 15.4
Learning Outcome After this section, you should be able to: List the similarities and differences between endocrine and nervous controls.

35 Comparing Endocrine and Nervous Controls 15.4
Similarities between Endocrine and Nervous Controls Both have the following components: A detector that detects a stimulus A signal or message that is transmitted An effector (target organ that carries out the response)

36 15.4 Comparing Endocrine and Nervous Controls
Differences between Endocrine and Nervous Controls Nervous control Endocrine control Involves neurons Involves hormones Electrical and chemical transmission Chemical transmission Nerve impulses are transmitted by neurones Hormones are transmitted by the blood Rapid transmission and response Slower transmission and relatively slow-acting Often causes short-term effects Can cause long-term or short-term effects Voluntary or involuntary Always involuntary Usually localised response Usually widespread effects

37 Chapter 15 Hormones

38 Chapter 15 Hormones The URLs are valid as at 15 October 2012.

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