Endocrine system

10. What is the role of specificity between hormones and target cells?

A hormone is secreted and that affects the functions of other cells. A target cell is a cell that has a specific receptor for a certain hormone. So a hormone affects only its specific target cell.

3. How are target cells identified by hormones? What is specificity?

A target cell responds to a hormone because it bears receptors for the hormone. In other words, a particular cell is a target cell for a hormone if it contains functional receptors for that hormone, and cells which do not have such a receptor cannot be influenced directly by that hormone.

4. Similarities between different types of hormones (e.g., what do they have in common?).

Hormones act as a chemical signal between cells is a common feature of all hormones.Most hormones have common characteristics, including (1) secretion in small amounts at variable but predictable rates, (2) circulation through the blood, and (3) binding to specific cell receptors in the cell membrane or within the cell.

19. What are the characteristics of hormones?

Hormones affect nearly every process in your body, including: Metabolism (the way you break down food and get energy from nutrients). Growth and development. Emotions and mood. Growth and development, metabolism, blood composition and reproduction.

6.What type of signals do most endocrine glands use? (e.g., frequency modulated, amplitude modulated, etc.)

Hormones are generally considered amplitude-modulated signals. Amplitude modulation is a process by which the wave signal is transmitted by modulating the amplitude of the signal.

9. How does the half-life of a hormone affect its activity? (e.g., short or long duration, rapid or delayed onset?)

Hormones with a shorter half-life regulate activities with a slow onset and long duration.The duration of hormone activity refers to the duration of altered cellular behavior triggered by hormone binding.

23. What types of hormones bind to membrane-bound receptors versus intracellular receptors?

Hydrophobic hormones are able to diffuse through the membrane and interact with an intracellular receptor. Hormones that use intracellular receptors include thyroid, aldosterone, and steroid hormones.

13. What type of mechanism regulates most hormones? (e.g., positive feedback, negative feedback)

Most hormones are regulated by feedback mechanisms. A feedback mechanism is a loop in which a product feeds back to control its own production. Most hormone feedback mechanisms involve negative feedback loops.Negative feedback prevents further hormone secretion once a set point is achieved.

5. Similarities and differences between endocrine and nervous system stimulation.

Similarities: They provide the body with methods to communicate with its internal and external environments in order to coordinate responses. They both employ chemicals to transmit messages and respond to stimulus caused by changes in their environments. Differences:In the nervous system, electrical impulses carry messages to different organs of the body. The endocrine system uses hormones, chemical signals, to carry commands to the destined organs and cells.Nerve or electrical impulses transmit through neurons.Hormones travel through bloodstreams.

8. What is conjugation?

Substances like sulfate or glucuronic acid groups are attached to hormones primarily in the liver, normally making them less active as hormones and increasing the rate at which they are excreted in the urine or bile.

1. What is the function of the endocrine system? How does it secrete chemicals and travel to target cells? (general)

The endocrine system includes glands and specialized endocrine cells that secrete hormones into the bloodstream. The glands secrete chemical substances called hormones, which travel in the bloodstream.

18. Define secretion

production and release of a useful substance by a gland or cell; also, the substance produced. the process of segregating, elaborating, and releasing some material either functionally specialized (as saliva) or isolated for excretion (as urine)

2. Understand the different types of chemical messengers. What cell do they exert an effect on (e.g., location)?

The four classes of chemical messengers are, autocrine, paracrine,neurotransmitter and endocrine. The different types of chemical messengers are hormones, neurotransmitters, neuropeptides, and pheromones. Hormones:a regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action. Neurotransmitters: chemical messengers that your body can't function without. Their job is to carry chemical signals ("messages") from one neuron (nerve cell) to the next target cell. Neuropeptides:are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors. Pheromones: are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavior of the receiving individuals.

22. Understand how hormones are inhibited.

The main release-inhibiting hormones or inhibiting hormones are as follows: The hypothalamus uses somatostatin to tell the pituitary to inhibit somatotropin and to tell the gastrointestinal tract to inhibit various gastrointestinal hormones.

16. What is the role of cAMP when it acts as an intracellular mediator in cells?

The second messenger cyclic AMP (cAMP) is a major intracellular mediator of many hormones and neurotransmitters and regulates a myriad of cell functions, including synaptic plasticity in neurons. It binds to and activates protein kinase.

15. What regulatory protein is associated with membrane-bound receptor molecules?

G proteins, or guanine-nucleotide binding proteins, are a group of different proteins that work as signal transduction switches between membrane-bound receptors and regulatory proteins or pathways at the cell's interior.G proteins are associated with membrane-bound receptor molecules.

12. Describe the different types of hormone stimuli

The three mechanisms of hormonal release are humoral stimuli, hormonal stimuli, and neural stimuli. Humoral stimulation exhibited by hormones that are sensitive to circulating blood levels of certain molecules, such as glucose or calcium.Neural stimuli causes hormone secretion in direct response to action potentials in neurons, as occurs during stress or exercise. Hormones from the hypothalamus that cause the release of other hormones are called releasing hormones. Hormonal stimulation refers to the release of a hormone in response to another hormone.

14. Describe up- and down-regulation.

Up regulation- the number of receptors increases in response to rising hormone levels, making the cell more sensitive to the hormone and allowing for more cellular activity. Down regulation: when the number of receptors decreases in response to rising hormone levels cellular activity is reduced.

17. What happens when a hormone binds to a nuclear receptor?

Upon hormone binding the receptor dissociates from the heat shock protein and translocates to the nucleus.In the nucleus the hormone receptor complex binds to a DNA sequence called a hormone response element which triggers gene transcription and translation.

21. What is an intracellular mediator?

Intracellular mediator are small molecules which help to diffuse within the cell.

7. Differences between lipid and water soluble hormones:

a. Half-life Hormones that are water-soluble such as hormones derived from peptides and amino acids have a shorter half-life than lipid-derived hormones such as steroid hormones.Blood is water-based, lipid-derived hormones must travel to their target cell bound to a transport protein. This more complex structure extends the half-life of steroid hormones much longer than that of hormones derived from amino acids. b. Where do they exert their effect? Lipid-derived (soluble) hormones such as steroid hormones diffuse across the membranes of the endocrine cell. Once outside the cell, they bind to transport proteins that keep them soluble in the bloodstream. Water-soluble hormones bind to a receptor protein on the plasma membrane of the cell. c. How do they travel in the blood Lipid-soluble hormones diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells.Most water-soluble hormones are transported in the blood bound to transport proteins. d. How do they pass the cell membrane? Water-soluble hormones cannot diffuse through the cell membrane. These hormones must bind to a surface cell-membrane receptor.Lipid-soluble hormones easily diffuse through the cell membrane. e. How are they cleared from the body Disposal of waste once hormones have served their functions on their target organ/tissues they are destroyed. They are either destroyed by the liver or the actual tissues of the target organs.They are then removed by the kidney. f. Where are the receptors located For lipid-soluble hormones, the receptor is typically located within the cytoplasm or nucleus of the cell.For water-soluble proteins, the receptor will be at the plasma membrane of the cell.