Master this deck with 19 terms through effective study methods.
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The nervous system uses electrical impulses to transmit signals rapidly across synapses, allowing for quick responses, while the endocrine system uses hormones released into the bloodstream for slower, longer-lasting effects. The nervous system is localized, affecting specific target cells, whereas the endocrine system has a more widespread influence.
Endocrine glands secrete hormones directly into the bloodstream and do not have ducts, while exocrine glands release their secretions through ducts to the outside of the body or into body cavities, such as sweat glands and salivary glands.
Hormones are chemical messengers released into the bloodstream that affect distant target cells. Paracrine messengers act on nearby cells within the same tissue, while autocrine messengers act on the same cell that secretes them.
Hormones bind to specific receptors on target cells, which triggers a cascade of intracellular events. Only cells with the appropriate receptors can respond to a particular hormone, ensuring specificity in hormonal action.
Hormones can be classified into three main chemical classes: peptides (water-soluble, composed of amino acids), steroids (lipid-soluble, derived from cholesterol), and monoamines (derived from single amino acids). Their solubility affects their transport in the bloodstream and their mechanism of action on target cells.
Lipid-soluble hormones can pass through the cell membrane and bind to intracellular receptors, leading to changes in gene expression. Water-soluble hormones bind to receptors on the cell surface, activating second messenger systems to produce intracellular effects.
The hypothalamus regulates the endocrine system by producing releasing and inhibiting hormones that control the anterior pituitary gland. It also produces hormones stored in the posterior pituitary gland, influencing various physiological processes.
The anterior pituitary gland is located at the base of the brain and is responsible for producing hormones like growth hormone and prolactin. The posterior pituitary gland, also at the base of the brain, stores and releases hormones like oxytocin and vasopressin produced by the hypothalamus.
The thyroid gland primarily releases thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, growth, and development. It also produces calcitonin, which helps regulate calcium levels in the blood.
The adrenal glands produce hormones such as cortisol, which regulates metabolism and stress response, and adrenaline (epinephrine), which prepares the body for 'fight or flight' responses. Aldosterone regulates sodium and water balance.
Negative feedback is a regulatory mechanism in which an increase in a hormone's level leads to a decrease in its production. This helps maintain homeostasis by preventing excessive hormone levels and ensuring balanced physiological responses.
Gigantism is caused by excess growth hormone during childhood, leading to excessive growth and height. Acromegaly occurs in adults due to excess growth hormone, resulting in enlarged bones and tissues, particularly in the hands, feet, and face.
Dwarfism is characterized by short stature resulting from genetic or hormonal factors, such as growth hormone deficiency. It can be caused by various genetic mutations or conditions affecting growth plate development.
Goiter is an enlargement of the thyroid gland, often caused by iodine deficiency, leading to insufficient production of thyroid hormones. It can also result from autoimmune diseases like Hashimoto's thyroiditis or overproduction of thyroid hormones.
Hypothyroidism (hypo-secretion) can lead to fatigue, weight gain, and sensitivity to cold, while hyperthyroidism (hyper-secretion) can cause weight loss, increased heart rate, and anxiety. Both conditions disrupt normal metabolic processes.
Type 1 diabetes is an autoimmune condition where the immune system attacks insulin-producing beta cells in the pancreas, leading to insulin deficiency. Symptoms include excessive thirst, frequent urination, and weight loss.
Type 2 diabetes is primarily caused by insulin resistance and is often associated with obesity and sedentary lifestyle. Symptoms include increased thirst, frequent urination, fatigue, and blurred vision.
Feedback pathways involve a series of hormonal signals that regulate the production and release of hormones. For example, an increase in hormone levels may signal the hypothalamus or pituitary gland to reduce hormone production, maintaining balance.
Hormones can be classified as steroid hormones (lipid-soluble), peptide hormones (water-soluble), or monoamines (derived from amino acids). This classification affects their synthesis, transport, and mechanism of action in the body.