1. Chapter 20 Endocrine System

2. Fig. 20.1
Endocrine glands transmit signals through blood stream to cells far away
Different from nervous system; Neuron can affect only cells it contacts
Endocrine gland
Neuron
Hormone
Nerve
signal
Blood
Target cells
Target cells
Neurotransmitter
(a) Nervous system
(b) Endocrine system

3. Fig. 20.2 Major endocrine glands Organs containing endocrine cells
Hypothalamus
Pituitary gland
Pineal gland
Thymus
Heart
Thyroid gland
Kidney
Gastrointestinal (GI) tract
Pancreatic islets
Parathyroid glands
Adrenal glands

4. Fig. 20.4
Hypothalamus
The hypothalamus produces regulatory hormones that either stimulate or inhibit anterior pituitary hormone secretion.
The hypothalamus produces
two hormones (antidiuretic
hormone and oxytocin) that are
stored in and released from
the posterior pituitary.
Anterior
pituitary
Posterior
pituitary

5. Adrenal glucocorticoids
Adrenal cortex
Adrenal cortex secretes three types of steroid hormones
Aldosterone (aka mineralocorticoid)
Glucocorticoids, including cortisol
Increase plasma glucose concentrations
Sex hormones, including estrogens, progesterone, and androgens
DHEA (dietary supplement) converted to testosterone
Kidney

6. Growth hormone Released by anterior pituitary throughout life Anabolic
Hypothalamus
Released by anterior pituitary throughout life
Anabolic
Required for growth in childhood
Combined with thyroid, insulin, sex hormones in some cases
In adults, GH stimulates release of insulin-like growth factors (IGF)
Stimulate bone and soft tissue growth
Anterior
pituitary
Posterior
pituitary

7. Growth hormone pathologies
In childhood, lack of GH leads to dwarfism with proportional body
(one of many possible causes of dwarfism)

8. Growth hormone pathologies
Excessive GH leads to acromegaly
Long jaw, coarse facial features, excessive height

9. Thyroid In adults: In children Increase oxygen consumption in tissues
Larynx
Thyroid gland
Trachea
Thyroid
In adults:
Increase oxygen consumption in tissues
Modulate metabolism of proteins, carbohydrates, and fat
In children
Necessary for expression of growth hormone
Necessary for development of nervous system
Figure 23.4 (2 of 6) 9

10. Fig
Hypothalamus secretes thyrotropin-releasing hormone (TRH), which acts on the anterior pituitary.
Hypothalamus
stimulatory
inhibitory
Negative feedback
inhibition
TRH
Anterior
pituitary
TSH
Anterior pituitary releases thyroid-stimulating hormone (TSH).
Thyroid gland releases thyroid hormone (TH). TH
Target cells increase metabolic activities.
Target organs in body
Secretion of TRH by the hypothalamus is inhibited. TH prevents the formation
of TSH in anterior pituitary 1 2 3 4 5

11. Hyperthyroidism
Elevated TSH causes enlargement of thyroid gland = goiter
Increases oxygen consumption and metabolic heat production
Causes warm, sweaty skin; intolerance to heat
Protein catabolism causes weak muscles
Weight loss
Hyperexcitable reflexes
Insomnia, irritability, psychosis
Rapid heartbeat

12. Hyperthyroidism Graves’ disease
Body produces antibodies that mimic TSH
Thyroid overstimulated
May cause exophthalmos (bulging eyes)
Caused by enlargement of tissues around eyes
Marty Feldman

13. Parathyroid gland Regulates calcium levels in the blood
vital for muscle contractions

14. Pancreas Located behind stomach Fig. 20.15 Body of pancreas Spleen
Pancreatic
ducts
Tail of
pancreas
Major
duodenal
papilla
Duodenum
of small
intestine
Head of
pancreas

15. Pancreas Acinar cells produce digestive juices (not endocrine)
Fig
Fig
Pancreas
Blood
capillary
Acinar cells produce digestive juices (not endocrine)
Pancreatic islets are clusters of endocrine cells
Delta cell
F cell
Pancreatic islet cells
Alpha cell
Beta cell
Pancreatic
acinus
Alpha cell
Beta cell
Delta cell
F cell
Pancreatic islet

16. Pancreas Alpha cells secrete glucagon when blood glucose is low
Fig
Fig
Pancreas
Blood
capillary
Alpha cells secrete glucagon when blood glucose is low
Beta cells secrete insulin when blood glucose is high
Delta cells and F cells affect digestion and release of insulin and glucagon
Delta cell
F cell
Pancreatic islet cells
Alpha cell
Beta cell
Pancreatic
acinus
Alpha cell
Beta cell
Delta cell
F cell
Pancreatic islet