Lab 2: The Endocrine System and Blood

Endocrine glands

Glands that secrete hormones directly into the bloodstream.

Exocrine glands

Glands that secrete substances through ducts to the outside of the body.

Hormone

Chemical messengers that act on target cells, tissues, or organs.

Endocrine gland

Glands that release hormones directly into the bloodstream.

Exocrine gland

Glands that secrete substances through ducts.

Pineal Gland

Produces melatonin.

Hypothalamus

Controls hormone release by secreting stimulating and/or inhibiting hormones.

- Also controls non-endocrine functions such as pH, hunger, thirst, etc...

Pituitary Gland

Also known as Hypophysis; connected to the hypothalamus by the infundibulum.

- Anterior lobe: endocrine tissue

- Posterior lobe: nervous tissue

Adenohypophysis

Anterior lobe of the pituitary gland; composed of endocrine tissue (simple cuboidal).

Neurohypophysis

Posterior lobe of the pituitary gland; composed of nervous tissue.

- Hormones stored here are synthesized in the hypothalamus

Follicular cells

Produce T3 and T4, dark cells surrounding thyroid follicles

Thyroid Gland

Produces thyroid hormone (T3 and T4) and calcitonin.

Function of thyroid hormones

regulate metabolism

Function of calcitonin

- Lowers blood calcium levels

- Increase bone density

Mainly in children

T3

triiodothyronine

T4

thyroxine (tetraiodothyronine)

Isthmus (thyroid)

tissue connection between right and left thyroid lobes

Parafollicular cells

AKA "C cells"

- Produce calcitonin (lower blood calcium)

- Located outside the thyroid follicles

Parathyroid Glands

Usually 4 glands located bilaterally on the posterior of the thyroid gland that produce parathyroid hormone.

- Raise blood Ca2+ levels

Thymus

Known as the 'shrinking' gland; produces thymosins.

- Huge in childhood, shrinks at adulthood

Thymosins

Part of the immune system

Hormone produced by the thymus responsible for T-lymphocyte development and function

Pancreas

Located posterior to the stomach

Has both endocrine and exocrine functions:

Endocrine: (produces insulin and glucagon)

Exocrine: (produces pancreatic juice for digestion).

Pancreatic islets (islets of Langerhans)

Endocrine cells that produce insulin and glucagon in the pancreas

Acinar cells

Exocrine cells that secrete digestive enzymes through ducts in the pancreas

- Dumps juice into the small intestine

Adrenal Glands

Composed of cortex (external) and medulla (internal).

Adrenal Cortex

Produces corticosteroid hormones for water and electrolyte balance and metabolism. Also produces androgens and estrogens

Adrenal Medulla

Produces epinephrine and norepinephrine for stress response.

Testes

Have endocrine (produce testosterone) and exocrine functions (produce sperm).

Seminiferous tubules (testes)

Exocrine glands that produce sperm

- Large circular structures that contain many individual tubules

Interstitial cells (testes)

Endocrine cells that produce testosterone

- Smaller circular structures located outside the semin. tubules

Ovaries

Have endocrine (produce estrogen and progesterone) and exocrine functions (produce follicles which contain eggs (oocyte)).

Ovarian follicle

developing sac enclosing each ovum (egg) within the ovary

- Contain granulosa cells which produce estrogen and progesterone

Granulosa cells

Endocrine cells in an ovary surrounding the egg that produces estrogen and progesterone

Mixed glands

Testes, ovaries, and pancreas

- Both endocrine and exocrine

Blood

Connective tissue with a pH of 7.35-7.45, composed of plasma (~55%) and formed elements (~45%).

Blood Alkalosis

blood pH above 7.45

Blood Acidosis

Blood pH below 7.35

Blood Plasma

Over 90% water

10% proteins such as albumin, globulin, and fibrinogen, along with electrolytes, hormones, gases, nutrients, and wastes.

Function: Transport of plasma components and formed elements

Which protein found in blood plasma is key in coagulation?

Fibrinogen

Blood formed elements

erythrocytes, leukocytes, thrombocytes

Erythrocytes (RBC)

Red blood cells containing hemoglobin; average count is 4.2-6.2 million/uL.

Shape:

- biconcave (due to lack of nucleus)

non-nucleate

- This causes RBC's to be the smallest formed element

Function:

- Transport oxygen to body cells (key in ATP synthesis)

- Picks up CO2 for disposal

Thrombocytes (platelets)

Average count is 150,000-360,000 per uL

Function:

- Blood coagulation

Non-nucleate

- Cells fragments

Leukocytes (WBC)

White blood cells; average count is 5,000-10,000 per uL.

Cell category types:

- Granulocytes: Visible granules

- Agranulocytes: non-visible granules

5 types:

- Neutrophils

- Eosinophils

- Basophils

- Lymphocytes

- Monocytes

Function:

- Immune support, kill foreign invaders

Granulocytes

Type of leukocyte that contain visible granules

neutrophils, eosinophils, basophils

All end in -phils

Agranulocytes

Non-visible granules

lymphocytes and monocytes

Neutrophils

Most common Granulocyte

Form/identification:

- Always 3-5 lobes/structures inside of nuclei

Function:

- phagocytosis of bacteria

Eosinophils

Granulocyte with red/pink cytoplasm (red granules)

Function

- Fighting parasites and phagocytosis of allergens

Basophils

Most rare granulocyte

Form/Identification:

- Large, dark granules

- Can't see cytoplasm or nucleus

Function:

- secrete histamine and heparin

- allergic and inflammatory responses

Lymphocytes

Agranulocyte, second most common leukocyte

Form/Identification:

- Small cells with large, round nucleus;

Two Types:

- T-lymphocytes (T-cells): destroy foreign cells

- B-lymphocytes (B-cells): produce antibodies

T-cells

Type of lymphocyte (agranulocyte)

Cells created in the thymus that produce substances that attack infected cells in the body.

B-cells

Type of lymphocyte (agranulocyte)

Cells made in the bone marrow that create antibodies

Monocytes

Agranulocyte

Form/identification:

- Large cells with kidney-shaped nucleus;

Function:

- Involved in phagocytosis and become macrophages

Blood pressure

Pressure that your blood exerts on the vessels as it travels

Measured in mmHg; normal resting blood pressure in a young adult is typically around 120/80 mmHg.

Normally measured on the brachial artery

Pulse pressure

Measured in mmHg;

calculated as systolic pressure minus diastolic pressure.

Mean arterial pressure (MAP)

Measured in mmHg;

calculated as (pulse pressure ÷ 3) + diastolic pressure.

or

((systolic - diastolic) / 3) + diastolic

Hypertension

130/80 mmHg beginning, 140/80 mmHg true

Acute hypertension

a short period of elevated blood pressure

Chronic hypertension

persistent high blood pressure, over 140/90 mm Hg

Korotkoff sounds

sounds heard while taking the blood pressure

The first sounds are systolic, last sounds are diastolic