A&P 2 Exam 1

The difference between neurotransmitter and endocrine system

NS- releases NT, close to site of release and binds receptors in postsynaptic membrane
Endocrine system- releases hormones, circulates through the blood and bind to receptors on or in target cells

Target cells

Cells that have receptors for a given chemical

Types of target cells for NS and Endocrine system (ES)

NS- Muscle fibers (all 3) gland cells and neurons
ES- Cells throughout the body

Time to onset of action for NS and ES

NT- Typically within milliseconds
ES- seconds to hours or days

Duration of action for NS and ES

NS- Brief (milliseconds)

ES- Longer (seconds to days)

Site of actions for NS and ES

NS- Close to site of release

ES- far from site of release

Exocrine Glands

Secretes their products onto the surface of the body or into the lumen of a hollow organ (Ex: stomach, mouth, airways…)
They are NOT hormones

What does the Exocrine glands include?

• sudoriferous (sweat) glands

• sebaceous (oil) glands

• mucous glands

• digestive glands

What do endocrine glands secrete?

Hormones directly into interstitial fluid and bloodstream. They DO NOT have ducts

Endogrine glands include what glands?

• Pituitary

• thyroid

• parathyroid

• adrenal

• pineal glands

What gland is both endocrine and exocrine?

The pancreas is both an endocrine and exocrine gland, as it produces hormones such as insulin and digestive enzymes.

Examples of secreting cells?

• Hypothalamus

• Thymus

• Pancreas

• Ovaries

• Testes

• Kidneys

• stomach

• liver

• Small intestine

• skin

• heart

• Adipose tissue

• Placenta

What hormone does the skin (organs) secrete?

Cholecalciferol

What role does Cholecalciferol do?

Plays a role in the synthesis of calcitriol, the active form of vitamin D

What hormone or hormones does the digestive canal (organ) secrete?

• Gastrin

• Glucose-dependent insulinotropic peptide

• Secretin

• Cholecystokinin

What does the hormone Gastrin do?

Promotes the secretion of gastrin juice; increases movement of the stomach

What does the hormone Glucose-dependent insulinotropic peptide (GIP) do?

stimulates the secretion of pancreatic juice and bile

What does the hormone Secretin do?

stimulates secretion of pancreatic juice and bile

Cholecystokinin (CCK)

stimulates the secretion of pancreatic juice; regulates the release of bile from the gallbladder and causes the feeling of fullness after eating

What hormones does the placenta (organ) secrete?

• Human Chorionic gonadotropin (hCG)

• Estrogen and progesterone

• Human chorionic somatomammotropin (hCS)

What does the hormone Human Chorionic gonadotropin (hCG) do?

stimulates corpus luteum in ovary to continue production of estrogen and progesterone to maintain pregnancy

What does the hormones Estrogen and progesterone do?

Maintain pregnancy, help prepare mammary glands to secrete milk

What does the hormone Human chorionic somatomammotropin (hCS) do?

stimulates development of mammary glands for lactation

What hormones does the Kidneys (organ) secrete?

• Renin

• Erythropoietin (EPO)

• Calcitriol (active form of vitamin D)

What does the hormone Renin do?

Helps raise the blood pressure by bringing about vasoconstriction and secretion of aldosterone

What does the hormone Erythropoietin (EPO) do?

increases rate of RBC formation

What does the hormone calcitriol do?

aids in the absorption of dietary calcium and phosphorus

What hormone(s) does the heart (organ) secrete?

Atrial natriuretic peptide (ANP)

What does the hormone Atrial natriuretic peptide (ANP) do?

Decreases BP

What are the 4 things to consider to see the activity of a hormone?

• the hormone

• the hormone’s receptors

• the chemical nature of the hormone

• the interaction between the hormones and other hormones

what does the hormone affect when traveling throughout the body?

Target cells that posses specific protein receptors for the hormone

Receptors are continually…?

being synthesized and broken down

What are the two regulated receptors?

• down-regulated

• up-regulated

Down-regulated receptors

are receptors that decrease in number or sensitivity in response to high levels of a hormone.

found in the presence of high concentration of hormones

Up-regulated receptors

are receptors that increase in number or sensitivity in response to low levels of a hormone.

found in the presence of low concentration of hormones

Endocrine have target cells that are close or far from site of release?

far away from site of release

What are the two location types for target cells?

• Paracrines

• Autocrines

Paracrines

Affects nearby cells

Autocrines

Affect the same cell that released them

What are lipid-soluble hormones

• Steroid hormones

• Thyroid hormones

• Gas

What are examples of steroid hormones

• Cortisol

• Testosterone

• Estrogen, progesterone

• Calcitriol

What are examples of thyroid hormones

T3 and T4

What are examples of lipid-soluble gas?

Nitric oxide (NO)

What are water-soluble hormones

• Amines

• Peptides and proteins

What are example of Amines?

• Epinephrine, norepinephrine

• histamine

• melatonin

• serotonin

What are examples of Peptides and proteins

• Insulin

• Glucagon

• Growth hormone

• Oxytocin

• All hypothalamic releasing and inhibiting hormones

What are some responses that a hormone may have?

• Synthesis of new molecules

• Changing permeability of the cell membrane

• stimulating transport of a substance into or out of the cell

• Altering the rate of metabolic actions

• causing contractions of smooth or cardiac muscle

Lipid-soluble Hormone mechanism of hormone action

• Hormone is transported through blood via a transport protein

• Transport protein will release hormone close to target cell

• Hormone then diffuses INTO the target cell

• Hormone will bind to receptor INSIDE the cell

• The activated receptor-hormone complex alters gene expression

• This leads to new proteins being made or proteins no longer being made directed by newly formed mRNA

• The new protein alters cell activity

Water-soluble hormone mechanism of hormone action

• Travels in a free or unbound state in the blood

• Receptors are located IN the Plasma Membrane

• The binding of hormone (first messenger) to its receptor activates G protein which then activates adenylyl cyclase

• activated adenylyl cyclase converts ATP to cAMP

• cAMP serves as a second messenger to activate protein kinases

• activated protein kinases phosphorylate cellular proteins

• millions of phosphorylated proteins causes reactions that produce physiological responses

• Phosphodiesterase inactivates system by breaking cAMP

What is the first messenger (water soluble hormone)

Binding of hormone

What is activated once the hormone binds to its receptor (water soluble hormone)

G protein which activates adenylate cyclase

Where is the receptor located at? (water soluble hormone)

located in the plasma membrane

What does the activated adenylate cyclase do? (water soluble hormone)

converts ATP to cAMP (cyclic AMP)

What is the second messenger? (water soluble hormone)

cAMP

What does cAMP do? (water soluble hormone)

It activates protein kinases, which then phosphorylate other proteins

What does phosphodiesterase do? (water soluble hormone)

inactivates the system by breaking cAMP

What are the three relationship of hormones?

• permissive effect

• Synergistic effect

• Antagonistic effect

Permissive effect

(think permitting)

Hormones work more effectively when a second hormone is present to assist them (T3/T4)

Synergistic effect

Hormones with similar functions to others work together to produce a greater effect than either hormone alone. (luteinizing hormone and estrogen)

Antagonistic effect

(enemies)

Some hormones oppose the actions of others (insulin and glucagon)

Secretion is regulated by?

• Signals from NS

• chemical changes in the blood

• other hormones (tropic hormones)

• Feedback loops

  • most are negative but some like oxytocin are regulated by positive feedback

What two glands work together?

hypothalamus and pituitary gland

What gland is the only link between the NS and ES

Hypothalamus

What are the hypothalamus and pituitary gland connected by?

infundibulum

What does the hypothalamus control?

release of hormones from the pituitary gland

What lobe makes up 75% of the weight in the Pituitary gland?

Anterior lobe (adenohypophysis) that also secretes 7 hormones

What lobe releases two hormones and made by the hypothalamus?

neurohypophysis (posterior lobe)

What does the hypothalamus secretes?

Releasing and inhibiting hormones that control the release of hormones by the pituitary gland

How does these hormones reach the pituitary gland?

hypophyseal portal system

What are the 5 cell types in the anterior pituitary

• Somatotrophs

• thyrotrophs

• Gonadotrophs

• Lactotrophs

• Corticotropes

What hormone(s) does the cell somatotrophs release?

Growth hormone (GH)

What hormone(s) does the cell Thyrotrophs release?

Thyroid-stimulating hormone (TSH)

What hormone(s) does the cell Gonadotrophs release?

Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH)

What hormone(s) does the cell Corticotrophs release?

Adrenocorticotropic hormone (ACTH) and Melanocyte-stimulating hormone (MSH)

Growth hormone (GH) what are the stimulating and inhibiting hormone

GHRH for growth hormone releasing hormone (somatocrinin)

GHIH for growth inhibiting hormone (somatostatin)

Thyroid stimulating Hormone (TSH) what are the stimulating and inhibiting hormone

TRH- thyrotropin releasing hormone

GHIH- growth hormone inhibiting hormone

Follicle-stimulating hormone (FSH) what are the stimulating and inhibiting hormone

Stimulating hormone: GnRH (gonadotropin-releasing hormone)

Luteinizing hormone (LH) what are the stimulating and inhibiting hormone

Stimulating hormone: GnRH (gonadotropin-releasing hormone)

Prolactin (PRL) what are the stimulating and inhibiting hormone

Stimulating hormone: PRH (prolactin-releasing hormone)

Inhibiting hormone: PIH (prolactin-inhibiting hormone)- dopamine

Adrenocorticotropic hormone (ACTH) what are the stimulating and inhibiting hormone

Stimulating hormone: CRH (corticotropin-releasing hormone)

Melanocyte-stimulating hormone (MSH) what are the stimulating and inhibiting hormone

Stimulating hormone: CRH (corticotropin-releasing hormone)
Inhibiting hormone: Dopamine

Growth Hormone (GH) Target tissue and action?

Target tissue is the Liver

Action: stimulates liver, muscle, cartilage, bone and other tissues to synthesize and secrete insulin-like growth factors (IGFs) which promotes growth of body tissues. It enhances lipolysis and decreases glucose uptake

Thyroid stimulating hormone (TSH) Target tissue and action?

Target: Thyroid gland

Action: stimulates synthesis and secretion of thyroid hormone by thyroid gland

Follicle-stimulating hormone (FSH) Target tissue and action?

Target: Ovary and Testis
Action:
in females- initiates development of oocytes and induces ovarian secretion of estrogen
in males- stimulates testes to produce sperm

Luteinizing hormone (LH) Target tissue and action?

Target: Ovary and Testis
Action:
in females- initiates secretion of estrogen and progesterone, ovulation and formation of corpus luteum
in males- stimulates testes to produce testosterone

prolactin (PRL) Target tissue and action?

Target: Mammary glands


Action: promotes milk production in females.

Adrenocorticotropic (ACTH) Target tissue and action?

Target tissue: Adrenal cortex
Action: stimulates secretion of glucocorticoids (cortisol) by adrenal cortex

Melanocyte-stimulating hormone (MSH) Target tissue and action?

Target: Brain

Action: unknown exact role but when present in excess can cause darkening of skin

Negative feedback controls the secretion of what cells?

Thyrotrophs

gonadotrophs

corticotrophs

GH

• causes growth and repair of tissues

3 major changes that IGF’s do

• Increased protein synthesis (building blocks)

• increased lipolysis (energy for growth)

• increased blood glucose levels by decreasing the uptake of glucose by other cells (energy for brain)

What controls GH release

• hypoglycemia to GHRH release from hypothalamus

• released from anterior pituitary

• leads to elevation of blood glucose

• glucose levels normalized- GHIH is released to stop GH release

• Hyperglycemia leads to inhibition of GH release

What are the three GH disorders?

• Pituitary dwarfism= hyposecretion of GH in childhood

• Giantism-- excess secretion of GH in childhood

• Acromegaly- excess secretion of GH in adulthood, leads to diabetogenic effect

Posterior Pituitary hormones

• Does NOT synthesize hormones but stores and release from axon terminals that are produced by the neurosecretory cells of the hypothalamus

Posterior Pituitary 2 hormones

• Oxytocin (OT)

• Antidiuretic hormone (ADH)

What does the axons form the neurosecretory cells form the what tract?

Hypothalamic-hypophyseal tract

Oxytocin (OT)

• released in response to the stretch being place on the cervix during childbirth

• it affects the uterus and breaks

• uterus- enhances contractions

• breasts- STIMULATES milk ejection

Antidiuretic hormone (ADH)

Also known as Vasopressin

• increase in BP

What is the mechanism of action for Antidiuretic hormone (ADH)

• causes an increased water reabsorption by kidney; decreases urine formation

• causes decreased activity of the sweat glands

• causes vasoconstriction

Control of secretion in Antidiuretic hormone (ADH)

• secreted in response in blood osmotic pressure

• too little solute= osmotic pressure is low = ADH will not be secreted= urine formation

• too much solute= osmotic pressure is high = ADH is released= less urine formation to conserve water