Exam 1 Flashcards
The nervous system and endocrine system work together… (2 things)
- to coordinate and direct the acitivity of cells
- to maintain homeostasis
Nervous System (what does it do? 3 things)
- reacts quickly 1-10 msec
- the effect is short
- uses electrical and chemical signals for communication
Endocrine System (what does it do?) 4 things
- reacts slowly (min-days)
- effect lasts longer
- uses hormones for communication
- control reproduction, growth, and development… more but idk if we need to remember this
What is homeostasis?
- Maintenance of a stable internal environment = dynamic state of equilibrium
What is homeostatic imbalance?
- a disturbance in homeostasis resulting in disease
Components of Homeostatic control (3)
- receptor
- control center
- effector
Endocrine glands are
ductless glands that release hormones (chemical messengers) in the interstital fluids or directly into the bloodstream
Major endocrine organs (6)
- pituitary
- thyroid
- parathyroid
- adrenal
-pancreas - gonads
The hypothalamus is a…
neuroendocrine organ (some neurons secrete hormones)
Endocrine vs. Exocrine (secretion)
Endo- product secreted into the interstitial area and eventually to the blood
Exo - product secreted into a duct
Hormones (2)
- chemical messengers that are released by endocrine cells – travel to target cells
- Target cells also have a specific receptor for the hormone (membrane or intracellular)
Receptors (3 general facts how they work)
2 examples of them
- specifically binds a hormone or group of hormones
- Binding with hormone activates the receptor
- As a result signal transduction occurs and a response is elicited
- GPCR and Tyrosine Kinase
Paracrine factors…
act locally affecting cell types other than those that release them
Autocrine factors…
act on the same type of cells that secrete them
Steroid (lipid-based) hormones (2 general facts)
- derived from cholesterol
- have intracellular receptors
Hydrophilic and lipophobic are what kind of hormones
Protein Hormones
Hydrophobic and Lipophilic are what kind of hormones
steroid hormones
Steroid Hormones (mechanism of action) hint: straight
go straight into the cell membrane (nucleus), causing transciption
Which hormones have a second messenger system?
protein hormones
Hypo is
decreased/low
Hyper
too high
*How are steroid hormones made?
- Cholesterol is transported into the mitochondria by the StAR protein (rate-limiting step)
- Side-chain cleavage enzyme, a mitochondrial enzyme, converts cholesterol to pregnenolone
What zone is Aldosterone made up in?
Zona glomerulosa Mineralocorticoids
What zone is Cortisol made up in?
Zona fasciculata Glucocorticoids
What zone is Testosterone made up in? (Adrenal)
zona reticularis Androgens
What zone is the makeup of testosterone to make Estradiol? (Ovaries)
Theca cell
What are the zones that makeup estradiol? (Ovaries)
Theca
granulosa cell
What hormone(s) are secreted by the gland? (Adrenal gland)
Aldosterone
Cortisol
Androstenedione
What hormones are secreted by the gland? (Ovaries)
Progesterone
Estradiol
What type of steroid hormones are made in the ovaries?
Sex hormones/reproductive hormones
How many compartments are involved in secretion of the hormones? (Ovaries)
2
Theca cells
granulosa cells
Progesterone needs how many compartments? What are they?
1 cell
Granulosa
Testosterone is what kind of hormone is made in the what (steroid)?
sex hormone made in the ovarian theca cell
Placenta is a what that synthesizes…
endocrine structure that synthesizes estrogen and progesterone
P/S: This hormone binds to tyrosine kinase receptor
protein/amino acid
P/S: The receptor for this hormone is found within the nucleus
Steroid
P/S: The signal from this hormone is amplified through a second messenger system
Protein/amino acid
P/S: This hormone’s activated receptors binds to a specific DNA sequence
steroid
P/S: This pituitary gland product is secreted as a pro-hormone before it is activated
protein/amino
P/S: This adrenal gland product is synthesized from cholesterol
steroid
P/S: This messenger activated a G-protein coupled receptor
protein/amino
P/S: Activation of this hormone’s receptor causes an increase in cellular calcium levels
Protein/amino
P/S: Adrenaline (epinephrine) uses the cAMP second messenger system
protein/amino
P/S: A glucocorticoid produced by the adrenal gland
steroid
The hypothalamus is connected to…(physcially)
the pituitary gland (hypophysis) by the infundibular stock (pituitary stock)
The hypothalamus controls 3 major systems to maintain homeostasis…
Autonomic nervous system
Neuroendocrine system
limbic system
The pituitary gland is responsible for
production of hormones that regulate the function of many endocrine glands in the body
Factors secreted in the hypothalamus travel to the anterior pituitary through… PORTAL SYSTEM
the blood
Which has a faster response? (protein/steroid hormones)
protein hormones
7 hormones produced from Anterior Pituitary (Protein)
ACTH
GH
MSH
TSH
FSH
LH
Prolactin
2 hormones produced from Posterior pituitary (Protein)
ADH (Vasopressin)
Oxytocin
GnRH
Gonadotropin releasing hormone
GHRH
growth hormone releasing hormone
SS
somatostatin (growth hormone inhibting hormone, GHIH)
TRH
thyroid releasing hormone
DA
dopamine (prolactin-inhibiting hormone)
CRH
corticotropin releasing hormone
What kind of connection between the hypothalamus and posterior pituitary? think TRACT
neural connection
Hypothalamo-hypophyseal tract
Synthesis and release of most hormones are controlled by a…
negative feedback mechanism
Negative feedbacks works in the…
opposite direction of the initial change (corrective adjustment)
Regulation of hypothalamic and anterior pituitary hormone secretion occurs via negative feedback (3 main steps)
- hypothalamus secretes a releasing/inhibiting factor
- cells in the anterior pituitary secrete another hormone in response to the hypothalamic factor
- hormone will then travel to a distant target gland
- the target gland secretes a hormone which travels to target cells
- when physiological change is sufficient to bring the body back to homeostasis, the hormone acts back at the hypothalamus and pituitary to suppress the activity of the axis
Positive feedback works as (2 things)
- result/response enhances the original stimulus
- the resulting change is in the same direction as the original stimulus
5 hypothalamic peptides
- TRH (thyrotropin-releasing hormone)
- GnRH (gonadotropin-releasing hormone)
- CRH (corticotropin-releasing hormone)
- GHRH (growth hormone-releasing hormone)
- GHIH (growth hormone-inhibiting hormone, Somatostatin)
Dopamine is a…
Secreted by…
a) neurotransmitter
b) secreted by neurons in the arcuate nucleus
In the absence of dopamine…
prolactin is continuously secreted by the lactotrope cells (lactotrophs) of the anterior pituitary
Where do protein hormones bind?
on the surface of the cell
What is the process called where the external signal (hormones) is transduced via internal intermediaries
signal transduction
GnRH releases…
FSH and LH
GHRH release and SS inhibts…
Growth hormone
TRH releases
TSH
DA inhibits
prolactin
CRH released
ACTH
Median eminence
function link btwn hypothalamus and anterior pituitary gland (blood circulation that will deliver to anterior pituitary
Infundibulum
physical connection between hypothalamus and pituitary
Anatomy of hypothalamus
composed of diff nuclei that regulate body function
Thyrotrope to ____ to ____
TRH to TSH
Gonadotroph to _____ to ______
GnRH to LH/FSH
Corticotrope to ____ to _____
CRH to ACTH
Somatotroph to ____ to ______
GHRH/GHIH to GH
Lactotroph to ____ to _____
PRH/PIH (Dopamine) to prolactin
4 tropic anterior pituitary hormones
TSH
ACTH
FSH
LH
Tropic effect
growth promoting
Tropic effect of TSH
maintains size and functional integrity of the thyroid glands
Tropic effect of ACTH
involved in growth of adrenal cells
Tropic effect of LH and FSH
LH: ovulation in females, production of testosterone by Leydig cells in males
FSH: development of egg cell, development of sperm cells
Prolactin regulates the…
synthesis of milk by the mammary glands
What are the two hormones synthesized by the magnocellular neurons of the hypothalamus?
vasopressin (ADH)
Oxytocin (OT)
ADH (vasopressin) is a regulator of
water balance
Oxytocin is released during…
Sex, orgasm, birth, breastfeeding
Oxytocin reduces
Stress and has calming effect
4 second messenger systems
- cAMP
- Protein kinase activity
- IP2/Ca2 DAG
- cGMP
cAMP second messenger system
- cAMP is generated from ATP through the action of the enzyme adenylate cyclase
- cAMP activates PKA
- when activated, PKA phosphorylates a number of other proteins EXAMPLE: glycogen is broken down to release glucose
Examples: glucagon, ADH, LH, FSH
Tyrosine Kinase Second Messenger System
- Phosphorylation of tyrosine residues on other proteins
- multiple signal transduction occurs
- ultimately activate transcription factors
Ex: insulin
IP3/Ca2 DAG second messenger system
- IP3 allows for release of calcium (second messenger) from the endoplasmic reticulum
- DAG (second messenger) activates protein kinase C which in turn phosphorylates proteins in the cell
ex: GnRH, TRH
cGMP mechanism
Activates PKG
Nitric oxide activates guanylate cyclase which converts GTP to cGMP
Stimulus suckling (oxytocin)
Stimulates contraction of myoepithelial cells in the mammary glands (milk let down)
Stretching/dilation of the cervix
Stimulates uterine contraction (labor)
Prolactin and Oxytocin (milk)
What does each have to do with milk?
Prolactin promotes milk synthesis
Oxytocin activates the milk letdown reflex
Circadian cycle
- 24 hr cycle
- changes are linked to light and dark
Biological clock does what
Produces the circadian rhythm and regulates their time
Pinealocytes are
Secretory cells that make up the pineal gland
Major product= melatonin
Melatonin affects on what in animals
Mating behavior and gonadal size
Melatonin may control production of
Antioxidant and detoxification molecules within cells
Receptors for Melatonin are what and what types ?
G-Protein Coupled (GPCRs)
M1 and M2
Suprachiasmatic Nucleus (SCN)
Central biological clock
Exposure to bright light can reset clock timing
SCN change melatonin lvls influence on (3)
Body temp
Sleep
Appetite
Sleep and jetlag acts on…
the SCN to entrain the central clock to external light/dark
In day animals, what happens with glucocorticoid levels and how does melatonin take effect?
- glucocorticoid levels are low after the onset of darkness and are high early in the morning
- due to inhibitory effects of melatonin
Melatonin Seasonal breeders (short/long, example)
Short-day breeder = sheep
long day breeder = quail
Melatonin levels are ___ during childhood.
Levels ____ at puberty
high
decrease
Patients with pre-eclampsia have…
lower nocturnal melatonin
Melatonin also believed to reduce
oxidative stress
Melatonin is a (think of systems)
pineal gland product
Vasopressin aka ___ is synthesized by neurons in the ____
- ADH, anti-diuretic hormone
- supraoptic nucleus (SON)
Describe G-protein couple receptors
- single polypeptide chain with 7 transmembrane domains
- receptor associated with a G-protein
- when ligand (hormone) binds, the Gsa becomes activated and associates with a membrane-bound enzyme
What types of hormones bind a nuclear receptor?
Steroid hormones
- testosterone progesterone
What kind of receptors do protein hormones have?
Membrane bound
Hormonal interaction: permissiveness
Situation when a hormone cannot exert its effects without the presence of another hormone
- repro hormones will not stimulate growth/development without thyroid hormone
Hormonal interaction: synergism
The combined effects of more than one hormone have a greater effect than the effect of any single one of the hormones
- glucagon and epinephrine both cause release of glucose from the liver
Hormonal interaction: Antagonism
One hormone opposes the action of another hormone
- insulin lowers blood glucose levels while glucagon increases
What is steroidogenesis?
Process of steroid hormone formation/synthesis
Which hormones are steroid hormones? (Sex hormones)
Estrogens - estradiol
Androgens - testosterone
Progesterone
Which hormones are steroid hormones? (Placenta)
Progesterone
Estrogens
What is the adenohypophysis?
Anterior pituitary
What is the neurohypophysis?
Posterior pituitary
Thyroid gland (3 characteristic)
- Bi-lobed in cats/dogs
- Highly vascular
- Affects different metabolic pathways
Parathyroid glands are located on the ______ aspect
Dorsal
Thyroid hormone is composed of 2 linked…
Thyrosine amino acids with iodine
Types of thyroid hormones secreted
Thyroxine (T4)
Tri-iodothyronine (T3)
Iodine essential for thyroid hormone synthesis
Synthesis of thyroid hormone (T4 and T3) occurs…
In the thyroid follicle
Hormonal Stimulus: GH effects (direct and indirect)
Direct: metabolic, anti-insulin, proteins
Indirect: growth promoting, IGF-1, skeletal/muscle systems, increase bone, cartilage, muscle
IGF1
Insulin-Like Growth factor 1
Hormonal Stimulus (Adrenal) steps
Anterior pituitary to Adrenal Cortex
ACTH to aldosterone and cortisol
Humoral Stimulus
Substances in the blood
1. Capillary blood contains low concentrations of Ca2+ which stimulates
2. …secretion of parathyroid hormone by parathyroid glands
Neural Stimulus
- Preganglionic sympathetic fibers stimulate adrenal medulla cells to
- Secrete catecholamines (epinephrine and norepinephrine)
An example of neural stimuli is the activation of the fight-or-flight response by the sympathetic nervous system. When an individual perceives danger, sympathetic neurons signal the adrenal glands to secrete norepinephrine and epinephrine.
ADH (vasopressin) has how many receptors and what do they control?
V1: smooth muscle -> muscle contractions
V2 using cAMP system: kidneys -> keep/reabsorb water
Both T4 and T3 bind….
Thyroid receptors
Who is more biologically active? (T4/T3)
T3
Thyroid Hormone (mech of action)
- Acts thru an intracellular receptor within the nucleus
- Initiates transcription and allows for synthesis of new proteins
- Alters cellular activity; increases ATP production and metabolic rate
Physiological importance of Thyroid Hormone
- Regulates basal metabolic rate (BMR)
- Promotes nervous/skeletal system development and maturity/function of the repro system
- Regulates the synthesis of degradation of other hormones and growth factors (permissive effect)
- Regulation of blood pressure
Thyroid hormone has a ____effect on many other hormones
Permissive
Hyperthyroidism
Too much thyroid
- increased metabolic rate
- weight loss and good appetite
- heat intolerance
- tachycardia
Graves’ disease
Autoimmune disease
Body makes antibodies against thyroid follicular cells that mimic TSH and continuously stimulate thyroid hormone release
Goiter
- dramatic enlargement of the thyroid gland
- Excess stimulation of TSH
iodine deficiency
What is the role of the hypothalamus?
Integration of body functions for the maintenance of homeostasis
Hypothalamus responsible for
Thermoregulation, neuroendocrine control, feeding/satiety and biological rhythms
Supraoptic (SON) from nucleus in the hypothalamus functions…
Fluid balance
Milk let-down
Parturition
What anterior pituitary cell populations are responsible for secreting each of the anterior pituitary products? (5)
Thyrotrope
Corticotroph
Lactotrope
Gonadotrope
Somatotrope
Steps to processing images with eye (4)
Retina
hypothalamus
superior cervical ganglion
pineal gland
Symptoms of Graves Disease
- goiter
- elevated metabolic rate
- weight loss
Symptoms of hypothyroidism
- decreased metabolic rate
- bradycardia (low heart rate)
- weight gain and lack of appetite
- cretinism (untreated hypothyroidism in the newborn)
- heat seeking, childlike face
