What is the Endocrine System? A system of glands, each of which secretes a type of hormone directly into the bloodstream to regulate the body. Hormones released directly into the blood are referred to as endocrine hormones.

Homeostasis – NS & ES These two systems actually work together to maintain homeostasis! Like the Nervous System, the Endocrine System communicates with parts of the body. Instead of transmitting messages along neurons, hormones are released to bring about change/ body responses.

NS & ES Homeostasis…  Both are important chemical control systems that enable the body to communicate to various body parts. The nervous system enables the body to adjust quickly to changes in the environment. The endocrine system is designed to maintain control over a longer duration.

Glands A gland is an organ. There are many glands found in the human body. Each synthesize (make) and release substances. Glands can synthesis chemicals called hormones or substances such as breast milk and sweat. Endocrine Glands –secrete hormones into the bloodstream. Some glands produce a number of different hormones….such as the Pituitary Gland!

What are Hormones? Hormones are chemical substances that carry a message and activate change in another part of the body. Target Hormones Hormones that can only be used by specific body organs. The organs they go to are known as ‘target organs’. Follicle Stimulating Hormone (FSH), Parathyroid Hormone Nontarget Hormones Hormones that affect many cells throughout the body Examples: Growth Hormone, Insulin, Epinephrine

hypothalamus pituitary gland

Endocrine Glands - Pituitary Often referred to as the “master gland” because it controls when other glands release their hormones. Small sac-like structure composed of two lobes: a posterior lobe and anterior lobe. Connected to the hypothalamus by a stalk of nerve fibers. Produces and stores hormones In particular, stores hormones made by the hypothalamus

Endocrine Gland - Hypothalamus The area of the brain associated with homeostasis Found above the pituitary gland, and connected by nerves Together with the pituitary, functions as a control centre, coordinating the actions of the endocrine and nervous systems

Hypothalamus Hormones Secrete two hormones: oxytocin and antidiuretic hormone Hormones produced in the hypothalamus move to the pituitary gland via nerves and bloodstream where they are used/stored.

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Endocrine Gland - Thyroid Is located in the neck just below the larynx and in front of the trachea. One of the largest endocrine glands. The thyroid gland makes various thyroid hormones, each with their own roles. Thyroxine – regulates the rate of metabolism in the body The pituitary gland tells the thyroid when to release its hormones.

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Endocrine Gland- Adrenal There is one adrenal gland sitting on top of each kidney. Mainly responsible for releasing hormones in response to stress. Adrenaline Epinephrine

Initiation of Fight or Flight Response Initiation of Physiologi c Cascade  Heart Rate  Alertness  O 2 to muscles, not digestion Sensory Perception (Ears, Eyes, Nose, Touch, Taste) Internal Signals (Thoughts, Emotions, Physical) DANGER! Brain Registers DANGER! Prepared to Fight or Flee for Safety & Protectio n

Anxiety Initiation of Physiologi c Cascade  Heart Rate  Alertness  O 2 to muscles, not digestion Sensory Perception (Ears, Eyes, Nose, Touch, Taste) Internal Signals (Thoughts, Emotions, Physical) Brain Registers DANGER! No Danger Anxiety

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Endocrine Glands: Pancreas The hormones secreted by the pancreas mainly control the sugar levels in the body. Glucagon – help to raise blood sugar levels Insulin – help to lower blood sugar levels

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Endocrine Glands: Gonads Ovaries Produce egg cells and release female sex hormones (sex steroids). Estrogen and Progesterone, also produces small amounts of testosterone Testes Produce sperm cells and release male sex hormones (sex steroids) Testosterone

Negative Feedback & Hormones Is a type of control system that regulates hormone production Works similar to a thermostat on your furnace When the desired change is detected, the original action is inhibited

Examples: Steroid & Protein Hormones Both are target Hormones Steroid Hormones Made from cholesterol Male and female sex hormones are steroid hormones There are other steroid hormones too! Protein Hormones Contain chains of amino acids Include Insulin and Growth Hormone

Action of Steroid Hormones Hormone diffuses through cell membrane of target cell Hormone combines with receptor molecule They move into the nucleus and attach to DNA DNA activates a gene to produce a specific protein

Action of Steroid Hormones

Action of Protein Hormones Hormone attaches to receptor on cell membrane of target cell This causes cyclic AMP to be formed which acts as a messenger within the cell Cyclic AMP activates enzymes in the cytoplasm which creates the desired hormonal effect

Action of Protein Hormones