1. The Endocrine System

2. Endocrine system Made of glands and their products Made of glands and their products Release products into the blood to deliver messages to different parts of the body Release products into the blood to deliver messages to different parts of the body

3. To return to the chapter summary click escape or close this document. Gland Function Chart

4. Hormones Chemicals released in one part of the body that travel through the bloodstream to affect other areas of the body Chemicals released in one part of the body that travel through the bloodstream to affect other areas of the body Bind to specific receptors on target cells Bind to specific receptors on target cells Full effect of hormones may take minutes, hours, or days Full effect of hormones may take minutes, hours, or days

5. Glands Exocrine glands release their products through ducts directly to organs that use them; include glands that release sweat, tears, and digestive juices Exocrine glands release their products through ducts directly to organs that use them; include glands that release sweat, tears, and digestive juices Endocrine glands release their secretions into the bloodstream Endocrine glands release their secretions into the bloodstream

6. 2 groups of hormones Steroid hormones-are produced from a lipid called cholesterol Steroid hormones-are produced from a lipid called cholesterol Nonsteroid hormones-include proteins, small peptides, and amino acids Nonsteroid hormones-include proteins, small peptides, and amino acids

7. Steroid hormones Can cross cell membranes easily, passing directly across the lipid bilayer into the cytoplasm or the nucleus Can cross cell membranes easily, passing directly across the lipid bilayer into the cytoplasm or the nucleus Binds a receptor-protein to make a hormone- receptor complex Binds a receptor-protein to make a hormone- receptor complex Complex enters the nucleus and binds to DNA Complex enters the nucleus and binds to DNA Binding DNA initiates transcription of specific genes to mRNA Binding DNA initiates transcription of specific genes to mRNA mRNA moves to cytoplasm for translation into proteins mRNA moves to cytoplasm for translation into proteins

8. Steroid hormones Hormone-receptor complexes regulate gene expression Hormone-receptor complexes regulate gene expression They can “turn on” or “turn off” whole sets of genes They can “turn on” or “turn off” whole sets of genes Can produce dramatic changes in cell and organism activity Can produce dramatic changes in cell and organism activity

9. Nonsteroid hormones Cannot pass through the cell membrane Cannot pass through the cell membrane Must bind a receptor on the outside of the cell membrane Must bind a receptor on the outside of the cell membrane Binding the receptor activates an enzyme on the inside of the membrane Binding the receptor activates an enzyme on the inside of the membrane Enzyme activates secondary messengers (Ca 2+ ions, cAMP, nucleotides, fatty acids) and carry the message to the inside of the cell Enzyme activates secondary messengers (Ca 2+ ions, cAMP, nucleotides, fatty acids) and carry the message to the inside of the cell Second messengers can alter other cell activities Second messengers can alter other cell activities

10. Prostaglandins Modified fatty acids Modified fatty acids Affect only nearby cells and tissues Affect only nearby cells and tissues Cause smooth muscles to contract, such as those in uterus, bronchioles, and blood vessels Cause smooth muscles to contract, such as those in uterus, bronchioles, and blood vessels Causes sensation of pain in most headaches Causes sensation of pain in most headaches

11. Controlling metabolism Metabolic activities are controlled by the levels of thyroxine Metabolic activities are controlled by the levels of thyroxine Thyroxin is released by the thyroid gland Thyroxin is released by the thyroid gland Thyroid gland is controlled by the hypothalamus and anterior pituitary gland Thyroid gland is controlled by the hypothalamus and anterior pituitary gland Hypothalamus senses a low level of thyroxine in blood, it secretes thyroid- releasing hormone (TRH) Hypothalamus senses a low level of thyroxine in blood, it secretes thyroid- releasing hormone (TRH)

12. Controlling metabolism cont TRH stimulates anterior pituitary to secrete thyroid-stimulating hormone (TSH) TRH stimulates anterior pituitary to secrete thyroid-stimulating hormone (TSH) TSH stimulates the release of thyroxine by the thyroid gland TSH stimulates the release of thyroxine by the thyroid gland High levels of thyroxine in the blood inhibit the secretion of TRH and TSH and stops additional release of thyroxine High levels of thyroxine in the blood inhibit the secretion of TRH and TSH and stops additional release of thyroxine

13. Body temperature Also controlled by hypothalamus Also controlled by hypothalamus Since increased metabolic rates raise body temperature Since increased metabolic rates raise body temperature If low body temperature is sensed by the hypothalamus, TRH and TSH will be released to stimulate release of thyroxine If low body temperature is sensed by the hypothalamus, TRH and TSH will be released to stimulate release of thyroxine Thyroxin increases metabolism and thus increases or raises body temperature Thyroxin increases metabolism and thus increases or raises body temperature

14. Maintaining water balance Hypothalamus is sensitive to water levels in the blood Hypothalamus is sensitive to water levels in the blood Loss of water raises the concentration of dissolved materials in blood and signals the hypothalamus to stimulate the pituitary to release ADH (antidiuretic hormone) Loss of water raises the concentration of dissolved materials in blood and signals the hypothalamus to stimulate the pituitary to release ADH (antidiuretic hormone) ADH travels to kidneys to slow down removal of water and triggers sensation of thirst ADH travels to kidneys to slow down removal of water and triggers sensation of thirst

15. Water balance cont Water is quickly absorbed when consumed Water is quickly absorbed when consumed When water levels in blood increase, the pituitary releases LESS ADH so the kidneys can remove more water When water levels in blood increase, the pituitary releases LESS ADH so the kidneys can remove more water This restores the blood to its normal concentration This restores the blood to its normal concentration

16. Sleep cycle Controlled through the pineal gland by influencing the pituitary gland and producing the hormone melatonin Controlled through the pineal gland by influencing the pituitary gland and producing the hormone melatonin Pineal gland’s functioning is initiated by the amount of light in a 24 hour period Pineal gland’s functioning is initiated by the amount of light in a 24 hour period

17. Complimentary hormone action Used to regulate calcium levels in the bloodstream Used to regulate calcium levels in the bloodstream Blood Ca 2+ levels get too high, thyroid gland releases calcitonin so kidneys reabsorb less calcium, less calcium is absorbed in intestines and MORE calcium is deposited in bones Blood Ca 2+ levels get too high, thyroid gland releases calcitonin so kidneys reabsorb less calcium, less calcium is absorbed in intestines and MORE calcium is deposited in bones Blood Ca 2+ levels get too low, parathyroid hormone (PTH) is released from parathyroid glands so kidneys reabsorb more Ca 2+, intestines absorb more Ca 2+, and bones release Ca 2+ into blood Blood Ca 2+ levels get too low, parathyroid hormone (PTH) is released from parathyroid glands so kidneys reabsorb more Ca 2+, intestines absorb more Ca 2+, and bones release Ca 2+ into blood

18. To return to the chapter summary click escape or close this document. PTH Hormones Diagram

19. Importance of Calcium If calcium levels in blood drop below a normal range: If calcium levels in blood drop below a normal range: Blood doesn’t clot Blood doesn’t clot Muscles don’t contract Muscles don’t contract Transport of materials across cell membranes will fail Transport of materials across cell membranes will fail

20. Pituitary gland Is divided into two parts: anterior pituitary and posterior pituitary Is divided into two parts: anterior pituitary and posterior pituitary Secretes 9 hormones that directly regulate body functions and controls actions of other endocrine glands Secretes 9 hormones that directly regulate body functions and controls actions of other endocrine glands

21. Posterior pituitary Antidiuretic hormone (ADH)-stimulates kidneys to reabsorb water from collecting tubules Antidiuretic hormone (ADH)-stimulates kidneys to reabsorb water from collecting tubules Oxytocin-stimulates contractions of uterus during birth; releases milk in nursing mothers Oxytocin-stimulates contractions of uterus during birth; releases milk in nursing mothers

22. Posterior pituitary Follicle-stimulating hormone (FSH)- stimulates production of mature eggs and sperm Follicle-stimulating hormone (FSH)- stimulates production of mature eggs and sperm Luteinizing hormone (LH)-stimulates ovaries and testes; prepares uterus for implantation of fertilized egg Luteinizing hormone (LH)-stimulates ovaries and testes; prepares uterus for implantation of fertilized egg Thyroid-stimulating hormone (TSH)- stimulates the synthesis and release of thyroxine from the thyroid gland Thyroid-stimulating hormone (TSH)- stimulates the synthesis and release of thyroxine from the thyroid gland

23. Posterior pituitary cont. Adreno-corticotropic hormone (ACTH)-stimulates release of some hormones from the adrenal cortex, mainly cortisol (overproduction of which causes Cushing’s disease) Adreno-corticotropic hormone (ACTH)-stimulates release of some hormones from the adrenal cortex, mainly cortisol (overproduction of which causes Cushing’s disease) Growth hormone (GH)-stimulates protein synthesis and growth in cells Growth hormone (GH)-stimulates protein synthesis and growth in cells Prolactin-stimulates milk production in nursing mothers Prolactin-stimulates milk production in nursing mothers Melanocyte-stimulating hormone (MSH)- stimulates the melanocytes of the skin, increasing their production of the skin pigment melanin Melanocyte-stimulating hormone (MSH)- stimulates the melanocytes of the skin, increasing their production of the skin pigment melanin

24. To return to the chapter summary click escape or close this document. hGH Hormone diagram

25. Hypothalamus Controls secretions of pituitary gland Controls secretions of pituitary gland Influenced by hormone levels in the blood and sensory information received from nervous system Influenced by hormone levels in the blood and sensory information received from nervous system Posterior pituitary made of axons whose cell bodies are in the hypothalamus Posterior pituitary made of axons whose cell bodies are in the hypothalamus When cell bodies are stimulated, axons of posterior pituitary release their hormones When cell bodies are stimulated, axons of posterior pituitary release their hormones

26. Hypothalamus cont Indirect affect on anterior pituitary Indirect affect on anterior pituitary Hypothalamus produces releasing hormones in the blood that are carried to anterior pituitary to control production and release of hormones Hypothalamus produces releasing hormones in the blood that are carried to anterior pituitary to control production and release of hormones

27. Thyroid gland Major role in regulating metabolism Major role in regulating metabolism Produces thyroxine to increase the rate of protein, carbohydrate, and fat metabolism Produces thyroxine to increase the rate of protein, carbohydrate, and fat metabolism Thyroxine also increases rate of cellular respiration and the amount of energy and heat released Thyroxine also increases rate of cellular respiration and the amount of energy and heat released Decreased levels of thyroxine decrease the rate of cellular respiration and the amount of energy and heat released Decreased levels of thyroxine decrease the rate of cellular respiration and the amount of energy and heat released

28. Hyperthyroidism Caused by too much thyroxine Caused by too much thyroxine Results in nervousness, elevated body temperature, increased metabolic rate, increased blood pressure, and weight loss Results in nervousness, elevated body temperature, increased metabolic rate, increased blood pressure, and weight loss

29. Hypothyroidism Caused by too little thyroxine Caused by too little thyroxine Results in lower metabolic rates, lower body temperature, lack of energy, and weight gain Results in lower metabolic rates, lower body temperature, lack of energy, and weight gain Can cause a goiter (enlargement of the thyroid gland) Can cause a goiter (enlargement of the thyroid gland)

30. Parathyroid glands Four Four Help control calcium levels in blood Help control calcium levels in blood Promote proper nerve and muscle function and bone structure Promote proper nerve and muscle function and bone structure

31. Adrenal glands Located on top of kidneys Located on top of kidneys Release hormones that help body prepare for and deal with stress Release hormones that help body prepare for and deal with stress Outer part is adrenal cortex; inner part is adrenal medulla Outer part is adrenal cortex; inner part is adrenal medulla

32. Adrenal cortex 80% of adrenal gland 80% of adrenal gland Produces over 24 corticosteroid hormones Produces over 24 corticosteroid hormones Aldosterone-regulates reabsorption of sodium ions and excretion of potassium ions by kidneys Aldosterone-regulates reabsorption of sodium ions and excretion of potassium ions by kidneys Cortisol-helps control rate of metabolism of carbohydrates, fats, and proteins Cortisol-helps control rate of metabolism of carbohydrates, fats, and proteins Over-production of cortisol can lead to Cushing’s disease Over-production of cortisol can lead to Cushing’s disease

33. Adrenal medulla Regulated by sympathetic nervous system Regulated by sympathetic nervous system Prepares body for energy-intense activities Prepares body for energy-intense activities Epinephrine (80% of total secretions from adrenal medulla) and norepinephrine Epinephrine (80% of total secretions from adrenal medulla) and norepinephrine Fight or flight response Fight or flight response Increase heart rate, blood pressure, blood flow to muscles, open air passages, release extra glucose into blood, increases body activity Increase heart rate, blood pressure, blood flow to muscles, open air passages, release extra glucose into blood, increases body activity

34. Adrenal gland Also responsible for causing post- traumatic stress syndrome (PTSS) Also responsible for causing post- traumatic stress syndrome (PTSS) Release of some hormones from adrenal gland causes the person to re-experience a traumatic event Release of some hormones from adrenal gland causes the person to re-experience a traumatic event

35. Pancreas Acts as an exocrine gland by releasing secretions through ducts to intestine to help break down food Acts as an exocrine gland by releasing secretions through ducts to intestine to help break down food Acts as an endocrine gland by releasing hormones into the blood Acts as an endocrine gland by releasing hormones into the blood

36. Pancreas (endocrine function) Hormones released from islets of Langerhans Hormones released from islets of Langerhans Each islet has beta cells that release insulin and alpha cells that release glucagon Each islet has beta cells that release insulin and alpha cells that release glucagon Insulin stimulates liver and muscles to remove sugar from the blood and store it as glycogen or fat Insulin stimulates liver and muscles to remove sugar from the blood and store it as glycogen or fat Glucagon stimulates the liver to break down glycogen and release glucose back into the blood and the release of fatty acids from stored fats Glucagon stimulates the liver to break down glycogen and release glucose back into the blood and the release of fatty acids from stored fats

37. To return to the chapter summary click escape or close this document. Pancreas & Liver

38. Reproductive glands Gonads produce gametes and secrete sex hormones Gonads produce gametes and secrete sex hormones Female gonads are ovaries and produce eggs (ova) Female gonads are ovaries and produce eggs (ova) Male gonads are testes and produce sperm Male gonads are testes and produce sperm

39. Ovaries Estrogen-female sex hormone; required for development of eggs and formation of physical traits associated with female body Estrogen-female sex hormone; required for development of eggs and formation of physical traits associated with female body Progesterone-prepares uterus for arrival of developing embryo Progesterone-prepares uterus for arrival of developing embryo

40. Testes Produce testosterone Produce testosterone Required for normal sperm production Required for normal sperm production Development of physical traits associated with male body Development of physical traits associated with male body