ENDOCRINE SYSTEM

ENDOCRINE SYSTEM

Systemic communication

Involves the release of chemical signals for

transport through the blood to influence cellular

activity

Endocrine glands

Hormones

2

Endocrine Glands

Endocrine glands

Glandular tissues that secrete

products (hormones) which

travel through the blood stream

to give instructions to other parts

of the body

3

Signal Recognition

Peptide hormones

Bind to receptors at plasma

membrane surface

Do not enter cell

Signal transduction

Message relayed and

amplified through other

intracellular molecules

“2nd messenger system”

Regulates enzyme systems

& gene transcription

4

Signal Recognition

Steroid hormones

Pass through plasma

membrane

Bind intracellular receptors

in cytoplasm or nucleus

Regulates gene

transcription

5

Hormone Control

Negative feedback

Increased hormone levels inhibit further production

E.g., thyroid hormone

Endocrine gland hormone effector

Positive feedback

Increased hormone levels stimulate further production

E.g., oxytocin

X

6

Quick Quiz: A peptide hormone binds

to _________ receptors, then causes a

signal transduction cascade inside the

cell.

A) Intracellular

B) Extracellular

C) Cell surface (plasma membrane)

7

Quick Quiz: Negative feedback

_________ the original stimulus.

A) Reinforces

B) Opposes

8

Major Vertebrate

Endocrine Glands

Hypothalamus

Pituitary gland

Thyroid gland

Parathyroid glands

Thymus

Adrenal glands

Pancreas

Ovaries / testes

Other (heart, kidneys, liver, stomach,

small intestine, adipose tissue) 9

Hypothalamus & Pituitary Gland

Major hormones of the

posterior pituitary

Produced in hypothalamus,

stored in posterior pituitary

Antidiuretic hormone (ADH)

Targets kidneys

Reabsorb water

Oxytocin (OCT)

Mammary glands milk

letdown

Uterus contractions

10

Quick Quiz: Which of these hormones

is NOT released by the posterior

pituitary?

A) Oxytocin

B) Antidiuretic hormone

C) Growth hormone

11

Hypothalamus & Pituitary Gland

Hypothalamus controls the

anterior pituitary

Releasing hormones

Inhibiting hormones

12

Major Hormones of the Anterior Pituitary

Adrenocorticotropic

hormone (ACTH)

Release of hormones

from adrenal cortex

Thyroid stimulating

hormone (TSH)

Release of thyroid

hormones

13

Major Hormones of the Anterior Pituitary

Follicle stimulating

hormone (FSH) &

luteinizing hormone

(LH)

Stimulate hormonal

secretions of gonads

Prolactin (PRL)

Stimulates milk

production

14

Major Hormones of the Anterior Pituitary

Growth hormone

(GH)

Promotes growth

in all body tissues

15

Quick Quiz: Which anterior pituitary

hormone causes the adrenal cortex to

release hormones?

A) TSH

B) FSH

C) GH

D) ACTH

16

Growth Hormone Imbalances

Childhood

Overproduction

Gigantism

Underproduction

Dwarfism

Adult

Overproduction

Acromegaly

17

Thyroid & Parathyroid

Thyroid gland

Thyroxine / triiodothyronine

Metabolism regulation

Endemic goiter (iodine deficiency)

Calcitonin

Calcium uptake by bone

Parathyroid glands

Parathyroid hormone

Calcium release by bone

18

Adrenal Glands

Adrenal cortex

Cortisol

Protein breakdown

(glycolysis)

Aldosterone

Sodium reabsorption

by kidneys

Adrenal medulla

Epinephrine &

norepinephrine

Stimulates

sympathetic response 19

Quick Quiz: Which of the following

hormones is NOT involved in

regulating blood calcium levels?

A) Parathyroid hormone

B) Growth hormone

C) Calcitonin

20

Gonads

Testes

Testosterone

Sperm formation

Secondary sex characteristics

Ovaries

Estrogens

Egg maturation; uterine lining development;

secondary sex characteristics

Progesterone

Maintains uterine lining in pregnancy; development

of breast tissue

21

Pancreas

Insulin

Targets: liver, muscle

Stimulates glucose uptake

Decrease blood sugar levels

Store as glycogen

Diabetes

Glucagon

Target: liver

Stimulates glycogen breakdown (glucose release)

Raise blood sugar levels

22

Pancreatic Hormones

23

Thymus

Thymosins

Maturation of T lymphocytes

24

Quick Quiz: Which endocrine tissue

produces hormones that regulate

blood sugar?

A) Thyroid

B) Pancreas

C) Thymus

D) Testes

25