Endocrine System Flashcards
8.1 INTRO TO ENDOCRINE SYSTEM 8.2 HORMONES THAT AFFECT BLOOD SUGAR 8.5 REPRODUCTIVE HORMONES
In 1889, scientists removed the pancreas from dogs and found that:
Rapid weight loss
Fatigued
Ants began gathering in the kennel
Endocrine System
Is an
Designed to
Stimulated by
Is an information signal system that uses blood vessels as information channels
Designed to maintain control over a long duration
Stimulated by the pituitary, secrete chemicals that affect the nerve activity of the hypothalamus
Nervous System
Is an
Designed to
Stimulated by
Is an information signal system that uses nerves to conduct information
Designed to adjust quickly to changes in the environment
Hypothalamus regulates the pituitary gland through nerve stimulation
The nervous system and endocrine system interact and work together to
provide control of organs and tissues
The Endocrine System Instrumental in regulating bodily process such as
Metabolism
Growth/development
Tissue function
Mood
The Endocrine System
An integrated system of
small organs that involve the release of signaling molecules known as HORMONES
Hormone
chemical regulators produced by cells in one part of the body that affect another part of the body
Only a small amount required to alter cell metabolism
2 Types of Hormones
Steroid/Lipid Hormones
Protein/Peptide Hormones
Steroid/Lipid Hormones
Made from cholesterol and includes male and female sex hormones and cortisol
They are not soluble in water but are soluble in fat
Cortisol - hormone that stimulates the conversion of amino acids to glucose by the liver
Eg. estrogen
Protein/Peptide Hormones
They contain chains of amino acids of varying length and are soluble in water
Eg. insulin and growth hormone
Steroid Hormones
Hormone diffuse from capillaries and into the target cells
Then, it combines w/ receptor molecules in the cytoplasm
This Hormone-receptor complex moves into nucleus, attaches to a segment of chromatin that has a complementary shape, activating a gene
So a message is sent to the ribosome in the cytoplasm to produce a specific protein
Protein Hormones
Protein hormones combine with receptors on the cell membrane
Activates production of an enzyme which causes the cell to convert ATP into cAMP
cAMP functions as a messenger, activating enzymes in the cytoplasm to carry out normal function
Pancreas
Pancreas contains 2 types of cells: Hormone-producing cells and Digestive-enzyme-producing cells
Adrenal Glands location and made up of
Location: above each kidney
Made up of 2 glands encased in one shell: adrenal medulla & adrenal cortex
Insulin
Location of hormone production
Effect
Islet of Langerhans (pancreas)
Increases permeability of cells to glucose; increase glucose uptake
Allows for the conversion of glucose to glycogen
Result: decrease in blood sugar
Glucagon
Location of hormone production
Effect
Islets of Langerhans (pancreas)
Promotes the conversion of glycogen to glucose
Result: increase in blood sugar
Cortisol
Location of hormone production
Effect
Adrenal cortex
Promotes the conversion of amino acids to glucose
Promotes the breakdown of fats to fatty acids
Decreases glucose uptake by the muscles (no by the brain)
Results: increase in blood sugar in response to stress
Testes
Produce sperm cells
Produce the hormone testosterone
Males sex hormone (testosterone) promotes
the development of facial and body hair
the growth of the larynx, lowering the voice
the strengthening of muscles
secretion of body oils (connected to development of acne)
Increase in oil production can create body odour
Hypothalamus and pituitary gland in the brain control the production of sperm and male sex hormones in the testes
Negative feedback systems
Hypothalamus secretes the GnRH
FSH acts on sperm-producing cells
FSH also causes sertoli cells to release a hormone called inhibin
Inhibin inhibits the production of FSH (by acting on anterior pituitary)
LH stimulates interstitial cells to produce testosterone
High levels of testosterone inhibits LH production (by deactivating hypothalamus)
Gonadotropin-releasing hormone (GnRH)
chemical messenger from the hypothalamus that stimulates the secretion of FSH and LH from the pituitary
Luteinizing Hormone (LH)
in male, hormone that regulates the production of testosterone
Follicle-Stimulating Hormone (FSH)
in male, hormone that increases sperm production
The Female Menstrual Cycle
Ovarian Cycle: an egg matures (from a primary oocyte) and is released
Uterine Cycle: the endometrium (lining) of the uterus builds up (becomes ready to have a fertilized egg
Ovarian Cycle:
an egg matures (from a primary oocyte) and is released
Uterine Cycle:
the endometrium (lining) of the uterus builds up (becomes ready to have a fertilized egg
The Role of FSH and LH: Pituitary Hormones
An oocyte (egg) & the cells around it are called the follicle Usually, only one follicle fully matures during each ovarian cycle. FSH matures the follicle
Ovulation -
The release of an egg (oocyte) from the follicle inside the ovary is triggered by a surge of LH
The Role Of Estrogen and Progesterone (Ovarian Hormones)
The corpus luteum is the remaining cells of the follicle after ovulation
The corpus luteum continues to produce estrogen and progesterone for approximately 2 weeks → maintains the thickness of the endometrium
Progesterone prepares the uterus for implantation of a fertilized egg
If no fertilization occurs, the egg degenerates → and the endometrium is no longer maintained and is shed from the uterus
Estrogen and Progesterone also control FSH and LH
Pituitary Hormones
LH and FSH control ovulation and the maturation of the follicle to release an egg
Ovarian Hormones
Estrogen and Progesterone
Control FSH and LH production
Sexual characteristics and prepare the uterine wall for egg implantation
GnRH released from hypothalamus
causes the release of LH and FSH from the pituitary gland
Follicular Phase
- FSH stimulate follicular development
- causes follicles to release estrogen
- estrogen initiates endometrium development
- ↑ estrogen produce (-) feedback to pituitary to reduce FSH
- ↑ estrogen produce (+) feedback to LH-producing cells of the pituitary gland
Ovulation Phase
- rising LH levels (LH surge) → oocyte burst out of follicle (ovulation)
Luteal Phase
- remaining cells (under influence of LH) transformed into corpus luteum
- release of estrogen and progesterone
- continue endometrium development
- (-) feedback to pituitary to reduce LH and FSH
- so ↓ in estrogen + progesterone → corpus luteum deteriorates
Flow Phase
- declining estrogen and progesterone signals uterine contractions … menstrual bleed
FLOW Phase Description of Events Hormone Produced Days
Menstruation
1 - 5
FOLLICULAR Phase Description of Events Hormone Produced Days
Follicles develop in ovaries
Endometrium is restored
Estrogen produced by follicle cells
6 - 13
OVULATION Phase Description of Events Hormone Produced Days
Oocyte bursts from ovary
14
LUTEAL Phase Description of Events Hormone Produced Days
Corpus luteum forms and endometrium thickens
Estrogen and progesterone
15 - 28
Follicle-stimulating hormone (FSH)
- in females, a gonadotropin that promotes the development of the follicles in the ovary
Luteinizing hormone (LH)
in females, a gonadotropin that promotes ovulation and the formation of the corpus luteum
