The Endocrine System --the OTHER sensing and response system

The Endocrine System Controls:

The Endocrine System Controls: Reproduction Growth & development Homeostasis Metabolism Immune response

Definitions Gland Endocrine Hormone

Definitions Gland—an organ designed to secrete Endocrine—secreting inside the body Hormone—the secretion of an endocrine gland

Endocrine vs Exocrine

Exocrine glands have a duct Endocrine glands do not Endocrine glands secrete their products into the bloodstream

For example: Exocrine glands include… GlandDuct leads to: Sweat glands Sebaceous glands Pancreas Mammary glands

For example: Exocrine glands include… GlandDuct leads to: Sweat glands surface of skin Sebaceous glandsbase of follicle Pancreassmall intestine Mammary glandsnipple

For example: Endocrine glands include… GlandDuct leads to: Anterior pituitary Parathyroids Adrenal Cortex

For example: Endocrine glands include… GlandDuct leads to: Anterior pituitary --No duct-- Parathyroids--No duct-- Adrenal Cortex--No duct-- These glands secrete hormones directly to the bloodstream

Negative feedback Homeostasis is maintained in the body by negative feedback— When anything changes, the response is to undo that change The elements of the system are: stimulus, sensor, effector and response.

In general: Sensor Effector If the stimulus is too high If the stimulus is too low Response lowers it Response raises it

Review Body temperature is maintained by a negative feedback system. --The sensor is in the hypothalamus. --The effectors are blood vessels and sweat glands in the skin.

For body temperature: Hypo- thalamus Skin If the temperature is too high If the temperature is too low Blood vessels dilate, sweat is produced Blood vessels constrict, sweat is not produced

For blood sugar: Pancreas If the blood glucose level is too high If the blood glucose level is too low Insulin causes body cells to take in glucose Glucagon causes the liver to release glucose

For blood sugar: The sensor and effector cells are in the pancreas The pancreas releases insulin into the bloodstream to lower blood sugar or The pancreas releases glucagon into the bloodstream to raise blood sugar

Types of hormones

Peptide hormones Steroid hormones

Types of hormones Peptide hormones —proteins and related molecules Steroid hormones —lipid molecules

Types of hormones Peptide hormones —proteins and related molecules Receptors are on target cell surfaces Steroid hormones —lipid molecules Receptors are in target cell nuclei

Nonsteroid hormone (first messenger)

Figure 9.1b Cytoplasm Nonsteroid hormone (first messenger) Enzyme Receptor protein Second messenger Effect on cellular function, such as glycogen breakdown Plasma membrane of target cell ATP cAMP

Second-Messenger System (Non-steroid Hormone Action) A non-steroid hormone will: Bind to a membrane receptor (without entering cell) (Series of reactions)  activates an enzyme Enzyme catalyzes a reaction to form the second-messenger (us. cAMP) Second-messenger molecule  a specific response

Steroid hormone

Figure 9.1a Nucleus Cytoplasm Steroid hormone Receptor protein Hormone-receptor complex DNA mRNA New protein Plasma membrane of target cell

Direct Gene Activation (Steroid Hormone Action) A steroid hormone will: Diffuse through membrane of target cells Enter the nucleus Bind to a specific protein in the nucleus Bind to specific sites on the cell’s DNA Activate genes  synthesis of new proteins

Endocrine Glands Hypothalamus Anterior pituitary Posterior pituitary Thyroid Parathyroids Adrenal Medulla Adrenal Cortex Pancreas

Location of Endocrine Glands Hypothalamusin the brain Anterior pituitarybase of the brain Posterior pituitarybase of the brain Thyroidfront of the neck Parathyroidssides of the neck Adrenal Medullaabove the kidney Adrenal Cortexabove the kidney Pancreasbehind stomach

Location of Major Endrocrine Organs Figure 9.3

Hormones of each Endocrine Gland HypothalamusRF’s Anterior pituitaryACTH, FSH, GH,LH, PRL,TSH Posterior pituitaryADH, OT ThyroidCal,T3-4 ParathyroidsPTH Adrenal MedullaEPI, NE Adrenal CortexCor, Ald PancreasIns, Glu, SS

For example: Blood sugar Pancreas If the blood glucose level is too high If the blood glucose level is too low Insulin causes body cells to take in glucose Glucagon causes the liver to release glucose

For example: Metabolism Hypothalamus Ant. Pit. & Thyroid If the metabolism level is too high If the metabolism level is too low T3-4  Less Rf  Less TSH  less T3-4 RF  anterior pituitary. TSH causes the thyroid to make T3-4 to increase metabolism Ant. Pit. & Thyroid

Hypothalamus --Part of the brain --Closely associated with pituitary (blood vessel and nerve connection) --Makes releasing factors (RF’s) to affect pituitary

Hormones of the Anterior Pituitary Figure 9.4

Pituitary --Part of the brain, sits in the sella turcica --Controlled by hypothalamus, controls other glands --Has two (very different) parts- anterior and posterior

Anterior Pituitary --Controls other glands --ACTH  adrenal cortex --PRL  mammary glands --FSH  ovaries --LH  ovaries --GH is the only hormone with wider effects—causes growth of bone and muscle

For the reproductive system Ant. Pit Ovaries FSH and LH stimulate the ovary Progesterone and estrogen stimulate the hypothalamus to make RFs

Posterior pituitary --Direct nervous control from hypothalamus (Hormones are made in hypothalamus, stored for release) --OT-causes smooth muscle contraction in childbirth, nursing, erections, etc. --ADH—(next slide)

For water Hypothalamus Hyp/Post.Pit Post. Pit Too much water in the blood Too little water in the blood Shuts off ADH—kidneys reabsorb less water ADH causes kidneys to re- absorb more water

Thyroid --Controlled by TSH (from ant. pit.) Makes --T3-4— triiodothyronine and thyroxine, --stimulates most cells to use energy and make proteins (higher metabolism). --Contain iodine atoms. --Calcitonin (not quite the next slide)

Thyroid Gland Figure 9.7a

For metabolism: Hypothalamus Ant. Pit. & Thyroid If the metabolism level is too high If the metabolism level is too low T3-4  Less Rf  Less TSH  less T3-4 RF  anterior pituitary. TSH causes the thyroid to make T3-4 to increase metabolism Ant. Pit. & Thyroid

For calcium Thyroid/ Parathyroid Thyroid Parathyroid If the blood calcium level is too high If the blood calcium level is too low Calcitonin causes bones to store calcium Parathyroid hormone causes bones to release calcium, kidneys and intestines to absorb Ca ++

Parathyroids --Four of them! Near the thyroid --Makes PTH only (previous slide)— (antagonistic to calcitonin) —affects bones, kidneys and intestines to increase Ca ++ levels

Pancreas --Endocrine (islets of Langerhans) and exocrine (in digestive system) Makes— --glucagon in  (alpha) cells (next slide) --insulin in  (beta) cells (next slide) --somatostatin in  (delta) cells --antagonist to GH

For Blood Sugar: Pancreas If the blood glucose level is too high If the blood glucose level is too low Insulin causes body cells to take in glucose Glucagon causes the liver to release glucose

Adrenal glands Has two parts– the adrenal cortex (outside) and adrenal medulla (inside) --Cortex and gonads make the only steroid hormones --Medulla makes neurotransmitters as hormones

Adrenal cortex Outside layer Stimulated by ACTH from ant. pit. Makes steroids --aldosterone—causes kidneys to reabsorb sodium and water --cortisol—causes tissues to increase blood nutrients, allows damaged tissues to heal.

Hormones of the Adrenal Cortex Figure 9.11

Adrenal Medulla Center of the gland Derived from nerve tissue, directly controlled by sympathetic NS Hormones are used in NS as neurotransmitters --norepinephrine-(aka. adrenalin) fight-or-flight --epinephrine (similar to norepinephrine)

For emergency use only Hypothalamus Adrenal medulla Direct sympathetic nerve impulses! Norepinephrine (adrenalin) stimulates fight-or-flight responses

Which hormones and glands are stimulated by: 1)Other hormones and glands? 2)Blood chemistry? 3)Neurons?

Hormonal Stimuli of Endocrine Glands Figure 9.2a Most common Endocrine glands are activated by other hormones Ex: Anterior pituitary hormones

Humoral Stimuli of Endocrine Glands Figure 9.2b Changing blood levels of certain ions stimulate hormone release Humoral indicates various body fluids such as blood and bile Ex: Calcitonin Insulin Parathyroid hormone

Figure 9.2c Neural Stimuli of Endocrine Glands Nerve impulses stimulate hormone release Most are under the control of the sympathetic nervous system  Ex: norepinephrine epinephrine by adrenal medulla

Major Endocrine Organs Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pineal gland Thymus gland Pancreas Gonads (Ovaries and Testes) Hypothalamus