Hormones and Endocrine System

target receptors

what do hormones and other signalling molecules bind to triggering specific response pathways

feedback regulation and coordination

what in the nervous system is common in the endocrine system

circulatory system

where are hormones (chemical signals) secreted into to communicate regulatory messages

endocrine and nervous system

the two systems that coordinate communication throughout the body

endocrine system

system that secretes hormones that coordinate slower but longer acting responses

nervous system

system that conveys high-speed electrical signals along specialized cells called neurons through dedicated pathways (signals regulate other cells)

type of secreting cell, route taken by a signal in reaching its target

The ways signals are transmitted between animal cells are classified by which two criteria

maintains homeostasis, regulates growth and development, mediates responses to stimuli

responsibilities of endocrine system

bloodstream

how do the hormones that are secreted into the extracellular fluid by endocrine cells reach to targets

local regulators

molecules that act over short distances and reach target cells only by diffusion

paracrine signalling

the target cells lie near the secreting cells & of different type

autocrine signalling

the target cell is also the secreting cell and/or the same type of cell

synaptic signalling

neurons form specialized junctions with target cells called synapses (paracrine is a muscle, autocrine if neuron)

neurotransmitters

at synapses, neurons secrete __ that diffuse short distances and bind to target cell receptors

neuroendocrine signalling

type of signalling where specialized neurosecretory cells secrete neurohormones that travel to target cells via the bloodstream

pheromones

used by members of animal species to communicate; are chemicals that are released into the environment

polypeptides, amines from amino acids, steroid hormones

three major classes of hormones in vertebrates

lipid soluble hormones

pass easily through cell membranes (steroid hormones)

water-soluble hormones

dont pass easily through the cell membrane (polypeptides and amines)

gas

Many cells can produce this that have local signalling effects due to their small size and lack of charge which allows for them to diffuse freely

proteins

many of the most familiar hormones are __ encoded by genes (insulin, growth factors)

amine hormones

hormones that are signalling factors produced from amino acids (neuronal signalling factors)

water-soluble hormones

hormones that are secreted by exocytosis, travel freely in the bloodstream, and bind to cell surface receptors

lipid soluble hormones

diffuse across cell membranes, travel in bloodstream bound to transport proteins, diffuse through membrane of target cell and bind to receptors in the cytoplasm or nucleus

signal transduction pathway

binding of a hormone to its receptor leads to what

epinephrine

multiple effects in mediating the bodys response to short term stress; can trigger a pathway which breaks down glycogen which released glucose into bloodstream

change in gene expression

what is the usual response to lipid-soluble hormones

type of receptor and signal transduction pathway

same hormones can have different effects on cells depending on what

thyroid hormones

hormones that regulate metabolism in vertebrates; also control the metamorphosis of the larva into adult in frogs

endocrine glands

where the endocrine cells are often grouped into ductless organs(thyroid, parathyroid, testes, ovaries); these secrete hormones directly into surrounding fluid

exocrine glands

(salivary glands) ducts which carry secreted substances onto body surfaces or into body cavities

regulatory pathways

hormones are assembled into __ __

positive feedback loop

reinforces a stimulus to produce an even greater response (oxytocin)

negative feedback loop

loop inhibits a response by reducing the initial stimulus, thus preventing excessive pathway activity

simple neuroendocrine pathway

In a simple neuroendocrine pathway, the stimulus is received by a sensory neuron, which stimulates a neurosecretory cell The neurosecretory cell secretes a neurohormone, which enters the bloodstream and travels to target cells

oxytocin

released from the posterior pituitary due to nerve impulses from the hypothalamus

ecdysteroid

found in invertebrates where when in presence of juvenile hormone, moulting is promoted, but in absence of JH, the development of adult characteristics

posterior hypothalamus

which part of the hypothalamus stores and secretes hormones

hypothalamus

what plays a central role in integrating the endocrine and nervous systems

pituitary gland

is attached to the hypothalamus and has a posterior and anterior side

nervous, endocrine

The hypothalamus receives information from the __ system and initiates responses through __ signalling

posterior pituitary

the extension of the hypothalamus which stores and secretes hormones the hypo

anterior pituitary

extension of the hypothalamus which makes and releases hormones under the regulation of the hypothalamus

oxytocin, antidiuretic hormone

two hormones released from the posterior pituitary that act on nonendocrine tissue

oxytocin

regulates milk secretion by mammary glands

releasing and inhibiting

Hormone production in the anterior pituitary is controlled by __ and __ hormones secreted from the hypothalamus

tropic hormones

many anterior pituitary hormones act as __ __; regulate function of other endocrine cells or glands

thyroid hormone

a hormone that in humans and other mammals regulates many functions

thyroropin-releasing hormone (TRH)

what is released by the hypothalamus when thyroid levels are low

thyroid stimulating hormone (TSH)

secreting by anterior pituitary when TRH is released

Hypothyroidism

too little thyroid function, can lead to symptoms such as Weight gain, lethargy, cold intolerance

Hyperthyroidism

excessive production of thyroid hormone, can lead to High temperature, sweating, weight loss, irritability, and high blood pressure

Malnutrition

(e.g., iodine deficiency) can alter thyroid function (e.g., disruption of negative feedback loop)

growth hormone (GH)

the hormone that is secreted by the pituitary gland that has tropic and nontropic effects; promotes growth directly

parathyroid hormone (PTH), calcitonin

the two antagonistic hormones that regulate the homeostasis of calcium

parathyroid glands

what released parathyroid hormones

thyroid gland

what released calcitonin

increases level of blood Ca2+

what does PTH do

decreases level of blood Ca2+

what does calcitonin do

adrenal medulla (inner portion), adrenal cortex (outer portion)

two glands of the adrenal gland

epinephrine and norepinephrine

what two things does the adrenal medulla secrete

corticosteroids

the adrenal cortex releases what after reacting to endocrine signals

corticosteroids, glucocorticoids

what two corticosteroids are produced from the hormone cascade pathway