Ch 45 Notes

2.e.2 – Timing and coordination of physiological
events are regulated by multiple mechanisms
3.b.2 – A variety of intercellular and intracellular
signal transmissions mediate gene expression
(11.1 & 11.4).
3.d.1 – Cell communication processes share
common features that reflect a shared
evolutionary history (11.2 & 11.2).
3.d.2 – Cells communicate with each other
through direct contact with other cells or from a
distance via chemical signaling (11.1 & 11.2).
3.d.3 – Signal transduction pathways link
signal reception with cellular response (11.3).
3.d.4 – Changes in signal transduction
pathways can alter cellular response (11.4).
Endocrine system deals with chemical
control and communication
Uses hormones
◦ Hormone: chemical signal usually transported
through bloodstream, elicits a specific response
from target cell
◦ Produced by endocrine cells (neurosecretory cells)
 Specialized nerve cells
◦ Hormones regulate activity of other cells and
◦ Hormones bind to cell surface receptors
Hypothalamus and
pituitary gland
◦ Produce many hormones
that control production of
other hormones in other
endocrine glands/organs
◦ Nervous system:
coordinates and
◦ Endocrine system: produces
hormones which regulate
bodily processes
A receptor/sensor detects a change (stimulus)
◦ Receptor notifies the control center
◦ Control center sends out an efferent signal which
directs a response by effector
Endocrine cells: acts as both sensor and
control center
◦ Sends out either hormones or signal
Usually controlled via negative feedback loop
Three groups/classes of hormones:
1.Peptide/Protein (water-soluble)
2.Amine (water-soluble)
Types of signals:
1. Hormones: within body (long distance)
2. Local regulators: neighboring cells
3. Phermones: communication between
individual organisms
 Hormones
bind to target cell
◦ Initiate pathways/signals that end in
specific cell responses
Steps of signal response:
1.Reception: Signal binds to specific protein
receptor on target cell
2.Signal transduction: signal’s message is
transmitted via target cell
3.Response: the end result, how the target
cell responds
 Hypothalamus
and pituitary
integrate the endocrine system
◦ Hypothalamus:
 Situated in lower brain
 Integrates endocrine and nervous system
 Receives nerve signals from body
 It’s neurosecretory cells release
 These hormones are stored in or
regulate by the pituitary gland
Pituitary gland:
◦ Located at the base of hypothalamus
◦ Regulate and stores hormones produced by
◦ Two parts:
1.Posterior: stores and secretes two hormones from
2.Anterior: makes at least 6 hormones (tropic
hormones), important to chemical coordination
Antidiuretic hormone (ADH)
◦ Functions in osmoregulation
◦ Increases water retention by kidney (decreases
urine volume)
◦ Produced in posterior pituitary
◦ Induces uterine contractions during birth
◦ Induces milk ejection during nursing
◦ Produced in posterior pituitary
Thyroid-stimulating hormone (TSH)
◦ Regulates production of thyroid hormones
◦ Produce in anterior pituitary gland
Follicle-stimulating hormone (FSH) and
luteinizing hormone (LH):
◦ Stimulate gonad activity
◦ Produced in anterior pituitary
Prolactin (PRL)
Mammals: milk production and secretion
Amphibians: delays metamorphosis
Fish: osmoregulation
Produced in anterior pituitary
◦ Pain perception
◦ Can resemble opiate drugs (giving you a sense of
well-being!) 
◦ Produced in anterior pituitary
Growth hormone (GH):
◦ Variety of target tissues
◦ Signals release of IGFs (Insulin-like growth factors)
◦ Gigantism (human growth disorder caused by
excessive GH)
◦ Produced by anterior pituitary
◦ Produced by liver
◦ Stimulate bone and cartilage growth
T3 and T4:
◦ Produced by thyroid gland
◦ Secretion controlled by negative feedback
◦ Critical to development and maturation
T3 and T4, cont.:
◦ Contributes to homeostasis
 Maintain normal blood pressure, heart rate, muscle
tone, digestion, reproductive function
Blood calcium hormones:
◦ Parathyroid hormone (PTH): stimulate Calcium
resabsorption in kidney, activate vitamin D which
helps uptake of Ca in intestines
◦ Calcitonin: hormone that lowers calcium levels in
Blood glucose hormones:
◦ Glucagon: raises glucose concentrations by
stimulating liver to increase breakdown of
◦ Insulin: lowers glucose concentration by
promoting movement of glucose from blood
into other body cells
◦ Produced by pancreatic cells
◦ Diabetes mellitus: absence of insulin in
bloodstream or loss of response to insulin
 Type-I: autoimmune disorder, treated by regular insulin
 Type-II: 90% of diabetics, insulin deficiency, controlled via
exercise and diet control
Stress hormones:
◦ Epinephrine (adrenaline)
◦ Norepinephrine (noradrenaline)
 Sustain blood pressure
◦ Produced by adrenal glands
◦ Increase availability of energy sources
◦ Increase metabolic rate
Gonadal sex hormones:
◦ Produces by testes and ovaries
◦ Affect growth, development and
reproductive cycles and behaviors
Gonadal sex hormones, cont.:
◦ Three groups:
1. Androgens:
 Produced primarily by testes
 Ex: testosterone (determines gender, stimulate
development of male reproductive system)
2. Estrogens
 Produced by ovaries
 Regulate development and maintenance of
female reproductive system
3. Progestins
 Help prepare and maintain uterus for growth
of embryo
◦ Secreted and produced in pineal gland
(near center of brain)
◦ Regulate functions related to light and
changes in day length
◦ Secretion at night functions with biological
clock for daily or seasonal activities (such
as sleeping, mating, nesting)
Memorization of the names, molecular
structures, and specific effects of hormones
or features of the brain are responsible for
these physiological phenomena is beyond the
scope of the course and the AP Exam.

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