Lecture 24 Hormones and Endocrine System Flashcards
Coordination and control: Endocrine system
● The endocrine system releases
signaling molecules called hormones
into the bloodstream
● A hormone may affect one or more
regions throughout the body
● Hormones are relatively slow acting,
but can have long-lasting effects
Endocrine glands
secrete hormones directly into surrounding fluid
Exocrine glands
have ducts and which secrete substances onto body surfaces or into cavities
Exocrine system anatomy
eyes (tears), Mouth(saliva), skin(sweat, sebum), stomach (enzymes), Breasts (milk), Liver (bile), Pancreas( juices), intestines (mucus)
intercellular communication
- cells that send the signal
- only cells expressing the receptor can perceive the signal
Intercellular communication (secreted signals) how is it classified
Communication between animal cells
through secreted signals can be
classified by two criteria:
1. The route taken by the signal in
reaching its target
2. The type of secreting cell
types of cell signaling
● endocrine ● paracrine ● autocrine ● synaptic ● neuroendocrine
Paracrine versus Autocrine signaling
slide 13
In paracrine signaling, the target cells lie near the
secreting cells.
In autocrine signaling, the target cell is also the
secreting cell.
Local regulators
molecules that act over short distances, reaching target cells solely by diffusion
(paracrine and autocrine)
paracrine signaling
the target cells lie near the secreting cells
autocrine signaling
the target cells is also the secreting cell
Endocrine signaling
● Hormones secreted into extracellular fluids by endocrine cells reach their targets via the bloodstream.
● Endocrine signaling maintains homeostasis, mediates responses to stimuli, and regulates growth and development.
Neuroendocrine signalling
In neuroendocrine signaling, specialized neurosecretory cells secrete neurohormones that diffuse from nerve endings into the bloodstream (slide 16 and 17)
Intercellular communication by secreted molecules
slide 18
Pancreas: insulin
slide 19
Diabetes Mellitus
slide 20
signaling by pheromones
used by some animals to commumicate, pheromones are chemicals that are released into the environment
Pheromones serve many functions, including marking trails leading to food, defining territories, warning of predators, and attracting potential mates
Endocrine signaling - hormones
● Hormones secreted into extracellular fluids by endocrine cells reach their targets via the bloodstream.
● Endocrine signaling maintains homeostasis, mediates responses to stimuli, and regulates growth and development.
Endocrine signaling: hormones what are they?
● The endocrine system transmits chemical signals called hormones to receptive cells throughout the body via blood.
● A hormone may affect one or more regions throughouthe body.
● Hormones are relatively slow acting, but can have long-lasting effects.
3 classes of hormones
polypeptides, steroids, and amines
What do poplypeptides and (most) amines have in common?
They are water - soluble
what do Steroid hormones and otehr largely non-polar hormones have in common?
they are lipid - soluble
classes of hormones
slide 26
polypeptide=water soluable
steroids=lipid soluable
amines=both
Receptor localization in the receiving cell
slide 30
water soluable receptor= on cellular membrane
lipid soluable receptor= inside nucleus
How steroid hormone receptors work
slide 31 and 32
Water- vs. lipid-soluble hormones
slide 33
Transmembrane receptors are on the cell surface (steps of activation)
1.Signal reception
2. Signal transduction
3. Cellular response
(slide 34)
Crosstalk and specificity
Crosstalk between signaling pathways allows for nuanced/integrated responses to complex combinations of stimuli
(slide 35)
Epinephrine:Second messengers
slide 36
Epinephrine: Second messengers
slide 37
Principle
a fundamental truth or proposition that serves as the foundation for a system of belief or behavior or for a chain of reasoning.
Endocrine signaling review
slide 39
Human endocrine glands and their hormones.
slide 41
What are Endocrine glands
Endocrine cells are often grouped in ductless organs call endocrine glands, such as the thyroid and parathyroid glands and testes or ovaries.
NOTE: Some endocrine glands produce several hormones
Simple Endocrine Pathways
● Endocrine cells respond directly to an internal or environmental stimulus
● Hormones are secreted from an endocrine cell
● Hormones travel through the bloodstream
● Hormones interact with specific receptors within a target cell
● Consequence - physiological response
Simple Endocrine Pathways (secretion of secretin)
slide 44
Simple Neuroendocrine Pathways
● A sensory neuron respond directly to an internal or environmental stimulus
● Stimulation of a neurosecretory cell
● Neurohormones are secreted from an neurosecretory cell
● Neurohormones travel through the bloodstream
● Interact with specific receptors within a target cell
● Consequence - physiological response
Simple Neuroendocrine Pathways (secretion of oxytocin)
slide 46
Hypothalamus (vertebrates)
receives information from the nervous system and initiates responses through the endocrine system
Pituitary glands (vertebrates)
it is attached to the hypothalamus and is composed of the posterior pituitary and anterior pituitary
what are the two pituitary glands?
posterior pituitary (PP)
anterior pituitary (AP)
Posterior pituitary (PP)
stores and secretes hormones that are made in the hypothalamus.
Anterior pituitary (AP)
makes and releases hormones under regulation of the hypothalamus
Posterior pituitary
slide 49 and 50
Homeostasis: Osmolarity
● Osmoreceptor cells in the hypothalamus monitor blood osmolarity and regulate release of ADH from the posterior pituitary.
● When osmolarity rises above its set point, ADH release into the bloodstream increases.
● When osmolarity drops below a set point, it causes a reduction in ADH secretion.
Homeostasis: Osmolarity cycle
slide 52
Anterior pituitary
slide 53 and 54
Anterior pituitary hormones
slide 55
Hormone cascades
● Sets of hormones from the hypothalamus, anterior pituitary, and a target endocrine gland are often organized into a hormone cascade.
● The anterior pituitary hormones in these
pathways are called tropic hormones.
indirectly affect target cells by first stimulating other endocrine glands.
The reproductive cycles of the human male
slide 57
Sex Hormones
Y- chromosome
● Testosterone
● AMH (antimullerian hormone)
Thyroid hormone secretion
slide 60
Adrenal Hormones: Response to Stress
● The adrenal glands are located atop the kidneys.
● Each adrenal gland consists of two glands: the adrenal medulla (inner portion) and adrenal cortex (outer portion).
Adrenal medulla
secretes epinephrine and norepinephrine
Adrenenal cortex
secretes mineralocorticoids and glucocorticoids
Anterior pituitary hormones
slide 64
The adrenal cortex
● The adrenal cortex becomes active under stressful conditions including low blood sugar, decreased blood volume and
pressure, and shock.
● A series of hormonal signals lead to production and secretion of a family of steroids called corticosteroids.
● Humans produce two types of corticosteroids: glucocorticoidsand mineralocorticoids.
corticosteroids
a series of hormonal signals lead to production and secretion of a family of steroids
The Role of the Adrenal Medulla
● The adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline).
● They coordinate a set of physiological responses that comprise the “fight-or-flight” response.
Stress and the adrenal cortex
slide 67
Noradrenaline
Rapid response to stress
fight or flight
Epinephrine and norepinephrine: multiple effects
● Trigger the release of glucose and fatty acids into the blood.
● Increase oxygen delivery to body cells.
● Direct blood toward heart, brain, and skeletal muscles and away from skin, digestive system, and kidneys.
Epinephrine: Second messengers
slide 71
Epinephrine: one hormone, different effects
slide 72
