Anatomy

Which system?
Hormones released into the bloodstream travel throughout the body

Releases neurotransmitters excite or inhibit nerve, muscle & gland cells

Which system?
Results in milliseconds, brief duration of effects

Which system?
Results may take hours but last longer

Only affect target cells with specific membrane proteins called receptors

Constantly being synthesized & broken down
A range of 2000-100,000 receptors / target cell

Excess hormone, produces a decrease in number of receptors
-receptors undergo endocytosis and are degraded– Decreases sensitivity of target cell to hormone

Deficiency of hormone, produces an increase in thenumber of receptors
Target tissue more sensitive to the hormone

Both are master endocrine glands since their hormones control other endocrine glands

Receives input from cortex, thalamus, limbic system & internal organs

Connected to the pituitary gland by a stalk called the infundibulum

Pea-shaped gland found in sella turcica of sphenoid

Infundibulum attaches it to brain

Anatomy of Pituitary Gland:
75%
Connected to hypothalamus by portal veins

Anatomy of Pituitary Gland:
25%
Ends of axons of neurons found in hypothalamus
Stores and releases neurotransmitter/hormones intoblood strea

What are the 3 steps of flow of blood to anterior pituitary?

ANTERIOR PITUITARY (ADENOHYPOPHYSIS):
What are the 7 major hormones secreted by 5 cell types?

Produced by somatotrophs

Common target cells are liver, skeletal muscle, cartilage and bon

Increases cell growth & cell division by increasing their uptake of amino acids & synthesis of proteins

Produces Thyroid Stimulating Hormone (TSH)

Stimulates the synthesis & secretion of T3 and T4 from thyroid gland
Metabolic rate stimulated

What releases Follicle Stimulating Hormone?

1. initiates the formation of follicles within the ovary
2. stimulates follicle cells to secrete estrogen
3. stimulates sperm production in testes

Produces Luteinizing Hormone (LH)

What hormone stimulates this in females:
-Secretion of estrogen
-Ovulation of 2nd oocyte
-Formation of corpus luteum
-Secretion of progesterone

In males, stimulates interstitial cells to secrete testosterone

Produce prolactin

Causes milk production
Function in males not known

Secrete adrenocorticotrophichormone (ACTH)

Stimulates cells of the adrenal cortex that produce glucocorticoids

Secreted by corticotrophs

Function not certain in humans (increase skin pigmentation in frogs)

Does not synthesize hormones

Consists of axon terminals of hypothalamic neurons

Neurons release two neurotransmitters that enter capillaries
– antidiuretic hormone
– oxytocin

Also known as vasopressin

Functions (response to low BP)
– decrease urine production
– decrease sweating
– increase BP
– increased thirst

Two target tissues both involved in neuroendocrine reflexes

Which hormone?
During delivery– baby’s head stretches cervix– hormone release enhances uterine muscle contraction– baby & placenta are delivered

Which hormone?
After delivery– suckling & hearing baby’s cry stimulates milk ejection– hormone causes muscle contraction & milk ejection

On each side of trachea is lobe of thyroid gland joined by isthmus

Consists of follicular cells surrounding follicle filled with precursor substance (thyroglobulin), active form is called thyroid hormone, T3 or T4

What are the 3 Thyroid hormone functions?

Histology of Thyroid Gland:
Sac of stored hormone (colloid) surrounded by follicular cells that produced it

Histology of Thyroid Gland:
In between cells

Produce calcitonin
Decreases blood calcium levels by decreasing activity of osteoclasts and excretion by kidneys

Oxyphil cell function:

What do Principal cells produce?

Increase activity of osteoclasts
Increases reabsorption of Ca+2 by kidney
Promote formation of calcitriol (vitamin D) by kidney and liver which increases absorption of Ca+2 by intestinal tract

Opposite function of calcitonin

One on top of each kidney

Which cortex produces 3 different types of hormones from 3 zones of cortex?

Which medulla produces epinephrine & norepinephrine?

What are the 3 structural parts of the adrenal gland?

Secreted in response to low blood pressure, signals kidney to absorb more Na+ and water

Secreted in response to stress, raises blood sugar levels also used as an anti-inflammatory agent (over use reduces immune response)

Have masculinizing effects

Adrenal Medulla:
Receive direct innervation from sympathetic nervous system
– develop from same tissue as postganglionic neurons

Produce epinephrine & norepinephrine

Hormones are sympathomimetic
– effects mimic those of sympathetic NS
– cause fight-flight behavior

Organ consists of head, body & tail

Which organ:
Cells (99%) in acini produce digestive enzymes (exocrine part)

Cells in pancreatic islets that produce hormones (islets of Langerhans)

Cells that surround a small duct in the pancreas

Cell organization in pancreas:
Cells that secrete near a capillary

Cell Types in the Pancreatic Islets:
Produce glucagon (increases blood sugar levels)

Cell Types in the Pancreatic Islets:
Produce insulin (decreases blood sugar levels)

Cell Types in the Pancreatic Islets:
Produce somatostatin (reduces secretions of alpha and beta cells)

Cell Types in the Pancreatic Islet:
Produce pancreatic polypeptide (inhibits activity of exocrine part of pancreas)

Estrogen, progesterone, relaxin & inhibin
Regulate reproductive cycle, maintain pregnancy & prepare mammary glands for lactation

Interstitial cells produce testosterone
Regulate sperm production & 2nd sexual characteristics

Small gland attached to 3rd ventricle of brain
Consists of pinealocytes & neuroglia

Pineal Gland:
Responsible for setting of biological clock

Pineal Gland:
Treatment is bright light

Pineal Gland:
Hyperactive person (high sympathetic activity)

Effect of Light on Pineal Gland:
_________secretion producing sleepiness occurs during darkness due to lack of stimulation from sympathetic ganglion

Depression that occurs during winter months when day length is short
Due to overproduction of melatonin

Due to overproduction of melatonin

Therapy for SAD and Jet Lag

Important role in maturation of T cells in infants and children
Hormones produced by gland promote the proliferation & maturation of T cells

4 hormones produced by thymus gland: