Medicina

The endocrine system can be broken down into signal senders, the signals they send, and the signals’ outcomes. The main signal senders are the endocrine glands, which include the hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, and gonads (ovaries and testicles). Endocrine glands specifically send chemical signals to different parts of the body. These chemical signals, which are hormones, generally cause slower, subtler changes than the nervous system, which uses electric signals.

The signals travel through the rest of the body via the bloodstream, but only the intended cells in the body respond to these hormonal signals. These cells are keyed with receptors that fit with the hormone—just like two matching puzzle pieces. The hormone then signals the cell to perform a desired job, such as releasing another hormone, releasing or taking in nutrients, or changing the speed at which the body makes certain proteins.

The end result is that the endocrine system can adjust the levels of nutrients in the blood, excrete excess nutrients, help the body respond to its environment, and direct growth and development. For example, the pancreas secretes hormones that help the body control the level of sugar in the blood. The adrenal glands, thyroid gland, and parathyroid gland keep critical minerals like calcium and sodium in balance. The adrenal glands also make hormones for the fight-or-flight response to danger. Growth hormone helps the body grow to adult height and affects metabolism. The gonads make hormones that help drive sexual development. The endocrine system even stimulates milk production in new mothers.

The glands are linked to the nervous system via the hypothalamus. It gets its name from its location in the brain, resting just below the thalamus. While part of the brain, the hypothalamus also acts as a gland in that it makes and releases hormones that direct the other glands. The main role of the hypothalamus is to direct the activity of the pituitary gland. It can cause the pituitary to make and release its chemical signals via chemicals called releasing hormones (example: gonadotropin-releasing hormone).

The pituitary gland is made of two parts: the anterior (front) and posterior (back) pituitary. The anterior pituitary gland is the origin for many very important hormones. These hormones travel by blood and stimulate many other endocrine glands, including your thyroid gland, adrenal glands, and gonads.

Located in the front part of your neck resting just below the Adam’s apple is your thyroid gland and just behind it, the parathyroid glands. The thyroid gland makes hormones (T3 and T4) that affect the body’s metabolism, as well as a hormone that helps control the level of calcium in the blood. The parathyroid glands also make a hormone that works along with the thyroid hormone to control the blood’s calcium level.

The pancreas, an interesting gland that sits just under your stomach, is both an endocrine gland and a gastrointestinal organ. As an endocrine gland, it sends hormones directly into the bloodstream that help keep the blood sugar level in balance. As a gastrointestinal organ, it secretes enzymes by ducts (exocrine) directly into your intestines to help with digestion.

The adrenal gland gets its name from its location in your body, as it lies on top of your kidneys. The adrenal gland has an inner layer that makes the fight-or-flight hormone, adrenaline. Its outer layer, or cortex, makes two general types of hormones. One type keeps mineral levels in balance and also maintains the proper volume of water and salt in the blood. The other helps keep blood sugar levels in balance and affects your body’s response to inflammation.

gland- aden/o

adrenal gland- adren/o, adrenal/o

outer surface- cortic/o

 gonads (sex organs)-gonad/o

pancreas-pancreat/o

pituitary gland- pituitar/o, hypophys/o

thymus- thym/o

thyroid-thyr/o, thyroid/o

 sugar-gluc/o, glucos/o, glyc/o

  to secrete-crin/o

  hormone- hormon/o

  ketone body-  ket/o

stimulating hormone- -tropin

blood condition-emia

  urine condition-uria

arche-begining

meno-menstrual

a-no

em-blood

ic-pertaining to

phag-eat

acro-extremities

ex-out

acid-acid

alkal-alkali

chlor-chloride

eu-good

kal-potassium

natr-sodium

keton-ketone

renal-kidney

ine-chemical

epi-upon

trop-stimulating

megaly-enlargament

genesis-formation

neo-new

meta-over

bowl-throw

chol-bile

angio-vassel

dys-bad

plasia-formation

con-with

genit-birth

lith-stone

iasis-presence

pan-all

toxic-poison

para-beside

ACTH-adrenocorticotropic hormone

BS-blood sugar

CGM-continuous glucose monitor

DI-diabetes insipidus

DM-diabetes mellitus

ERCP-endoscopic retrograde cholangiopancreatography

FBS-fasting blood sugar

GDM-gestational diabetes mellitus

GH-growth hormone

GTT-glucose tolerance test

HgA1C-hemoglobin A1C test (used by diabetes patients to monitor blood sugar levels)

HRT-hormone replacement therapy

TFT-thyroid function test

TSH-thyroid-stimulating hormone (also known as thyrotropin)

T3-triiodothyronine (one of two primary hormones produced by the thyroid)

T4-thyroxine (one of two primary hormones produced by the thyroid)

Blood has three main types of cells (cytes). Red blood cells (erythrocytes) are the transport trucks that bring oxygen to all the cells of the body and take away the waste. White blood cells (leukocytes) fight infection. Platelets (thrombocytes) are the small scab-makers of the body. They patch things up.

Red blood cells are the most common cells in the blood (hemo/hemato). They contain a substance called hemoglobin. Hemoglobin grabs on to oxygen when the surrounding oxygen levels are high and releases it when the ambient oxygen levels are low. In this way, it helps carry fresh oxygen from the lungs to all the parts of the body that need it.

White blood cells protect the body from invasion. The blood contains different types of white blood cells that fight different types of infections (neutrophils, lymphocytes, basophils, and eosinophils). Each carries out a different job.

Platelets are the smallest of the cells in the blood. Their job is to patch up any broken blood vessels. Blood vessels constantly develop small leaks. They need a patch system to keep them functioning properly. When a vessel is injured, it attracts platelets that clump together to form a sticky patch. They also send signals that help further form a permanent clot.

clot-thromb/o

blood-hem/o, hemat/o

cell-cyt/o

 white-leuk/o

vein-  phleb/o, ven/o

 lymph-lymph/o

 blood condition–emia

  tonsils-tonsill/o

edema- swelling

iso-equal

ellipto-oval-shaped

cyte-cell

embol-embolus

em-in

erythro-red

poiesis-formation

lysis-breakdown

macro-large

myelo-bone marrow

trombo-clot

malacia-softening

globin-globe

immuno.immune system

gram-recod

per-trough

tom-cut

mano-thin

sphygmo-strangle

isch-hlod back

bili-bile

septic-rotting

ectasia-dilatation

static-standig

neproh-kidney

apheresis-separation

AIDS-acquired immunodeficiency syndrome

ALL-acute lymphoblastic leukemia

AML-acute myeloid leukemia

BMT-bone marrow transplant

CBC-Complete blood count

CML-chronic myeloid leukemia

DIC-  disseminated intravascular coagulopathy

EBV-  Epstein-Barr virus

ESR-erythrocyte sedimentation rate

Hct-hematocrit

Hgb-  hemoglobin

HIV-  human immunodeficiency virus

HSM-  hepatosplenomegaly

HUS-  hemolytic uremic syndrome

INR-  international normalized ratio

ITP-  idiopathic thrombocytopenic purpura

IVIG-  intravenous immunoglobulin

LAD-lymphadenopathy

PLT-platelet count

PTT-  partial thromboplastin time

RBC-  red blood count; red blood cell  

TTP-thrombotic thrombocytopenic purpura

WBC-white blood count; white blood cell

The left side of the heart handles oxygen-rich blood, and the right side handles the oxygen-poor blood. A thick wall of muscle, the septum, divides the left and right sides.

On the left side, the mitral valve connects the left atrium and ventricle. Then the aortic valve connects the left ventricle to the outgoing blood vessel, the aorta. On the right side, the connector between the atrium and ventricle is the tricuspid valve. The pulmonary valve connects the right ventricle and the outgoing blood vessel, the pulmonary artery.

Circulation

There are miles of blood vessels in the body. From vessels the size of a garden hose down to tiny capillaries much thinner than a human hair, blood vessels make up a large transportation network that acts like a road system. This system is a closed loop.

The left ventricle forces blood into the main outgoing vessel (aorta). The aorta branches into smaller arteries, just as highways have exits to smaller roads. These branches break off further still. Eventually, they reach their destinations: the brain, stomach, muscles, and so on.

By this point, the blood is flowing in tiny vessels known as capillaries. The oxygen and other nutrients pass out into the tissues that need it, and they give back their waste.

Once the blood has made the delivery and picked up the waste, it begins its journey back to the heart through veins. Smaller veins collect into larger veins, which collect into the upper (superior) and lower (inferior) vena cava. These main veins return blood to the right atrium.

Page 512At the same time that the left ventricle pumps blood into the aorta, the right ventricle pumps blood into the pulmonary artery. The pulmonary artery carries blood to the lungs to attain oxygen and discard carbon dioxide. Once these gases are traded, the blood returns to the heart through a system of veins that lead to the main pulmonary vein. The pulmonary vein dumps the oxygen-rich blood into the left atrium. When the valve opens between the left atrium and left ventricle, the blood fills the ventricle and the cycle continues.

The most common heart problem patients report is chest pain (pectoralgia). The causes can range from minor issues, like muscle soreness, to the pain associated with a heart attack (angina pectoris). Patients can occasionally feel pain in their blood vessels. This is most common with enlarged surface veins (phlebalgia).

While the heart never stops beating, we are rarely aware of its rhythm. When the heart beats out of pace, a patient might feel a jumping sensation (palpitation). If the heart continues to beat in an odd rhythm (arrhythmia, dysrhythmia), a patient may notice this as well.

When a patient’s heart muscle fibers are contracting and sending blood out of the ventricles, the pressure in the arteries is at its highest. This arterial pressure, the systole, is the first number of a blood pressure reading.

The second number of a blood pressure reading is called the diastole. It refers to the pressure on the vessels when the heart is relaxed and filling with blood. 

Chief among the means of evaluating the heart is listening directly to the heartbeat. There are two heart sounds that are caused by the closing of valves in the heart. The first heart sound (S1) is due to the closing of the valves between the atria and ventricles. This represents the beginning of heart contraction (systole). Systole ends with closing of the pulmonary and aortic valves, which creates the second heart sound (S2). When listening to the heart, the examiner listens for abnormal sounds (murmurs) or a disturbance in the rhythm.

  valve-valvul/o

  vessel-angi/o, vas/o, vascul/o

  aorta-aort/o

fatty plaque-ather/o

rrhythm-rhythm

phoresis-carry

dia-through

rrhage-burst forth

ium-tissue-

card-heart

epi-upon

myo-muscle

brady-slow

cyan-blue

cava-hollow

scler-hard

arterio-artery

athero-fatty plaque

sono-sound

sys-together

stol-send

re-back

an-up

tens-strech

ton-tone

vers-turn

thorac-chest

stom-mouth

rraphy-suture

varico-swolen