Endocrine Sytem Notes

8/10/2019 Endocrine Sytem Notes

1/45

NOTES: CH 11

The Endocrine System


2/45

HORMONES

HORMONE= a chemical signal secretedinto body fluids (usually blood);communicates regulatory messages within

the body.


3/45

TARGET CELLS= cells equipped torespond to specific hormones


4/45

HOMEOSTASIS

HOMEOSTASIS = maintaining the internalenvironment at a constant level (orbetween narrow limits), including:

-blood pH -oxygen / CO2levels -blood glucose -body temperature

-water balance

**achieved through

negative feedback!


5/45

**both the NERVOUS and ENDOCRINEsystems are involved in maintaining

HOMEOSTASIS!


6/45

ENDOCRINE SYSTEM

- ENDOCRINE GLANDS= hormone-secretingorgans

(ductless glands

they secrete hormones

directly into blood/fluid)


7/45

**there is much overlap with the nervoussystem

- NEUROSECRETORY CELLS: specializednerve cells that secrete hormones


8/45

How do Chemical Signals Work?

each chemical signal has a specific shape;

hormone binds to specific receptor ontarget cell

(cells are unresponsive if they lack theappropriate receptor);


9/45

How do Chemical Signals Work?

-binding of a chemical signal to a receptorprotein triggers chemical events within the

target cell:

1) Binds to receptor on plasma membrane,OR

2) Binds to receptor INSIDE the cell


10/45

Types of Hormones:

Hormones can be:

1) STEROIDS: synthesized

from cholesterol

OR

2) Proteins / peptides /

amines / glycoproteins:syn. from amino acids


11/45

STEROID HORMONES

Are insoluble in water / soluble in lipids

Action once it reaches the target cell:

1) Diffuses through cell membrane;

2) May combine w/a protein (receptor);

3) This hormone-receptor complex binds tospecific regions of target cells DNA;

4) Activates transcription of RNA of that

sequence;5) mRNA is transcribed and target cell

synthesizes proteins (e.g. enzymes,transport)


12/45


13/45

NONSTEROID HORMONES

e.g. proteins, peptides, amines, etc. typically combine w/

receptors in the target

cells PLASMA MEMBRANE

the receptor changes shape and asequence of molecular events (enzymesactivated via phosphorylation, etc.) thatresults in the target cell responding to thehormone.


14/45


15/45

NONSTEROID HORMONES

Examples of cellular responses to nonsteroidhormones:

-change in membrane permeability

-enzymes activated -promotion of syn. of specific proteins

-cell movement

-secretion of cell products (hormones, enz.) -stimulate/inhibit certain chemical pathways


16/45

LOCAL REGULATORS

LOCAL REGULATORS: affect nearby(local) cells

Growth Factors:

-peptides and proteinsthat function as local

regulators

-stimulate cells to grow,divide & develop normally


17/45

LOCAL REGULATORS

Prostaglandins (PGs):

-modified fatty acids-synthesized just before release (not stored)

-in semen, stimulate contraction of the smoothmuscles of the wall of the uterus; helps sperm

reach the egg-in placenta, stimulates uterus

muscles to contract in labor

-in immune system, help

to induce fever,

inflammation,

intensify pain


18/45

ENDOCRINE SYSTEM

*see fig. 11.1(p. 282): human

endocrine glands


19/45

HYPOTHALAMUS:

-region of lower brain-neurosecretory cells secrete hormones


20/45

PITUITARY GLAND:

-stores secretions from the hypothalamus

-located at base of hypothalamus


21/45

PITUITARY GLAND

POSTERIOR PITUITARY:under direct control of

neurosecretory cells

from the hypothalamus

ANTERIOR PITUITARY: responds to

RELEASING HORMONESfrom thehypothalamus (these travel through theportal veins and to the anterior pituitary)


22/45


23/45

Posterior Pituitary Hormones:

1) OXYTOCIN: induces contractions of

uterine muscles; triggers mammaryglands to eject milk

2) ANTIDIURETIC HORMONE (ADH):

causes water retention in the kidneys;decreases urine volume


24/45


25/45


26/45

Anterior Pituitary Hormones:

1) Growth hormone (GH)2) Prolactin (PRL)

TROPIC HORMONES(stimulate synthesis &release of hormones from OTHER endocrineglands)

3) Thyroid-stimulating hormone (TSH)

4) Adrenicorticotropic hormone (ACTH)

5) Follicle-stimulating hormone (FSH)

6) Luteinizing hormone (LH)


27/45

THYROID GLAND

Just below the larynx on either side and infront of the trachea

Thyroid hormones:

1) Thyroxine (T4)

2) Triiodothyronine (T3)

3) Calcitonin


28/45

Functions of Thyroid Hormones:

"THYROXINEand TRIIODOTHYRONINE:increase rate of energy release fromcarbs; increase rate of protein syn.;

accelerates growth

"CALCITONIN: lowers blood calcium and

phosphate ions


29/45


30/45

PARATHYROID GLANDS

on the posterior surface of thethyroid gland

PARATHYROID HORMONE(PTH): increases blood calciumconc. & decreases phosphate ionconc.

**in summary, calcitonin and PTHwork together to maintain stableblood calcium concentration


31/45

ADRENAL GLANDS

ADRENAL GLANDS: adjacent to

the kidneys; made up of 2 parts:

Adrenal cortex (outer

portion): -CORTISOL (glucocorticoid):

glucose metabolism

-ALDOSTERONE(mineralocorticoid):

salt & water balance


32/45

ADRENAL GLANDS

"ADRENAL MEDULLA (inner portion):

"Hormones include:

-epinephrine (adrenalin) -norepinephrine (noradrenalin)

-stimulates the fight or flightresponse to stress


33/45


34/45


35/45

Fight or Flight Response:

1) Glucose released from liver and muscles;2) Fatty-acid release from fat cells;

3) Increase rate and stroke vol. of heartbeat;

4) Bronchioles of lungs become dilated(increase rate of oxygen delivery to cells);

5) Blood diverted away from skin, digestive

organs and kidneys to the heart, brain &skeletal muscles (increase alertness andreadiness)


36/45


37/45

PANCREAS PANCREAS: contains endocrineand

exocrinecells (exocrine cells secretedigestive enz & bicarbonate into ducts)


38/45

PANCREAS

-the endocrine cells are called the ISLETSOF LANGERHANS

-alpha cells: secrete glucagon

-beta cells: secrete insulin


39/45

Feedback cycle to control blood glucose levels:

body cells &

liver cells takeup glucose

blood glucoselevel drops

Blood GlucoseLevel (90 mg/100 mL)

High glucose

level

Beta cellssecreteinsulin

Low glucose

level

blood glucose

level rises

liver cells breakdown glycogen

& release glucose

Alpha cellssecrete glucagon


40/45

Feedback cycle to control blood glucose levels:


41/45

PINEAL GLAND


42/45

PINEAL GLAND

located deep between the

cerebral hemispheres (brain)

secretes the hormone

MELATONIN in response to light conditions

-in the dark, nerve impulses from the retina tothe brain decrease, and melatonin secretionincreases

-works with the brain to regulateCIRCADIAN RHYTHMS

-may help regulate the female menstrual cycle,as well as the onset of puberty


43/45

GONADS

GONADS: (testes in males, ovaries infemales)


44/45

HORMONES PRODUCED BY THE GONADS:

1) Androgens: stimulate

development &maintenance of malereproductive system; (e.g.testosterone)

2) Estrogens: maintenance offemale reproductive

system; (e.g. estradiol)


45/45

HORMONES PRODUCED BY THE GONADS:

3) Progestins: preparing and maintaining uterus

to support growth and development of embryo;(e.g. progesterone)

**all 3 hormones are found in males andfemales, but in different proportions

Endocrine Sytem Notes

Documents