This chapter includes contents: The body’s long-distance regulators; the endocrine system and the nervous system act individually and together in regulating an animal’s physiology; hormones and other chemical signals bind to target cell receptors, initiating pathways that culminate in specific cell responses; the hypothalamus and pituitary integrate many functions of the vertebrate endocrine system;. | Chapter 45 Hormones and the Endocrine System Overview: The Body’s Long-Distance Regulators An animal hormone Is a chemical signal that is secreted into the circulatory system and communicates regulatory messages within the body Hormones may reach all parts of the body But only certain types of cells, target cells, are equipped to respond Insect metamorphosis Is regulated by hormones Figure Concept : The endocrine system and the nervous system act individually and together in regulating an animal’s physiology Animals have two systems of internal communication and regulation The nervous system and the endocrine system The nervous system Conveys high-speed electrical signals along specialized cells called neurons The endocrine system, made up of endocrine glands Secretes hormones that coordinate slower but longer-acting responses to stimuli Overlap Between Endocrine and Nervous Regulation The endocrine and nervous systems Often function together in maintaining homeostasis, development, and reproduction Specialized nerve cells known as neurosecretory cells Release neurohormones into the blood Both endocrine hormones and neurohormones Function as long-distance regulators of many physiological processes Control Pathways and Feedback Loops There are three types of hormonal control pathways Pathway Example Stimulus Low blood glucose Receptor protein Pancreas secretes glucagon ( ) Endocrine cell Blood vessel Liver Target effectors Response Pathway Example Stimulus Suckling Sensory neuron Hypothalamus/ posterior pituitary Neurosecretory cell Blood vessel Posterior pituitary secretes oxytocin ( ) Target effectors Smooth muscle in breast Response Milk release Pathway Example Stimulus Hypothalamic neurohormone released in response to neural and hormonal signals Sensory neuron Hypothalamus secretes prolactin- releasing hormone ( ) Neurosecretory cell Blood vessel Anterior pituitary secretes prolactin ( ) Endocrine cell Blood vessel Target effectors Response Mammary . | Chapter 45 Hormones and the Endocrine System Overview: The Body’s Long-Distance Regulators An animal hormone Is a chemical signal that is secreted into the circulatory system and communicates regulatory messages within the body Hormones may reach all parts of the body But only certain types of cells, target cells, are equipped to respond Insect metamorphosis Is regulated by hormones Figure Concept : The endocrine system and the nervous system act individually and together in regulating an animal’s physiology Animals have two systems of internal communication and regulation The nervous system and the endocrine system The nervous system Conveys high-speed electrical signals along specialized cells called neurons The endocrine system, made up of endocrine glands Secretes hormones that coordinate slower but longer-acting responses to stimuli Overlap Between Endocrine and Nervous Regulation The endocrine and nervous systems Often function together in maintaining homeostasis, .
