Endocrine and Nervous System

• Hormones – are chemical messengers that are secreted from glands into the blood and affect cells in another part of the body.
• External stimuli: by way of nerves from the sensory organs in the nervous system
• Internal stimuli: by way of nerves and other hormones
• Negative feedback- means that when enough hormone is in the body, the body stops producing the hormone until it is needed again.
• If the feedback stimulates the production of more hormones, it is considered a positive feedback.
• Insulin - stimulates glucose uptake from the blood
• Glucagon - Stimulates glucose release from the cells into blood
• Oxytocin – Stimulates milk secretion and induces uterine contraction
• Calcitonin – stimulates calcium uptake
• Prolactin – Stimulates milk production in women
• Pituitary – Master Gland that regulates all other Endocrine Glands, also releases growth hormone.
• Thyroid – Metabolism, body heat, bone growth.
• Parathyroids – Use of Calcium and Phosphorus.
• Hypothalamus – Links nervous system to endocrine system.
• Adrenal – Response in emergency or stressful situations, metabolism, blood pressure, salt balance.
• Pancreas – Blood sugar.
• Ovaries – Production of eggs; female characteristics.
• Testes – Production of sperm; male characteristics.
• Thymus – Parts of the immune system.
• Hormones only work on certain cells, called target cells.
• The target cells have special receptors that “recognize” the hormones and allow them to influence that cell.
• Notice that organ function is regulated by nerves and hormones.
• Nerve action is quick and can be stopped quickly.
• Hormone action is slower to develop and can last a lot longer.
• Remember, external means coming from outside of your body and internal means coming from inside of your body.