The endocrine system Flashcards
1
Q
What is the endocrine system composed of
A
-endocrine glands that secrete hormones
-lacks continuity unlike the rest of the body organ system
2
Q
Who does the endocrine system work with?
A
-the nervous system and endocrine system both work together to control homeostasis
3
Q
What are the chemical messengers released by the endocrine system
A
hormones that are produced by cells, tissues , or organs
4
Q
Hormone
A
-means to excite, and regulate the physiological (metabolic) activity of cells
-circulating hormones release their effect in a target cell
-the onset of hormones effects and their length (half-life) differ between hormones
-the duration of a hormone varies from a fraction of a minute to a wee
5
Q
Endocrine system: response time, pathway type, and duration time
A
response time: slower
pathway type: extracellular fluid ex: blood
duration time: longer
6
Q
Nervous system: response time, pathway type, and duration time
A
response time: faster
pathway type: neurons
duration time: shorter
7
Q
List 5 the major effects of some hormones
A
- aids in reproduction, gametogenesis, fertilization, and implantation
- growth and development
- mobilizing body defense against pathogens
- maintaining water and electrolyte balance
- regulates cell metabolism and energy balance
8
Q
Endocrine glands
A
cells that secret hormones directly into the ECF (extracellular fluid) blood, lymph
9
Q
List the endocrine glands
A
- pineal gland
- pituitary gland
- thyroid gland
- parathyroid gland
- thymus
- adrenal gland
- ovaries
- testes
- pancreas (endocrine and exocrine)
10
Q
exocrine glands
A
use ducts to secrete non-hormonal substances onto a free surface, not endocrine in nature do not secrete hormones
11
Q
List the exocrine glands
A
- salivary glands
- sebaceous glands
- sweat glands
- mammary glands
- Brunner glands
- liver ( the largest gland in the body)
- pancreas
12
Q
List other structures that also contain endocrine tissue
A
- hypothalamus (neuroendocrine gland)
- atria of heart (upper chamber)
- kidney
- small intestine
- stomach
- placenta
- skin
- adipose tissue
13
Q
Target cell, tissue, organ
A
cell, tissue, or organ responding to the hormone
14
Q
paracrine signaling
A
-hormone only affects one or just a few different types of cells
-ex: somatostatin (inhibits the release of insulin) in pancreatic isle
- this is a localized effect
15
Q
endocrine signaling
A
-hormones affect many different types of body cells
- ex: insulin
- this is an overall effect
16
Q
chemistry of hormones
A
-the chemical nature of a hormone will determine its action on cells
17
Q
amino acid based hormones
A
-receptors usually on the outside of cells
-amino acids are water soluble
-embedded within the plasma membrane (made of fats)
18
Q
biogenic amines
A
a modification of the amino acid tyrosine
-based on 1 amino acid
- ex: thyroxine, epinephrine, norepinephrine
19
Q
peptides
A
short chains of amino acids
-ex: OT (oxytocin) and ADH (anti-diuretic hormone)
20
Q
proteins
A
long chains of amino acids
ex: insulin
21
Q
steroids
A
-synthesized from cholesterol, has receptors on the inside of the cell
-these are lipid-soluble hormones made by the adrenal gland, ovaries, and testes
22
Q
prostaglandins (PGs)
A
-biologically active lipids associated with nearly all cell membranes
-potent in very small amounts
- nicknamed local hormone (affect cyclic-AMP function)
-produce a variety of effects such as raising BP, pain, inflammation
23
Q
List the mechanisms of hormone action (at the cellular level)
A
- changes plasma membrane permeability, membrane potential, and opening/closing of ion channels
- synthesis of enzymes
- activates or deactivates enzymes
- increases secretory activity
- increase in mitosis
24
Q
Target specificity: hormones
A
-the ability of a target cell to respond to a hormone depends on the presence of specific receptors on the plasma membrane or within the cytoplasm to which the hormone can bond
25
What three things effect the hormone's effect on the target cell?
1. concentration of the hormone
2. number of receptors on or in the target cell
3. affinity between the hormone and the receptor
26
receptors
-they are not constant, they vary depending upon the type of cell
-are dynamic structures
27
up-regulation
- persistently low levels of hormones can cause its target to form additional receptors for that hormone
-can have greater potency even with the little amount there
28
down-regulation
-prolonged exposure to high hormone concentrations can decrease the number of receptors for that hormone
29
permissivness
-one hormone cannot exert its full effects without another hormone being present
ex: reproductive system hormones cause the development of the reproductive system, but you need thyroid hormone for the normal timely development, lack of will result in delay
30
synergism
-more than one hormone produces the same effects at the target cell and their combined effects are augmented
ex: glucagon and epinephrine both target the liver to release glucose. When together they release 150% more of what is released when they act alone
31
antagonism
-one hormone has the opposite effect of another hormone
ex: insulin and glucagon
-insulin lower blood glucose
-glucagon raises blood glucose
*made in pancreatic isle
32
secondary messenger systems
-used with water soluble amino acid based hormones cannot travel through to the plasma membrane of tissue cells and must exert their effects through intracellular second messengers, that are made when the hormone bind to or on the receptor
33
primary messenger
-the hormone therefor acts as this
34
5 steps in secondary messenger systems
1. the hormone binds to the receptor in the plasma membrane
2. the receptor activates the G-protein
3. The G-protein activates special enzymes such as adenylate cyclase
4. Adenylate cyclase converts ATP to cAMP
5.Cyclic AMP activates protein kinases that cause cellular changes
8cyclic AMP easily diffuses through the cell and acts as the second messenger
35
Direct gene activation system
-used with lipid soluble hormones
-lipid soluble hormones are chemically similar to plasma membrane and easily diffuse through target cell and bind to a receptor in cytoplasm or nucleus
-steroid hormones may activate genes within the nucleus of the target cell which cause synthesis of proteins that cause cellular changes
-this results in producing a structural or physiological effect
** steroid based hormones do not require a second messenger
36
Which amino acid based hormone does not stop outside the cell
thyroid hormone
-has iodine, and when it attaches to the plasma membrane it acts like a steroid based hormone and can penetrate the cell with the receptor located on the inside of the cell
37
stimuli
-result in endocrine glands manufacturing and releasing hormones
-the amount of hormones released depends on stimulus
38
How are most hormones controlled by?
-a negative feedback system
39
What are three ways a endocrine gland can be stimulated?
1. hormonal stimuli
2. humoral stimuli
3. neural stimuli
40
hormonal stimuli
- a hormone stimulates an endocrine gland to release its hormones
- ex: thyroid stimulating hormone
- ex: adrenocorticotropic hormone
41
Thyroid stimulating hormone (TSH)
-a hormone made by the pituitary gland that causes the thyroid gland to release thyroid hormone
42
Adrenocorticotropic hormone (ACTH)
-made by the pituitary gland that causes the release of hormones from the adrenal gland
43
humoral stimuli
-changes in the concentration of chemicals
- ions or nutrients in the bloodstream stimulate an endocrine gland to release its hormones
- ex: when blood levels of glucose are high, this causes the release of insulin to lower levels
- ex: when blood levels of calcium are high (depleting bone tissue) this causes the release of calcitonin to lower levels
44
neural stimuli
-nerve impulses stimulate an endocrine gland to release its hormones
- ex: sympathetic nervous system causes the adrenal glands to release norepinephrine and epinephrine
- ex: the hypothalamus (neuroendocrine gland) causes the posterior pituitary gland to secrete oxytocin
ex: the hypothalamus causes the posterior pituitary to secrete anti-diuretic hormone
45
Pituitary gland (hypophysis)
-called the master gland
-located within the Sella turcica of sphenoid done
-pea sized
-separated into anterior and posterior
-both lobes structurally and functionally separate
-posterior pituitary glands attached to the hypothalamus by a stalk like structure called the infundibulum
46
Anterior lobe (adenohypophysis)
-contains glandular epithelial cells
-true endocrine glands because made of epithelial tissue
-no direct neural connection with the hypothalamus
-releasing and inhibiting hormones secreted by neurons in the hypothalamus travel via the hypophyseal portal system where they regulate the anterior pituitary hormones
47
hypophyseal portal system
-the portal veins which connect the anterior pituitary to the hypothalamus
48
releasing hormones
stimulate the anterior pituitary to release hormones
49
inhibitory hormones
-inhibit the anterior pituitary from releasing hormones
50
Posterior lobe (neurohypophysis)
-composed of neuron cell bodies, axon bundles, and axon terminals that release oxytocin and anti-diuretic hormone
-the two hormones are produced in the hypothalamus
-the posterior pituitary is not a true endocrine gland
-neurohypophysis = infundibulum and posterior lobe o pituitary
-oxytocin and anti-diuretic hormone are transported down the axons of the hypothalamic-hypophyseal tract to the posterior pituitary
51
Hormones of the anterior lobe
-some anterior pituitary hormones are tropic hormones
-they regulate secretory action of other endocrine cells
- TSH, ACTH, FSH, and LH are trophic
-GH and Prolactin are no trophic hormones
-all anterior pituitary hormones affect target cells using cyclic AMP as their second messenger
-so this means all anterior pituitary hormones must be amino acid based and their receptors are located on the plasma membrane of target cells
52
Growth horomones
-also called somatotropin
-body cells increases mitosis especially bones
-bones have epiphyseal plate growth
-skeletal muscles increase muscle mass by enlargement of individual cells
-GH stimulates the liver to release insulin like growth factor (IGF), these act as hormones
- this is growth hormone acting as an indirect mediator
-GH transports fats from fat depots to cells which promote the use of lipids
-GH promotes glycogenolysis (glycogen broken into glucose) (diabetogenic effect)
-this is GH acting directly
-total amount of GH peaks during adolescence then declines with age
-GH is not a trophic hormone
53
Insulin-like growth factor (IGF)
-help cells pick up amino acids which allow for cell growth/division and the deposition of collagen fibers (ex: bone matrix)
54
Thyroid stimulating hormone (TSH)
-function is to stimulate the thyroid gland to secrete and release its hormones
55
Adrenocorticotropic hormone (ACTH)
-function is to stimulate the adrenal cortex to secrete and release hormones (especially the glucocorticoids) that help the body resist stress
=daily cycle-high in the morning, level affected by different factors such as fever, stress, and hypoglycemia
56
follicle stimulating hormone (FSH)
-is a gonadotropin, in females, it stimulates the gametogenesis of eggs and the release of estrogen
- in males, it simulates the gametogenesis of sperm in the testes
57
luteinizing hormone (LH)
-in females stimulates ovulation and release of hormones by the ovaries estrogen and progesterone
-in males stimulates the interstitial cells of the testes to produce testosterone
-FSH and LH are absent in pubescent boys and girls
58
Prolactin (PRL) lactogenic hormone
- in females stimulates milk production in mammary glands
-growing evidence shows it enhances testosterone in males
-high estrogen levels stimulate prolactin-releasing hormone
-in females, low estrogen levels stimulate prolactin inhibiting hormone
-high levels produced at the end of pregnancy, infant suckling stimulates the production of prolactin
59
oxytocin (OT)
-the synthetic name is Pitocin
-stimulates uterine contractions during labor
-stimulates vascular smooth muscle
-high levels found during childbirth and nursing women
-hormone triggers milk ejection "let down" reflex
-works on a positive feedback mechanism
-also plays a role in sexual arousal and orgasm
-plays role in affectionate behavior- cuddle hormone
-neurotransmitter in the brain
60
antidiuretic hormone (ADH)- vasopressin
-function is to inhibit/prevent urine production
-promotes water reabsorption from the kidneys (return water to the bloodstream)
-ADH release can be triggered by pain, low blood pressure, and certain drugs (morphine)
-alcohol inhibits ADH and causes increased urine output
- diuretics antagonize ADH, increases urine output, used to treat hypertension, edema
-severe blood loss can cause the release of ADH which causes vasoconstriction of visceral blood vessels, which will increase BP
61
oxytocin (OT)
-the synthetic name is Pitocin
-stimulates uterine contractions during labor
-stimulates vascular smooth muscle
-high levels found during childbirth and nursing women
-hormone triggers milk ejection "let down" reflex
-works on a positive feedback mechanism
-also plays a role in sexual arousal and orgasm
-plays role in affectionate behavior- cuddle hormone
-a neurotransmitter in the brain
62
Thyroid gland
-largest pure endocrine gland
-very vascular
-located below the larynx and anterior to the trachea
- has a bilobed gland
-composed of follicles which are fluid-filled sacs surrounded by cells
-makes two thyroid hormones thyroxine (T4) and triiodothyronine (T3) by the follicular cells
-T4 contains 4 iodine and T3 contains 3
-the parafollicular cells make calcitonin
-the colloid contains a premade version of thyroid hormone for the cells to use to make T3 and T4
63
bilobed gland
-two lateral lobes connected by an isthmus
64
What is the function of thyroxine and triiodothyronine
-major metabolic hormone (affects almost all organs except the adult brain, spleen, testes, uterus, and thyroid itself)
1. increases basal metabolic rate
2. increases body heat production
3. helps maintain BP
4. regulate tissue and growth
5. essential for normal skeletal and nervous system development
65
Regulation of thyroid hormone
1. hypothalamus: produces thyroid stimulating hormone releasing hormone to the anterior pituitary gland
2. Anterior pituitary gland: produces a thyroid-stimulating hormone and sends it to the thyroid gland
3. Thyroid gland: produces T4 and T3
66
negative feedback system
-a homeostatic control mechanism where the net effect is that the output of the system shuts off the original stimulus
67
calcitonin
hormone made by the parafollicular cells located between the follicles of the thyroid
-it lowers blood calcium levels by inhibiting osteoclast activity
68
parathyroid gland
- 4 glands embedded in the back of the thyroid gland
69
Principle (chief cells) produce what hormone?
parathyroid hormone (parathormone) PTH
70
What does parathyroid hormone do in the body?
-increases blood calcium levels by stimulating osteoclasts
-causes vitamin D to be converted into its active form calcitriol
71
What is calcium needed for in the body?
1. nerve impulse transmission
2. muscle contraction
3. osseous tissue matrix
4. blood clotting
** both PTH and CT are released due to humoral stimuli (blood calcium levels)
72
High blood calcium stimulates what?
-stimulates CT release
-so the blood calcium levels decrease
73
Low blood calcium stimulates what?
-PTH release so blood calcium levels increase
74
What are antagonistic hormones?
-a set of hormones that oppose the actions of one another
ex: PTH and calcitonin
75
Adrenal glands (suprarenal glands) location
superior to the kidneys
76
Adrenal glands (suprarenal gland) composition
-composed of 2 parts (unrelated structurally/functionally)
-adrenal cortex produces corticosteroids
-adrenal medulla produces catecholamines based on amino acid tyrosine
-produces 2 dozen steroids hormones
** the cortex is vital and the medulla is non-vital
77
zona glomerulosa
-produces mineralocorticoids (aldosterone) the most potent and abundant mineralocorticoid
78
Function of aldosterone
-targets kidney tubules to absorb Na+ and to excrete K+
-other ions follow Na+ and are reabsorbed
-water is reabsorbed by osmosis
- (INCREASE) in NA+ reabsorption = (INCREASE) H20 reabsorption = (INCREASE) in blood volume --> (INCREASE) in blood pressure
79
renin-angiotensin mechanism
(DECREASE) in blood pressure --> kidney secrets renin (this acts on angiotensionogen secreted by liver) + Angiotensionogen (plasma protein) --> angiotensin I + angiotensin converting enzyme (ACE) --> angiotensin II--> glomerulus cells secrete aldosterone--> (INCREASE) in blood volume --> INCREASE in blood pressure
80
Zona fasciculata produces what?
-produces glucocorticoids
-ex: cortisol
81
cortisol function
-the most abundant glucocorticoid
-ensures energy is provided for the body
-effects proteins and fat metabolism
-stimulates gluconeogenesis
-stimulates the release of fatty acids from adipose tissue
-provide resistance to stress
-decrease swelling
- decrease blood dilation
-slows wound healing
82
What is glucogenesis
-converting substances other than carbohydrates into glucose
-occurs in the liver
-changes fatty acids and amino acids into glucose
83
Stress effects and cortisol
-provides resistance
-Blood glucose (INCREASE) = energy during stress (INCREASE)
-Blood amino acids (INCREASE) = Available building blocks to build proteins necessary for dealing with stress (INCREASE)
84
Zona reticularis produces
-androgens and glucocorticoids
ex: androstenedione, dehydroepiandrosterone
85
Androgens
male sex hormones
86
chromaffin cells
-make the catecholamines
ex: norepinephrine (20% released) and epinephrine (80% released)
-both hormones exert the same effects with few exceptions
87
epinephrine
-exhibits a fight or flight effect
-mimics the effects of the sympathetic nervous system
1. increase heart rate
2. increase BP
3. increase breathing rate
4. Increase blood sugar levels (hyperglycemia)
5. relaxes bronchial musculature
88
Norepinephrine
-works at the post ganglion neurons of the autonomic nervous system
-exerts the same effect as epinephrine but it causes more peripheral vasoconstriction (INCREASE BP)
89
Pancreas location
-lays in a fold of mesentery behind the stomach, within the abdominal cavity
-regions include: head, body, tail
-is a mixed gland both endocrine and exocrine in nature
90
Acinar cells
-do not produce hormones
-instead they make enzyme containing juices carried to the small intestine via ducts
91
Pancreas (endocrine portion)
-pancreatic islets (Islets of Langerhans)
-over 1 million of these microscopic islands scattered over the pancreas
-composed of alpha and beta
92
Alpha cells
produce glucagon (hyperglycemic hormone) which raises blood glucose levels through...
1. increase glycogenolysis
( breakdown of glycogen into glucose in liver) --> liver release glucose and blood levels increase
2. Increase glucogenesis
(synthesis of new glucose in liver) --> liver release glucose and blood levels increase
93
glucagon and epinephrine are examples of what hormone interaction
synergism
94
beta cells
-produce insulin (hypoglycemic hormone), lowers blood glucose levels through
1. Increase glycogenesis (Join glucose back together to form glycogen)
2. Decrease glycogenolysis and gluconeogenesis
3.Increases glucose uptake by most body cells for ATP production
95
Insulin and glucagon are examples of what type of hormone interaction?
antagonism
96
Ovaries location
-near the lateral walls of the pelvic cavity
97
Functions of estrogen
-maturation of reproductive organs
-development of secondary sex characteristics (at puberty)
98
Functions of progesterone
-promotes growth and vascularity of inner lining of the uterus (facilitate implantation of fertilized egg and develop fetus)
-inhibits uterine contractions
99
Function of testosterone
- maturation of reproductive organs
-development of secondary sexual characteristics (at puberty)
-promotes maturation of sperm
100
Location of testes
-in scrotum
101
Which hormone has a permissive effect on reproductive system hormones ?
thyroid hormones
102
Pineal gland location
-at posterior aspect of diencephalon
103
Pineal gland secretory cells
pinacocytes
104
Calcium salt aggregates
-brain sand/ corpora arencea
-located between pinacocytes are landmarks for X-rays b/c they are radiopaque
105
Pineal gland produces what hormone
melatonin
106
Function of melatonin
-plays a role in our sleep and wake cycles
-melatonin levels rise and fall daily and may influence: Body temp, appetite, and sleep
1. high levels at night stimulate drowsiness
2. lower levels around noon: less tired
-in children may affect timing of puberty
107
Thymus gland location
-posterior to sternum in mediastinum
-large in childhood and continuously shrinks through adulthood
108
Thymus gland produces
1.Thymulin
2. Thymopoietin
3. Thymosin
- these hormones cause the undifferentiated stem cells in the thymus to develop into T lymphocytes (help immune response)
109
Heart: Atria
-upper chambers of the heart produce atria natriuretic peptide, which reduces blood sodium--> reduce blood volume--> reduce blood pressure
-this hormone is antagonistic to aldosterone
110
Gastrointestinal tract
-stomach produces ghrelin
-small intestine produces secretin and cholecystokinin (CCK)
-enteroendocrine cells (regulate a wide variety of GI functions)
111
Placenta
-a temporary endocrine structure preset only in pregnancy
-secretes estrogen, progesterone, and human chorionic gonadotropin
112
What does human chorionic gonadotropin do?
-stimulates ovaries (corpus luteum) to continue secreting progesterone during pregnancy
-helps maintain pregnancy
113
Kidneys make what hormone
-erythropoietin "red maker"
-this protein hormone stimulates the red bone marrow increase (hematopoiesis)
-man made erythropoietin is called epoetin
-patients on dialysis may be anemic and need to receive epoetin shots
114
Skin produces what ?
-cholecalciferol (D3) inactive vitamin D
-with the help of UV radiation skin cells convert Vitamin D2 molecules into D3
-D3 is activated through chemical reactions in the liver and kidney (convert to calcitriol)
-activated vitamin D (calcitriol) aids with calcium absorption in the small intestine
115
Adipose tissue release what?
-leptin following the uptake of glucose and lipids
-plays a role in appetite control and feelings of satiety
-decreases appetite
