Endocrine System: Hormones and Regulation

Endocrine System Functions

• Hormones interact with specific target cells to maintain fluid, electrolyte, and acid-base homeostasis.
• Hormones promote growth and regulate metabolic processes.

Endocrine Components Defined

• Hormones interact with specific target cells to influence particular functions.
• Endocrine glands/tissues use hormones to transport signals via the bloodstream.
• Target cells have specific receptors to which hormones bind, which can change cell functions.

Hormone Transportation

• Hormones travel throughout the body via the bloodstream.
• Hormones bind only to certain receptors on target cells.

Hormone Characteristics

• Hormones are chemical messengers secreted by endocrine glands to regulate other cells.
• Hormones circulate in the bloodstream.
• Hormone concentration in the blood varies at any given moment.
• Hormones affect only target cells that have specific protein receptors.
• Hormone molecules bind to receptors with highly specific three-dimensional shapes.
• Receptors can be embedded in the plasma membrane or inside the target cell's cytosol or nucleus.

Tropic Hormones

• Tropic hormones control the secretion of other endocrine glands.

Nervous vs. Endocrine System

• The nervous system and the endocrine system differ in response time, duration, and how they use chemical messengers to communicate.

Endocrine vs Nervous System Chart

• Endocrine system uses hormones, nervous uses neurotransmitters
• Endocrine effects occur within seconds, hours, or days, nervous immediate
• Endocrine actions are longer-lasting, nervous short-lived
• Endocrine signals travel through the blood to the affect target, nervous system the target is directly effected.

Primary Endocrine Organs

• Primary endocrine organs include the anterior pituitary gland, thyroid gland, parathyroid gland, and adrenal cortices.
• The anterior pituitary gland sits in the sphenoid bone of the skull.
• The thyroid gland is in the anterior neck.
• The parathyroid gland is on the posterior side of the thyroid gland.
• The adrenal cortices are on the superior side of each kidney.

Secondary Endocrine Organs

• Secondary endocrine organs range from the heart and kidneys to the small intestines, testes, and ovaries.
• The pancreas aids in digestion.
• The thymus supports immunity.
• The hypothalamus, posterior pituitary, adrenal medulla, and pineal glands are neural.

Hormone Receptors

• Receptor location depends on the hormone's chemical structure.
• Hydrophilic hormones cannot easily cross the plasma membrane, so they interact with extracellular receptors.
• Amino-acid hormones consist of one or more amino acids; they are generally hydrophilic and bind to plasma membrane receptors, though some can be hydrophobic.
• Hydrophobic hormones can cross the plasma membrane and generally interact with intracellular receptors.
• Steroid hormones are derived from cholesterol and are hydrophobic, binding to receptors in the cytosol or nucleus.

Chemical Signal Types

• Hormones and neurotransmitters are chemical signals
• Paracrine - chemicals affect nearby but different cells, e.g., ACh in neural stimulation of muscle cells.
• Autocrine – chemicals affect the same cell or cell type, common in the immune system.
• Endocrine - uses hormones and blood stream to affect near or far cells.

Stimuli for Hormone Release

• Hormonal stimuli involve the release of a hormone caused by another hormone.
• Humoral stimuli involve a hormone secretion that increases or decreases in response to certain molecules in the blood.
• Neural stimuli involve the release of a hormone caused by signals from the nervous system.

Feedback Loops

• Negative: Homeostasis disruption detected by a receptor triggers a response that corrects the imbalance.
• Positive: Homeostasis disruption leads to a response that amplifies the disruption.

Hormone Interactions

• Maintenance of homeostasis requires multiple hormones.
• Hormones can have complementary actions, with each interacting with a different target cell.
• Synergist hormones act on the same target cell to exert the same effect.
• Antagonist hormones act on the same cells but have opposite effects.

Hypothalamus and Pituitary Gland

• The hypothalamus hypothalamus produces and releases tropic hormones to stimulate or inhibit release of anterior pituitary hormones.
• Hypothalamic-hypophyseal portal system forms a specialized blood supply, allowing hypothalamus and pituitary to deliver hormones directly to target cells.

Posterior Pituitary Hormones

• The posterior pituitary GLAND ONLY STORES, it DOES NOT MAKE HORMONES.

Antidiuretic Hormone (ADH)

• Hormone secreted by hypothalamusas and stored in posterior pituitary gland.
• ACTS ON KIDNEYS, causing water retention, which increases blood pressure.
• ADH controls water maintenance in the blood, affecting blood pressure.
• ADH insertion of water channels (aquaporins) into kidney tubule cells, promoting water uptake into the blood rather than the kidney tubules.
• Diabetes insipidus is caused by lack of ADH; results in extreme thirst and dehydration.

Oxytocin

• Produced in hypothalamus and stored in the POSTERIOR pituitary gland.
• Acts on the uterus to cause contractions, and mammary gland to release milk.
• In nursing mothers, suckling stimulates oxytocin release, causing mammary glands to contract.
• In labor it promotes contractions of the smooth muscle of the uterus.

Thyroid Stimulating Hormone (TSH)

• STIMULATES THYROID. Made in the ANTERIOR pituitary gland. Acts on thyroid to cause release of thyroid hormone.
• Development of thyroid gland and its secretions.

Adrenocorticotropic Hormone (ACTH)

• Made in the ANTERIOR pituitary gland, acts on the adrenal gland to release hormones.
• It stimulates development of adrenal gland and synthesis of steroid hormones.

Prolactin

• Made in the ANTERIOR pituitary gland, it causes milk production
• Stimulates growth of mammary gland tissue, initiates milk production after childbirth, and maintains milk production for duration of breastfeeding.
• Stimulated by hormone prolactin-releasing hormone; inhibited by prolactin-inhibiting factor (dopamine).

Luteinizing Hormone (LH)

• In males it acts on testes and females it acts on ovaries.
• Stimulates testosterone in males, and stimulates the release of estrogen and progesterone in females.

Luteinizing Hormone (LH)

• Acts on the gonads to stimulate sex hormones like testosterone, estrogen, and progesterone.

Follicle Stimulating Hormone (FSH)

• Males: Stimulates cells of testes to produce chemicals that bind and concentrate testosterone
• Females: FSH and LH together trigger estrogen production.
• FSH also triggers maturation of ovarian follicles

Growth Hormone (GH)

• Produced and secreted by anterior pituitary
• Released periodically throughout day, with peak secretion occurring during sleep
• Regulates growth of target tissues: skeletal and cardiac muscle, adipose, liver, cartilage and bone
• Action can be short or long term
• Release stimulated by growth hormone-releasing hormone (GHRH) or during exercise, fasting, stress, and protein-rich meals
• Release is inhibited by hypothalamic hormone somatostatin

Thyroid Hormone (TH)

• Secretes thyroid hormone and regulates metabolism
• The inactive form is thyroxine (T4) produced by the thyroid
• Active form = triiodothyronine (T3) – T4 is converted to T3 in tissues or organs needed
• Regulates the metabolic rate by setting a basal metabolic rate
• Promotion of growth & development bone/muscle growth and nervous system
• Affects regulation of blood pressure, heart rate, and other receptors for sympathetic signals

Calcitonin

• Thyroid gland – secretes thyroid hormone and calcitonin
• Released when calcium ion level in blood increases above normal:
• Lowers calcium level and keeps the level within normal range
• Primary target is cells in bone. Osteoclast activity is inhibited allowing osteoblast activity. Unopposed osteoblast activity reduces blood calcium ion levels as these ions are incorporated into bone matrix

Parathyroid Hormone (PTH)

• Stimulates osteoclast activity to increase calcium ion levels
• secreted in response to declining calcium ion levels in blood
• Increases calcium absorption by activating osteoclasts within the bone
• Increases absorption of dietary calcium ions by small intestine.

Aldosterone

• Released by ADRENAL GLAND. ACTS ON KIDNEYS. REGULATES SODIUM AND POTASSIUM IN THE BLOOD

Cortisol

• Glucocorticoids released from the adrenal gland; helps relieve stress.
• Long term secretions = memory loss
• Mediates the body’s stress response and regulation of glucose levels.
• Cortisol stress response (series of events that maintains homeostasis when body is faced with a stressor.)

Dopamine, Epinephrine and Norepinephrine

• STRESS HORMONES (SHORT-TERM STRESS) RELEASED BY THE ADRENAL GLANDS.
• Mediate immediate responses for fight or flight."

Androgenic Steroids

• MADE IN ADRENAL GLAND ACTS ON TESTES OR OVARIES AND CONVERTS ESTROGEN TO TESTOSTERONE AND VICE VERSA
• Affect the reproductive organs and other tissues.

Glucagon & Insulin

• Glucagon increases levels of glucose. Insulin lowers blood glucose levels by: •
• Promotes uptake and storage of ingested nutrients.
• Synthesis of glycogen in liver and synthesis of fat from lipids and carbohydrates
• Promotes satiety (feeling of fullness).

Melatonin

• Secreted by the pineal gland in the brain
• Secretes neurohormone melatonin, associated with light and dark cycles; secretion increases in dark

Testosterone

• Primary reproductive organs = testes or ovaries
• Responsible for the production of gametes
• Produces sex steroid hormones responsible for gamete and other functions
• Testes produce testosterone

Estrogen & Progesterone

• Cells of ovary produce female sex hormones, estrogen and progesterone

Atrial Natriuretic Peptide

• A peptide the heart secretes;
• ANP: Triggers relaxation of smooth muscle cells in blood vessels; increases vessel diameter (vasodilation).
• Enhances excretion of sodium ions from kidneys- an effect called natriuresis. Enhances water excretion from kidneys. Example: both vasodilation an natriuresis decrease blood volume and lower blood pressure.

Erythropoietin

• Kidneys secretes Erythropoietin (EPO) by specific kidney cells in response to decreased blood oxygen;
• EPO acts on bone marrow for new erythrocytes (erythropoiesis).

Thymosin

• Thymus found in mediastinum
• Is the site where T lymphocytes mature
• Secretes thymosin and thymopoietin, act as paracrine signals that help with T lymphocyte maturation

Gastrin

• Hormone produced by the stomach.
• A peptide hormone, it stimulates gastric acid secretion by and aids in gastric motility.
• Released by G cells in the pyloric antrum stomach, duodenum, and the pancrea
• Steroid hormones are lipid based (hydrophobic)
• Amino acid (proteins) are hydrophilic

The Heart

• Heart is defined as any condition that reduces heart's ability to function effectively as a pump: cardiomyopathy heart muscle disease, pulmonary congestion from back ups that causes pulmonary edema, Systemic Congestion backups in both/right causing perifer edema, Autorhythmicity
• CAD: decreased oxygenation known as myocardial ischemia
• Heart rate ranges: Bradycardia is below 60 bpm, Tachycardia is over 100 bpm, Normal is 60-80 bpm. Heart function
• Stroke volume (SV): is volume of blood pumped in one heartbeat
• Cardiac output (CO): is total volume of blood pumped into pulmonary and systemic circuits in 1 minute

Heart Anatomy

• Right side receives deoxygenated blood and sends it to the lungs, where it absorbs oxygen.
• Left side receives oxygenated blood from the lungs and sends it to the rest of the body.

Cardiac Circulation

Carries deoxygenated blood away towards the lungs • Pulmonary arteries of the pulmonary circuit delivers oxygen-poor and carbon. Carries Oxygen rich blood towards the heart • Pulmonary veins : delivers oxygen-rich (oxygenated) blood to left side body Oxygen/carbide dioxide exchanges • Systematic Capillaries delivers oxygen into tissues while tissue picks up carbon dioxide to be removed by the lungs.

Blood Pressure

• Pulmonary circuit is a LOW pressure system that pumps blood to the lungs.
• Systemic circuitis a HIGH pressure system That pumps blood to The body.

Anatomy of Heart

Wall of heart: pericardium, myocardium, and the endocardium

• Pericardium: connective tissue anchors heart helps to prevent chambers of chamber over filling and over stretching with vessels
• Myocardium: Cardiac cells/ myocytes/ fibro skeleton for electro activity
• Endocardium: the innermost part for the heart muscle
• Valve job: prevents black flow to one location (just to not send that blood)

Valves

Valves

• Semilunar: prevent black flow in to vesicles
• A.V/ artia: Prevent black flow into aritae Cardiac contraction/conduction system
• Pap. Muscles: attach by tendons to valve open and closing Pacemaker cells and contractile cells
• Pacemaker cells: 1% they cause action potentials the make you heart contract
• Contractile cells 99%: action for muscles cell potentials change causes reversal
• Pacemaker job: generate action potentials thereby setting pace out of heat Sound wave in hear
• S1 sound: A.V valve closed by the ventricles, and its long
• S2 sound: semilunar valve close its short Heart rate equation
• H.R = rate at which the sinoatrial node generates action potentials
• SV= all the amount of blood that is being pumped
• C.O = all of the amount of blood through systematic circulation

Pacemaker Cells

• Slow initial depolarization phase occurs more slowly due to nonspecific cation channels.
• Repolarization – After time calcium ions are gaged for closing voltage-gated start to open for potassium
• Minimal: Potassium is still open; cell is already hyper polarized- cycle restarts
• Contractions cell= rapid influx of cell is contracted.

Contractions cell

• Rapid depolarization: to the cause of sodium cell enters the cell is contracted.
• REPOLARIZATION: Sodium and calcium returns that positive ions exist muscle

Heart Rhythmic interpretation

ECG FINDING

• The whole goal to see the changes is to show electric activity if something is not connected the there will no action QRS complex
• to look at the vent depolarization T wave
• to look at vent polarization R-R interval = looking for the time of cardiac potential

A-Fib and Asytol

• A fib= ( electrical activity is hey wired and there are not contracting right)
• A fib not life threatening; normal contraction is NOT needed for vent filling Vent fib= life threatening & manifests on ECG
• Treated through electric shock-SA needs to come back and be able to deliver ( SA can be delivered )

Cardiac

cardiac- each chamber successfully and relays diastole + Sytol= cardiac contraction blood follow pre sure gradients/ valve

Vasculature System

• vasodilation/ relaxation increases length
• vasoconstriction / decreases length
• amount a blood flow per - Blood flow: minute ( C.O)
• the resistance for blood flow inside the vasculature ( resistance) / ( slow the speed) Hydro pressure: of the blood vessels ( high fluid)
• Ostomotic pressure: follows the water if their salt and the move the it that is in its container

Vessel Function

• Vessel layers- inner-most / the epithelium provides and smooth surface; outer-most/ provide for tissue/ prevent its from over stretching)
• Muscle Contraction provide with autonomies/ smooth contract that goes thru the body but not over stretching the vasum that connects all the vessels Vasoreceptors detects blood of different cells vessels

Vessels

1- Elastic / they have the high amount of pressure and its close to the body 2- Muscular arteries/ supplies each a organs cells 3- Arteries Smallest delivers to the capillary beds/ capillaries deliver through tissue-classified on appearances/ continious- and small can move

Vasculature and the heart relationship : Veins returns blood to the heart, the have a lot to and for blood to to body

Anastomoses vs Arteriole

• Anastomoses /the convergence of the heart more then one route Arteriole Shunt/ ( the rerouting of the bypass / but is DANGEROUS to the artery heart) the vessels in side the body / it is rerouted the vessel the it goes a capillary blood to reach the a organs or destination

4 key Factors for Resistance

1- Vessel = dilation/radius is the vessel of the radius ( vasal distention ) 2- Blood Viscosity Increase viscosity blood preuress for thickness ( plasma / cell) 3-Length the longer the the preure and increase is ( physical blockage - 4-CO heart function/ stroke

• If resistance increases, then pressure increase/ if resistance decreases and pressure decreeses*
• If C.O increases blood pressure increases / that blood is being ejected and being supplied*

If Blood Volme, Water, Vessel

( is the amount of blood or water)

• if water increases blood increases / the pressure for vessel will go* Vessle press: Arteries high pressure in capillaries

Pressure

Hydo : push out on the walls osto: draws blood into and out

• Venues return blood but low key no pressure: venous and skeletal help squeeze with with contraction*

Arteries

• Carotid - deliver oxygen to the brain liver, splenic, & intereric - all supply blood to there respective organs or regions*

Superior / Inferior Vena vasa - supply

• superior goes form head torso / and inferior lower Torso to the a heart, where it supply*
• Veins carry of blood from a lungs / arteries transport to lungs / and is common to mix up*