Transcript bio 342 human physiology

Friday, 24 September
Ch 11 Endocrine System
• The Hypothalamus and Pituitary Glands
– Unique anatomy
– Long & short loop negative feedback
• Stress and Cortisol
• Some examples of endocrine disorders
1QQ # 8 for 8:30 class
1. Suppose a biopsy of a patient’s thyroid gland
revealed follicles and follicular epithelial cells that
were less than half the normal size. If you took a
blood sample from that patient, would you predict
the TSH level to be normal, high, or low. Explain
your choice.
2. Your patient’s body temperature is 97.1 F, blood
pressure and heart rate are below normal. You
order a blood test to check for hormone levels.
Which hormone(s) is/are of greatest interest to
you and why? Based on the symptoms, what
predictions do you make about the results of the
blood test? Explain.
1QQ # 8 for 9:30 class
1. Some tumors of endocrine glands result in
unregulated high levels of hormone secretion.
Which would you predict to be more severe: a
tumor in the anterior pituitary gland or a tumor in
the posterior pituitary gland? Explain your
reasoning.
2. Your patient’s body temperature is 97.1 F, blood
pressure and heart rate are below normal. You
order a blood test to check for hormone levels.
Which hormone(s) is/are of greatest interest to
you and why? Based on the symptoms, what
predictions do you make about the results of the
blood test? Explain.
Tropic hormones control the function
S1
Trophic hormones promote survival and growth of targets
P P
P
P
A
P
Hypothalamo-hypophyseal portal system
P
P
S
P
P
P
A
Releasing Hormone
Release-inhibiting Hormone
P
S
Tropic hormones control the function
Trophic hormones promote survival and growth of targets
Short-loop Neg. Feed.
Long-loop negative feedback
Releasing Hormone
Release Inhibiting Hormone
S2
Endocrine disorders
• Hypersecretion
– Primary
– Secondary
• Hyposecretion
– Primary
– Secondary
hypothalamus
CRH
Anterior pituitary
ACTH
Adrenal Cortex
Cortisol
S3
Who
Cares?
S4
• Symptoms of
hypothyroidism
• Levels of TSH
and TH?
• Explain enlarged
thyroid gland
• Cause:
Inadequate
dietary intake of
iodine
• Treatment?
Endemic
Goiter
TRH
TSH
T3 & T4
Goiter
Elevates basal metabolic rate,
potentiates response to EPI
If hypothyroid during pregnancy…
cretinism = congenital hypothyroidism
Who else
Cares?
Aunt Dot
S5
Grave’s Disease
⇩
⇩
TRH from Hypothal.
TSH from Ant. Pit.
T3 and T4 from
Thyroid gland
⇧sensitivity to EPI
(up-regulation of adrenergic receptors)
Blood test:
TSH levels low
TH levels high
The cause: Abnormal
Immunoglobulins in patient
activate TSH receptors on
Thyroid cells
⇧Metabolic rate
⇧Temperature
⇧Heart rate and ⇧Blood Pressure
⇧Lipolysis and fuel mobilization
Weight loss
S6
Grave’s Disease
Treatment:
Radioactive
Iodine
Mechanism:……..
S7
Vasopressin
Cytokines
from
immune cells
CRH from Hypothalamus
ACTH from Ant. Pit
S8
Physical trauma
Prolonged exposure to cold
Prolonged intense exercise
Infection
Sleep deprivation
Pain
Fright
Emotional distress
Basal levels of Cortisol
Required for normal sensitivity to EPI;
symptoms of excess cortisol are…..
Clinical example: treatment of chronic inflammation
(e.g. arthritis) can lead to Cushing’s Syndrome!
⇧Cortisol
secretion from
Adrenal Cortex
Mobilize fuel from muscle & adipose tissue
Suppress non-essential functions
(reproduction & growth)
Suppress inflammatory &
immune responses
Potentiates response to EPI (vascular
smooth muscle)
Cushing’s Syndrome
Excess Cortisol from
1) adrenal cortex tumor (primary) or
2) hypersecretion of ACTH from anterior pituitary (secondary)
S9
Applied Physiology: Menopause
Widmaier text p. 694
•
•
•
•
Onset ~ age 50
Irregular menstrual cycles
Breasts and genital organs gradually atrophy
Decrease in bone mass & strength
(osteoporosis) (bone resorption greater than
bone deposition)
• Hot flashes…sweating, etiology unknown
• Increased incidence of coronary artery disease
Menopause, continued.
• Caused by ovarian failure….loss of estrogen
• Estrogen has protective function for
cardiovascular system and sustains bone
• Diagnosis
– Test estrogen levels
– Test FSH levels….interpretation if high?
• Treatment
– Hormone replacement therapy
– Risk of HRT: increased incidence of breast
cancer & uterine endometrial cancer
– Advantages: alleviates symptoms, restores
cardiovascular protection, sustains bone density
S 10