The Endocrine System (OB1)

protein and amine hormones

Homeostasis

Maintaining a stable internal environment for cell function, endocrine system controls through chemical messengers

Endocrine System

Glands secreting hormones into the bloodstream.

Nervous System

exerts control by transmission of nerve impulses to and from the various tissues.

Endocrine Glands

secrete hormones into the extracellular fluid that surrounds the cells that make up the gland.

secretions passed into the capillaries transported in blood. ductless gland

Exocrine Glands

secrete substances into a duct that carries the secretion to the body surface or to one of the body cavities. e.g. sweat and mucuos glands

Hormones

Chemical messengers affecting cell functions, secreted by endocrine system

influence by: changing type/activties/ quantities of enzymes produced. not enzymes,

exert influencing by changing activity of enzymes or their conc by: activating genes in nucleus so proteins produced, changing shape/ structure of enzymes, changing rate of production increasing/ decreasing (transcription and translation)

Lipid Soluble Hormones

the ability to dissolve through the lipid (fat) portion of a membrane;

Water Soluble Hormones

Hormones unable to diffuse, act via receptors.

Saturation

All receptors occupied; no increased cell activity, the addition of hormones will not have a further effect. different cells have diff number and types of receptors, variation in sensitivities of cells to hormones

Steroid Hormones

Lipid-soluble, Slow to have effect but long-lasting effects

how to steroid hormones work

Once released into blood, bind to a transport protein enabling them to travel in blood.

then seperation from transport protein when at target cell

Diffuse across cell membrane and combine with a receptor protein inside the cytoplasm/nucleus.

Hormone-receptor complex binds to promoter region of gene to stimulate/inhibit transcription and therefore control protein synthesis for particular proteins.

Protein and amine Hormones

Water-soluble -Result in quick response by effects are short-lasting.

diagram of a pituitary gland

how do protein and amine hormones work

Attach to receptor proteins in the membrane of the target cell.
Combination of hormone and receptor results in a secondary messenger substance to diffuse through the cell and activate particular enzymes.

how hormones affect target cells/ organs

Hormones travel through the bloodstream to their target organs

target cell has specific receptor only bind to a specific hormone, which will only respond to that particular hormone, making the action specific.

hormones moving through the cell membrane diagram

Negative Feedback

maintains homeostasis.
a stimulus must trigger a change in the internal environment

Releasing Factors

Hormones stimulating secretion of hormones from the anterior pituitary.

Inhibiting Factors

Hormones reducing secretion of hormones from the anterior pituitary.

State where the hormones that are released from the anterior and posterior lobes of the pituitary are made

how is the hypothalamus connected to PPG

nuerosecretory cells in the infundibilum

how is the hypothalamus connected to APG

Hypopheseal portal system in the infundibulum

How do releasing and inhibiting factors work

The hypothalamus sends inhibiting and releasing factors via the hypophyseal portal system to the APG to secrete or stop secreting the hormone.

hypothalamus

serves as a connection between both the nervous and endocrine systems.

Regulates the main functions of the body, such as body temperature, water balance and heart rate, increasing and decreasing the secretions of the glands.

stimulates release of hormones from posterior and anterior

Posterior- Nervous control that causes the release. Occurs as they are connected by Neurosecretory cells

Anterior- released and stimulated by inhibiting and releasing factors

How are the hypothalamus and anterior and posterior glands connected

Anterior pituitary gland- connected to the hypothalamus via the blood vessels (hypophyseal portal system)

Posterior pituitary gland connected to hypothalamus by neurosecretory cells.

Thyroxine (T4) and Triiodothyronine (T3)

Production: Thyroid gland


Target: all cells


Effect: Controls/ Increases body metabolism by regulating catabolic reactions to release energy/ heat. Secreted in response TSH from APG

Calcitonin

Production: thyroid gland


Target: kidneys and bones


Effect: Decreases calcium and phosphate levels in blood by reducing reabsorption in the kidney, and decreasing breakdown of bone (bone releases calcium)

Parathyroid hormone (PTH)

Production: parathyroid gland


Target: Bones, kidneys + intestines


Effect: Increases calcium and phosphate levels in blood

Thymosin

Production: Thymus


Target: T- lymphocytes, Targets immune system


Effect: Influence maturation of T- lymphocytes.

Cortisol

Production: Adrenal cortex, (Adrenal glands)


Target: Most body cells


Effect: Promotes normal metabolism, helps body adapt to stress and repair damages tissues.

Aldosterone

Production: Adrenal cortex, (Adrenal glands)

Target: kidneys

Effect: Reduces NA+ and increase K+ in urine

Adrenaline (epinephrine)

Production: Adrenal medulla, (adrenal glands)

Target: Most cells/ tissues

Effect:Fight or flight responses (prepares body for threatening situation) e.g. increase heart rate, metabolic rate, blood pressure.

Noradrenaline (norepinephrine)

Production: Adrenal medulla, (adrenal glands)


Target: Most cells/ Tissues


Effect: Similar effect to adrenaline particularly increasing rate and force of heartbeat.

function of pancreas in terms of production of hormones

As well as hormones produced in cluster of cells called islets of Langerhans, the pancreas also produces enzymes (exocrine function)

Insulin

Production: pancreas

Target: Liver, muscles cells + fat storage, Produced by beta cells

Effect: Decrease blood sugar by:

Increasing glucose uptake by cells (particularly muscle), promoting glucose

Promotes glucose conversion to glycogen (fat), happens in liver and muscles.

Glucagon

Production: pancreas


Target: Liver, Produced by alpha cells

Effect: Increases blood sugar mainly by stimulating the breakdown of glycogen to glucose (liver), also breakdown of fats in liver and fat stores.

Androgens (testosterone)

Production: testes


Target: Many tissues


Effect: Stimulates sperm production

Growth of skeletal muscles
Development and maintenance of male sex characteristics

Oestrogen

Production: Ovaries


Target: Many tissues


Effect: Stimulates development of female characteristics, Regulates menstrual cycle

Progesterone

Production: Ovaries

Target: Uterus + mammary glands

Effect: Regulate menstrual cycle and pregnancy

Prepares mammary glands for milk secretion.

Follicle stimulating hormone (FSH) gonadadropin

Production: anterior pituitary gland

Target- ovaries and testes

Effect: Stimulates development/ growth of follicles

Stimulates production + maturation of sperm

Luteinizing hormone (LH)

Production: apg

Target: ovaries and testes

Effect: Triggers ovulation, formation of corpus luteum, Stimulates intestinal cells in testes to secrete male sex hormones (e.g. testosterone).

Adrenocorticotropic hormone (ACTH)

Production: APG

Target: adrenal cortex

Effect: Controls production + release of some hormones from the adrenal cortex.
(e.g. cortisol)

Growth hormone (GH)

Production: APG


Target: all cells


Effect:Stimulates body growth, particularly of Skeleton.
And protein synthesis. Maintains organ size, once mature.

Thyroid stimulating hormone (TSH)

Production: APG


Target: thyroid gland


Effect: Production + release of thyroid hormones (thyroxine)

Prolactin

Production: APG

Target: Mammary glands

Effect: Works with other hormones to initiate and maintain milk secretion in females.

Oxytocin

Production: PPG

Targets: uterus and mammary glands

Effect: Stimulates contraction of uterine muscles., Stimulates contraction of cells in mammary glands. Resulting in release of milk in breastfeeding.

Antidiuretic hormone

Production: PPG

Targets: Kidneys

Effects: Causes kidney to remove water from urine and return to blood (fluid retention), at high conc, also constricts small arteries.

Melatonin

Production: pineal gland


Target: most cells


Effect: regulates sleep cycle, circadian rhythm

Master gland

Pituitary gland- control the functioning of many other glands.

hyperthyroidism symptoms

symptoms of hypothyroidism

Goitre- enlargement of the thyroid gland, lump on neck.

Thyroid gland- due to thyroid gland working extremely hard to produce thyroid hormone.

Unexplained weight gain,

Fatigue

Emotional mood changes

Constipation

Swollen ankles,

Joint pain

causes of hypothyroidism

insufficient amount of thyroid hormone (thyroxine) being produced

treatments of hypothyroidism

pituitary surgery, increase iodine, thyroxine tablets.

what causes hyperthyroidism

treatments of hyperthyroidism