endocrine system

Endocrine System

Composition of the Endocrine System

Endocrine glands which are ductleses; These glands release hormones into the bloodstream.

Negative Feedback Loop

The process that opposes stimulus that moves body away from homeostasis in order to maintain homeostasis of the body.

Examples of Negative Feedback Loop

• when body temp increases, this system initiates sweating to return body back to balanced equlibrium state (homeostasis)

• when body temp decreases, this system initiates shivering to restore body back to homeostasis

Positive Feedback Loop

amplifies small stimulus.

reinforces change away from homeostasis, and allows events in the body to occur rapidly.

Examples of Positive Feedback Loop

• childbirth

• blood clotting

• nerve impulse conduction

Exocrine Glands

Glands that use ducts to secrete substances.

Examples include sweat glands, mammary glands, and salivary glands.

Target Cells

Hormones, chemicals produced by endocrine gland, travels throughout body via the bloodstream. Only cells with specific receptors, know as ___, can bind to these hormones.

The Three Components of the Endocrine System

receptor, control center, and effector.

sensory receptor, located in organs, signal control center when it detects organ is operating beyond normal limits (change in body’s homeostasis). the control center assimilates change by signalling effector to produce an appropriate response that will restore organ back to original state (restore body’s homeostasis)

Define the Two Main Categories of Hormones

1. Steroid Hormones: Lipid-soluble hormone that diffuses through cell membrane and binds to protein receptors in cytoplasm.

2. Protein Hormones: Water-soluble hormone that binds to receptors on the cell membrane.

Pituitary Gland

The “Master Gland” that works with the hypothalamus in coordinating the endocrine system and nervous system.

The posterior section stores hormones produced in the hypothalamus, which can be released when stimulated by nerve impulses from the hypothalamus.

The anterior section produces hormones, which can be released when stimulated by hormones released by hypothalamus.

Hypothalamus

Together with the pituitary gland, it coordinats the endocrine system and nervous system.

It signals the posterior pituitary gland through nerves that connect them.

It signals the release of anterior pituitary hormones by releasing hormones in the bloodstream which

Posterior Pituitary Hormones

- Oxytocin

- Antidiuretic Hormone (ADH)

Hormones Produced by the Anterior Pituitary Gland:

- Thyroid-Stimulating Hormone (TSH)

- Adrenocorticotrophic Hormone (ACTH)

- Human Growth Hormone (hGH)

- Follicle-Stimulating Hormone (FSH)

- Luteinizing Hormone (LH)

- Prolactin (PRL)

- Melanocyte-Stimulating Hormone (MSH) — DNTK

Antidiuretic Hormone

(ADH)

Produced in hypothalamus, stored in posterior pituitary gland.

Causes collecting ducts of kidney to become more permeable to water. Water exits collecting duct and moves back into blood. Increases water retention in blood and increases blood pressure.

Stimulus is dehydration from not drinking water, exercise, and alcohol consumption.

Oxytocin

Produced in hypothalamus, stored in posterior pituitary gland.

Known as the contraction hormone as it causes milk ducts and uterus to contract.

Stimulus is pressure on the cervix due to menstruation and child birth, and contraction of milk ducts for nursing mothers.

Human Growth Hormone

(hGH)

Produced in anterior pituitary gland.

Stimulates the growth of muscles and bones.

Stimulus is puberty and exercise.

Releasing Hormone

(Rh)

Produced in the hypothalamus.

Peptide that stimulates the posterior pituitary gland to release stored hormone ADH.

Stimulus is need for ADH.

Prolactin

(PRL)

Produced in anterior pituitary gland.

Causes mammary gland to increases milk production.

Stimulus is child birth and breastfeeding.

Insulin

Produced by beta cells in the islets of langerhans of the pancreas.

Decreases blood sugar levels by making all cells in body (muscles) to become permeable glucose and making liver convert glucose to glycogen.

Stimulus is high blood sugar which is when you are eating.

Glucagon

Produced by alpha cells in the islets of langerhans of the pancreas.

Increases blood sugar levels by making the liver convert glycogen to glucose, which will be released into the bloodstream by the liver.

Stimulus is low blood sugar which is when you are not eating and exercising.

Pancreas

Gland that is both an endocrine gland (ductless) and exocrine gland (uses duct).

Produces hormones and digestive enzymes.

Epinephrine and Norepinephrine

Produced in the adrenal medulla.

Increases blood sugar levels, heart rate, and blood pressure in the body. Prepares the body to be ready for short term stress.

Stimulus is the sympathetic nervous system.

Cortisol

Produced in the adrenal cortex.

Prepares the body for long-term stress by increasing blood sugar levels through breakdown of lipids and proteins.

Stimulus is ACTH (hormone produced by anterior pituitary gland)

Aldosterone

Produced in the adrenal cortex.

Prepares the body for long-term stress (hypertension) by increasing sodium and water reabsorption of the kidney.

Stimulus is ACTH (hormone produced by anterior pituitary gland)

Thyroxin

Produced in thyroid gland.

Increases metabolic rate in the body.

Stimulus is low body temp, exercising, and when wake up.

Calcitonin

Produced in thyroid gland.

Acts on bone and teeth cells to lower blood calcium levels by increasing deposition of calcium.

Stimulus is dairy consumption.

Parathyroid Hormone

(PTH)

Produced in parathyroid gland.

Increases blood calcium levels by inhibiting calcitonin. Calcium is removed from bones and teeth and is then reabsorbed by the kidneys. Stimulus is low blood calcium levels due to lack of dairy consumption, blood clotting, and exercise.

Testosterone

Produced by the leydig cells in the testes.

Assists in sperm production and gives men their secondary sexual characteristics (deep voice, facial hair, broad shoulderes).

Stimulus is LH, sex, exercise, aggresion, and puberty.

Estrogen

Produced in the follicles and corpus luteum of the ovaries.

Functions to increase endometrium lining, inhibit release of FSH, stimulate release of LH, and gives women their secondary sex characteristics (wider hips).

Stimulus is FSH during follicular phase and LH during luteal phase.

Progesterone

Produced by the corpus luteum of the ovaries.

Maintains the lining of the uterus, plays role in the development of follicle to an egg and fetal development, and help to maintain preganancy.

Follicle Stimulating Hormone

(FSH)

Produced in the anterior pituitary gland.

Hormone that causes follicle to develop in females, and sperm to develop in males.

Luteinizing Hormone

(LH)

Hormone that causes ovulation in females, and release of testosterone in males.

Adrenocorticotropic Hormone

(ACTH)

Produced in the anterior pituitary gland.

Hormone that causes the adrenal cortex to release its hormones.