Download 6.6 Hormones & Reproduction

6.6 HORMONES &
REPRODUCTION
Endocrine system
• Produces and releases hormones
• Hormones travel in the blood to target tissues
• Long distance communication between cells
Endocrine
Glands
Blood stream
Hormone
Target
Tissue
Homeostasis
• Ability of the body to maintain stable internal conditions
regardless of external conditions
• Hypothalamus monitors the following:
• Blood pH
• Carbon dioxide concentration
• Blood glucose concentration
• Body temperature
• Water balance
Negative Feedback Loop
• When a change in the body is detected, the body elicits
are response to being the altered level back to where it
was before the change.
Thermoregulation
• Maintaining body temperature at 98.6 degrees
• Regulated by hypothalamus and thyroid
Thermoregulation chart
Cooling Mechanisms
Warming Mechanisms
Sweat glands release sweat for
evaporative cooling
Sweat glands do not release sweat in
order to limit evaporative cooling
Arterioles leading to the skin’s surface
dilate and bring more blood to the
surface for cooling
Arterioles leading to the skin’s surface
constrict and keep blood in the body’s
core tow warm vital organs
The body spreads out (wide arms and
legs) to increase the surface are for
cooling
The body pulls inwards (arms and legs
very close to the body) to decrease
surface area and retain heat
Muscle cells relax and prevent
shivering that would further heat the
body
Muscle cells contract to induce
shivering to produce heat to warm the
body
Blood glucose levels
• Must be maintained within a narrow range
• Regulated by the hypothalamus
• Regulated by two antagonistic hormones by produced by
the pancreas (pancreatic islet cells)
• Alpha cells produce glucagon (increase glucose levels)
• Beta cells produce insulin (decrease glucose levels)
Blood Glucose Regulation
Rise in Blood Glucose Levels
Drop in Blood Glucose Levels
Insulin is released from beta cells
Glucagon is released from alpha cells
Liver cells store glucose as glycogen,
removing glucose from the
bloodstream
Liver cells break down stored
glycogen into glucose and release the
glucose into the bloodstream
Cells take up glucose from the
bloodstream (capillaries)
Cells take up very little glucose from
the bloodstream (capillaries)
Blood sugar levels fall to homeostatic
levels
Blood glucose levels rise to
homeostatic levels
Type I and Type II Diabetes
• Disease where you are unable to control glucose levels
• Type I
• Islet cells lose their ability to produce insulin
• Possible causes
• Autoimmune response, viral infection or genetics
• Type II
• Results when cellular receptors for insulin fail to respond to the
hormone
• Causes
• Obesity or possibly genetics
• Can be reversed by diet and exercise
Type I and Type II Diabetes
Type I Diabetes
Type II Diabetes
Onset
Sudden
Gradual
Prevalence
Less common
More common
Age of onset
Mostly in young children
Usually in adults but due
to childhood obesity
becoming more common
in children
Insulin levels
No insulin production or
very low levels
Normal insulin or altered
(higher or lower) levels
Insulin needs
Must have insulin
injections for survival
Vary with individual
Treatment
Insulin injections/diet
changes
Weight loss with diet and
exercise may use insulin
injections
Applications of Hormone Use
• Can be used to treat or detect disorders of the endocrine
system
Hormone applications
Hormone
Source
Mode of action
Application
Insulin
Beta cells of the
pancreas
Lowers blood
glucose levels
Used to treat type
I diabetes
Thyroxin
Thyroid gland
Increases
metabolic
processes and
thermoregulation
Used as
replacement
therapy for
patients with
reduced thyroid
function
Leptin
Adipose tissue
Acts on the
hypothalamus
inhibiting appetite
Used to help
diagnose causes
of obesity by
testing levels of
leptin in obese
individuals
Melatonin
Pineal gland
Circadian rhythms Used to treat jet
(sleep cycles)
lag