The Endocrine System The Endocrine System (Chap 39, Sections 1 & 2)(Chap 39, Sections 1 & 2)

Maintaining HomeostasisMaintaining Homeostasis

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Introduction: What happens at Introduction: What happens at puberty?puberty?

The hypothalamus releases a chemical The hypothalamus releases a chemical called GnRH.called GnRH.GnRH stimulates the pituitary gland to GnRH stimulates the pituitary gland to release two more hormones:release two more hormones:– luteinizing hormone (LH for short) luteinizing hormone (LH for short) – follicle-stimulating hormone (FSH for follicle-stimulating hormone (FSH for

short) short) Girls and boys have both of these Girls and boys have both of these hormones. The hormones act in different hormones. The hormones act in different ways depending on what sex you are.ways depending on what sex you are.Girls usually start puberty 8 – 13.Girls usually start puberty 8 – 13.Boys usually start puberty 10 – 15.Boys usually start puberty 10 – 15.

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BoysBoys

These hormones travel through the blood These hormones travel through the blood & give the testes the signal to begin & give the testes the signal to begin production of sperm & testosterone. (need production of sperm & testosterone. (need sperm to reproduce)sperm to reproduce)

Get taller last 2 -3 years, can grow up to Get taller last 2 -3 years, can grow up to 4inches in a year.4inches in a year.

Gain weightGain weight

Shoulders get wider, body become more Shoulders get wider, body become more muscular.muscular.

Voices get deeper.Voices get deeper.

Grow hair under arms, pubic areas, & Grow hair under arms, pubic areas, & face.face.

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GirlsGirlsGain weight – this is NORMAL!Gain weight – this is NORMAL!

Girls' bodies usually become Girls' bodies usually become curvier curvier

They gain weight on their hips They gain weight on their hips

Breasts develop Breasts develop

Menstrual cycle beginsMenstrual cycle begins

Grow hair under arms & in pubic Grow hair under arms & in pubic areasareas

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The Endocrine SystemThe Endocrine SystemI.I. Function: Maintains homeostasis using Function: Maintains homeostasis using

hormones.hormones.1.1. An endocrine (ductless) gland An endocrine (ductless) gland

secretes its products (hormones) secretes its products (hormones) directly into the blood stream.directly into the blood stream.

2.2. Hormones are slow working but long Hormones are slow working but long lasting. lasting.

3.3. Hormones can only effect specific Hormones can only effect specific target cells. target cells.

What do we call glands that release What do we call glands that release their products through ducts to the their products through ducts to the outside of the body or into body outside of the body or into body cavities?cavities?

Exocrine glands Exocrine glands Examples: Sweat, Examples: Sweat, tears, & digestive juicestears, & digestive juices 55

Hypothalamus

Pituitary gland

Parathyroid glands

Thymus

Adrenal glands

Thyroid

Pancreas

Ovary

Testis

Endocrine Gland Locations (Fig. 39-2)

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II. Endocrine Gland Types & FunctionsII. Endocrine Gland Types & FunctionsA. PituitaryA. Pituitary – Secretes 9 hormones that – Secretes 9 hormones that

directly regulate many body directly regulate many body functions, & controls the actions of functions, & controls the actions of several other endocrine glands.several other endocrine glands.

** The pituitary gland is controlled by ** The pituitary gland is controlled by the the hypothalamushypothalamus

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Gigantism – an excess of growth hormone

Too much GHDuring childhoodDevelopment.

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Pituitary Dwarfism – Too little growth hormone

Too little GHDuring childhoodDevelopment.

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B.B. Hypothalamus Hypothalamus – Produces hormones – Produces hormones that control the pituitary gland, & that control the pituitary gland, & makes hormones stored in the makes hormones stored in the pituitary gland.pituitary gland.

C.C. ParathyroidParathyroid – Releases parathyroid – Releases parathyroid hormone which acts to maintain hormone which acts to maintain homeostasis of the calcium levels in homeostasis of the calcium levels in the blood and bones.the blood and bones.

D.D. Thymus Thymus – During childhood stimulates – During childhood stimulates T cell development & proper immune T cell development & proper immune response.response.

E.E. AdrenalAdrenal – Release epinephrine & – Release epinephrine & norepinephrine which help the body norepinephrine which help the body respond to stress (flight or fight respond to stress (flight or fight response).response).

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F.F. ThyroidThyroid – Regulates the bodies – Regulates the bodies metabolism by producing thyroxine metabolism by producing thyroxine (increases the rate of protein, (increases the rate of protein, carbohydrate & fat metabolism & also carbohydrate & fat metabolism & also cellular respiration).cellular respiration).

G.G. PancreasPancreas – produces insulin & glucagon – produces insulin & glucagon which regulate the level of glucose in which regulate the level of glucose in the blood. the blood. Signals liver to store or Signals liver to store or release glucose.release glucose.

H.H. OvaryOvary – produces estrogen and – produces estrogen and progesterone. These produce primary progesterone. These produce primary and secondary sex characteristics and and secondary sex characteristics and regulate the menstrual cycle and regulate the menstrual cycle and pregnancy.pregnancy.

I.I. TestisTestis – produces testosterone for – produces testosterone for sperm production and primary and sperm production and primary and secondary sex characteristics.secondary sex characteristics.

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III. How do hormones work?III. How do hormones work?A.A. Hormones belong to two groups – Hormones belong to two groups –

steroid hormones & non-steroid steroid hormones & non-steroid hormones.hormones.

B. Steroid hormones B. Steroid hormones 1. 1. Made of lipids Made of lipids (fats) & (fats) & can can cross cell membranescross cell membranes directly into directly into the cytoplasm and nucleus.the cytoplasm and nucleus.2. Binds to a receptor protein 2. Binds to a receptor protein

insideinside the cell. the cell.3. This receptor activates genes 3. This receptor activates genes

that carry out the actions that carry out the actions associated with the hormone.associated with the hormone. 1212

C. Nonsteroid hormones – Cannot pass C. Nonsteroid hormones – Cannot pass through the cell membrane.through the cell membrane.

1.1.Made of proteins Made of proteins & bind to & bind to receptors receptors on the cell membrane on the cell membrane surfacesurface..

2. This activates an enzyme on the 2. This activates an enzyme on the inner surface inner surface of the cell membrane.of the cell membrane.

3. The enzyme activates secondary 3. The enzyme activates secondary messengers to carry the signalmessengers to carry the signal

4. The second messenger activates or 4. The second messenger activates or inhibits cell activities.inhibits cell activities.

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Steroid Hormone

Target cell membrane

mRNA

Cytoplasm

Protein synthesis

Altered cellular function

Receptor

Hormone-receptor complex

Nucleus

DNA

Nonsteroid hormone (first messenger)

Receptor Target cell membrane

cAMP (second messenger)

Enzyme activities

Altered cellular function

Cytoplasm

Nucleus

Steroid & Nonsteroid Hormones (fig. 39-3)

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An Example of Endocrine Controlled Homeostasis

Regulation of blood sugar levels

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Room temperature increases

Thermostat senses temperature change and switches on heating system

Thermostat senses temperature change and switches off heating system

Room temperature decreases

Negative Feedback Example of Homeostasis (Fig. 35-4, p.895)

IV.Negative feedback – your body’s response results in decreasing the effect of the stimulus, (e.g. body temperature). The effect is a relatively steady state is maintained.

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regulates

Concept MapConcept Map

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

by meansof the

GrowthWater

balanceReproduction Metabolism

Calciumand glucose

levels

Responseto stress

The Endocrine System

Pituitary

Ovaries

Testes Thyroid Pancreas Adrenals

Parathyroids

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PMS SymptomsPMS SymptomsCause Unknown: 70 – 80% experience these Cause Unknown: 70 – 80% experience these

symptomssymptoms

Weight gainWeight gainBreast swellingBreast swellingWater retentionWater retentionBackacheBackacheCramps!!!Cramps!!!AcneAcneFatigueFatigueDiarrhea, constipation, nauseaDiarrhea, constipation, nauseaInsomnia, headache, loneliness Insomnia, headache, loneliness

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The Endocrine System