Chapter 32/37 Flashcards
Homeostasis
Steady state, maintaining the internal environment. Humans maintain around 37 degrees Celsius.
Endothermic
Warmed by heat generated by metabolism i.e. mammals and birds.
Ectothermic
Gaining heat from external sources. i.e. lizards
Structure of a Homeostatic System
- Animals maintain a set point.
- Fluctuations above or below the set point actor as the stimulus, detected by a sensor (the receptor)
- A control center generates output that triggers a response.
Endocrine System
Signaling molecules released into the bloodstream by endocrine cells are carried to all locations in the body.
Nervous System
Neurons transmit signals along dedicated routes connecting specific locations in the body.
(Can only affect other neurons, muscle cells, endocrine cells, and exocrine cells)
Hormones
Signaling molecules broadcast throughout the whole body used by the endocrine system.
Pineal
Hormone: melatonin.
Action: circadian rhythm.
Anterior Pituitary
Hormone: GH
Action: cell growth.
Posterior Pituitary
Hormone: ADH
Action: water balance.
Thyroid
Hormone: T3/T4, Calcitonin
Action: metabolism.
Parathyroid
Hormone: PTH
Action: Raises blood Ca.
Pancreas
Hormone: insulin
Action: Lowers blood sugar.
Adrenal Cortex
Hormone: glucocorticoids.
Action: anti-inflammatory.
Adrenal Medulla
Hormone: Epinephrine. (Adrenaline)
Action: Fight or flight.
Ovary
Hormone: estrogen.
Action: female sex characteristics.
Testes
Hormone: testosterone.
Action: male sex characteristics.
Local Regulators
messenger molecules that travel short distances, example? – growth factors - compounds that stimulate nearby target cells to grow and divide
Neurotransmitters
Any of a group of substances that are released on excitation from the axon terminal of a presynaptic neuron of the central or peripheral nervous system and travel across the synaptic cleft to either excite or inhibit the target cell.
Pheromones
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Water-Soluble Hormones
Unable to pass through the plasma membranes of cells, they bind to cell-surface receptors, triggering events at the plasma membrane that result in cellular response. This is SIGNAL TRANSDUCTION.
Lipid-soluble Hormones
The receptors for the hormones are in the cytosol rather than on the cell surface. When it binds, a hormone-receptor complex forms, which then moves into the nucleus.
Signal Transduction
The cascade of processes by which an extracellular signal (typically a hormone or neurotransmitter) interacts with a receptor at the cell surface, causing a change in the level of a second messenger (for example calcium or cyclic AMP) and ultimately effects a change in the cells functioning
Simple Endocrine Pathway
- A stimulus in an endocrine cell causes the excretion of hormones.
- This travels to targets via the bloodstream.
- From here it binds to specific receptors.
Glucose Homeostasis:
Insulin is a hormone released by the pancreas to maintain homeostasis.
Insulin facilitates glucose transport into cells from the bloodstream.
Insulin also lowers blood glucose levels.
It also inhibits glucose production from amino acids, fatty acids, and glycogen.
Glucagon is another hormone produced by the pancreas; it raises blood glucose levels by stimulating glycogen breakdown into glucose.
Hypothalamus
Integrates the endocrine and nervous systems.
Receives information from nerves throughout the body, including the brain.
Signals from the hypothalamus travel to a gland located at its base, the pituitary gland, which has discrete anterior and posterior parts.
Pituitary Gland
Anterior Pituitary: synthesizes and releases hormones that regulate other endocrine glands.
Posterior Pituitary: an extension of the hypothalamus. It stores and releases two hormones, oxytocin and ADH, which are synthesized by the hypothalamus’ neurosecretory cells.
Hormone
Signaling molecules broadcast throughout the body via the endocrine system. It gets a response from cells that have a receptor for the signal.
Schwann Cells
Myelinating and non-myelinating; Myelinating Schwann Cells wrap around the axons of motor and sensory neurons to form the myelin sheath.
