1. Lecture 8. Regulatory Mechanisms
I. Intercellular Communication and the
Endocrine System
II. Nervous Coordination
2. Intercellular Communication
•
Endocrine signaling: secreted molecules diffuse
into the bloodstream and trigger responses in
target cells anywhere in the body
9. Signaling Molecules: Local Regulators
•
Prostaglandins (PGs)
–
modified fatty acids
–
when secreted by the placenta stimulate uterine
contractions during childbirth
–
promote fever and inflammation and intensify the
sensation of pain
11. Signaling Molecules: Neurohormones
–
secreted by neurosecretory cells
–
diffuse from nerve cell endings into the
bloodstream
–
ADH (vasopressin)
12. Signaling Molecules: Pheromones
–
released into the external environment
–
to mark trails leading to food
–
for defining territories
–
warning of predators
–
attracting potential mates
13. Signaling Molecules: Hormones
–
chemicals that transfer information and
instructions between cells in animals and plants
–
body’s chemical messengers
–
regulate growth and development
–
control the function of various tissues
–
support reproductive functions
–
regulate metabolism
14.
15.
16.
17.
18. Hypothalamus
•
integrates endocrine and nervous function
25. Acromegaly
•
A syndrome that results when the pituitary gland produces
excess growth hormone (GH) after epiphyseal plate closure at
puberty
•
Affects the face and extremities
26. Hypopituitary dwarfism
Decreased bodily growth due to
•
hormonal problems. The end
result is a proportionate little
person, because the height and
growth of all other structures of
the individual are decreased
27. Simple Goiter
•
Enlargement of the thyroid gland
caused by the deficiency of
iodine in the diet
Iodine is a major component of
•
thyroid hormones
Thyrotropic hormone (TSH) from
•
anterior pituitary regulates
synthesis and secretion of thyroid
hormones
During iodine deficiency, TSH
•
overstiumulates the thyroid
gland to extract iodine from the
blood, causing the gland to
enlarge
28. Cretinism
Caused by a malfunction of
•
the thyroid gland at an early
age.
Mentally retarded dwarf
•
Severe stunted physical and
•
mental growth due to
untreated congenital
deficiency of thyroid
hormone (congenital
hypothyroidism) due to
maternal nutritional iodine
deficiency
29. Cushing Syndrome
•
Caused by high levels of cortisol
in the blood
Symptoms include rapid weight
•
gain, particularly of the trunk
and face while sparing the limbs,
growth of fat pads along the
collar bone and on the back of
the neck (buffalo hump), and a
round face (moon face)
30. Melatonin Production
•
“Hormone of darkness” – production by pineal gland
is inhibited by light and promoted by darkness
Blue light (460 – 480 nnm) particularly inhibits
•
melatonin
melatonin signal forms part of the system that
•
regulates the sleep-wake cycle by chemically causing
drowsiness and lowering the body temperature
35. • A lack of PTH causes hypoparathyoidism, a
tetany
–
calcium levels in the blood drop
–
convulsive contractions of the skeletal
muscles
36. •
The pancreas has both endocrine and exocrine
functions
–
Exocrine function: secretion of bicarbonate ions and
digestive enzymes
–
Endocrine function: insulin and glucagon secreted by
islets of Langerhans
37.
38. • Hypoinsulinism: diabetes mellitus
–
hereditary factors and obesity play a role
in its development
–
high blood sugar levels – sugar excreted
in the urine
–
symptoms: excessive urination and
excessive thirst
–
if severe: fat substitutes for glucose as
major fuel source production of acidic
metabolites life threatening lowering
of blood pH
39. • Type I diabetes mellitus (insulin-dependent
diabetes)
–
autoimmune disorder
–
usually appears in childhood
–
treatment: insulin injections
40. • Type II diabetes mellitus (non-insulin-dependent
diabetes)
– usually due to target cells having a decreased
responsiveness to insulin
– usually occurs after age 40 – risk increases
with age
– accounts for over 90% of diabetes cases
– can lead to renal failure, erectile dysfunction,
blindness, slow healing wounds (including
surgical incisions), and arterial disease
– Treated with lifestyle modification and taking
in biguanide metformin
41. •
Epinephrine (adrenaline) and norepinephrine
(noradrenaline).
• catecholamines
• secretion regulated by the nervous system in
response to stress
• raises blood glucose level and blood fatty acid level
• increase metabolic activities
–
increases heart rate and stroke volume and
dilates bronchioles
• shunts blood away from skin, digestive organs, and
kidneys, and increases blood flow to heart, brain,
and skeletal muscle
42. –
Adrenal cortex reacts to stress
• secretion of corticosteroids is regulated by the
nervous system in response to stress
• Glucocorticoids
– raises blood glucose level
– secretion regulated by ACTH (negative feedback)
– abnormally high doses are administered as medication
to suppress the inflammation response
• Mineralocorticoids (example: aldosterone, which
affects salt and water balance).
– promotes reabsorption of Na+ and excretion of K+ in
kidneys
– secretion regulated by K+ in blood
43.
44. –
A third group of corticosteriods are sex
hormones
• androgens secreted by the adrenal cortex
may account for the female sex drive
• the adrenal cortex also secretes small
amounts of estrogens and progesterone
45. •
Testes
–
Androgens (e.g., testosterone)
• supports sperm formation
• promote development and maintenance of
male sex characteristics
• secretion regulated by FSH and LH
46. •
Ovaries
–
Estrogens (e.g., estradiol)
• stimulate uterine lining growth
• promote development and maintenance of
female sex characteristics
• secretion regulated by FSH and LH
–
Progestins (e.g., progesterone)
• promotes uterine lining growth
• secretion regulated by FSH and LH
