Endocrine System Flashcards
(100 cards)
1
Q
Endocrine cells release
secretions into ———–
A
extracellular fluid
2
Q
Endocrine cells and
tissues produce about ——– , and it ——- and
——– body processes
A
- 30 different hormones
(chemical messengers) - Controls and
coordinates
3
Q
Mechanisms of intercellular
communication……
A
- Direct communication
- Paracrine communication
- Autocrine communication
- Endocrine communication
- Synaptic communication
4
Q
- Exchange of ions and
molecules between
adjacent cells across
gap junctions
– Occurs between two
cells of the same type
– Highly specialized and
relatively rare
A
Direct communication
5
Q
Chemical signals
transfer information
from cell to cell within a
single tissue
A
Paracrine communication
6
Q
Messages affect the same cells that secrete them
A
Autocrine communication
7
Q
examples of Autocrine hormones
A
E.g., prostaglandins secreted by smooth muscle
cells cause the same cells to contract
8
Q
- Endocrine cells release chemicals (hormones) that
are transported in bloodstream - Alters metabolic activities of many organs
A
Endocrine communication
9
Q
- Neurons release neurotransmitters at a synapse
- Leads to action potentials that are propagated along
axons - Allows for high-speed “messages” to reach specific
destinations - Ideal for crisis management
A
Synaptic communication
10
Q
Function of Hormones
A
- Change types, quantities, or activities of enzymes and
structural proteins in target cells - Can alter metabolic activities of multiple tissues and
organs at the same time - Affect long-term processes like growth and
development
11
Q
Classes of hormones
A
Amino acid derivatives
Peptide hormones
Lipid derivatives
12
Q
Not lipid soluble
Unable to penetrate plasma membrane
Bind to receptor proteins on outer surface of plasma
membrane (extracellular receptors)
A
Catecholamines and peptide hormones
13
Q
Lipid soluble
Diffuse across plasma membrane and bind to
receptors inside cell (intracellular receptors)
A
Steroid and thyroid hormones
14
Q
What are The Classes of hormones
A
1-Amino acid derivatives
2- Peptide hormone
3- Lipid derivatives
15
Q
Derivatives of tyrosine
A
- Thyroid hormones
- Catecholamines
(epinephrine,
norepinephrine, and
dopamine)
16
Q
Derivatives of tryptophan
A
Serotonin and melatonin
17
Q
Most are synthesized as pro-hormones, Inactive molecules converted to active hormones before or after they are secreted
A
Peptide hormones
18
Q
Proteins more than 200 amino acids
long that have carbohydrate side
chains (e.g., TSH, LH, FSH)
A
Glycoproteins
19
Q
Insulin, GF, ADH, OXT, PLC
A
Short polypeptides/small proteins
20
Q
——- derived from arachidonic acid, a 20-
carbon fatty acid
A
Eicosanoids
21
Q
——- coordinate local cellular activities
Converted to thromboxanes and ——– in some tissues
A
Prostaglandins
prostacyclins
22
Q
—— derived from cholesterol
Include:
A
Steroid hormones
- Androgens from testes in males
- Estrogens and progesterone from varies in females
- Corticosteroids from adrenal cortex
- Calcitriol from kidneys
23
Q
They are bounded to specific transport proteins in the plasma and remain in circulation longer than peptide hormones
A
Steroid hormones
24
Q
Free hormones remain functional for less than an hour and
are inactivated when they;
A
- Diffuse out of bloodstream and bind to receptors on
target cells,
– Are absorbed and broken down by liver or kidneys,
– Are broken down by enzymes in blood or interstitial fluids
25
Binding of a hormone to its receptors may;
* Alter genetic activity
* Alter rate of protein synthesis
* Change membrane permeability
26
-------- is an Enzyme complex coupled to
membrane receptor and Involved in link between first messenger and second messenger
G protein
27
Intermediary molecule that appears due to
hormone–receptor interaction
May act as enzyme activator, inhibitor, or cofactor Results in change in rates of metabolic reactions
* E.g., cAMP, cGMP, Ca2+
Second messenger
28
Steps involved in increasing cAMP level, which
accelerates metabolic activity of cell
1- Hormone binds to receptor
2- G Protein activation due to the receptor-hormone interaction
3- Activated G protein activates adenylate cyclase
4- Adenylate cyclase converts ATP to cyclic AMP
5- Cyclic AMP functions as a second messenger
6- Generally, cyclic AMP activates kinases that
phosphorylate proteins which will either increase enzyme synthesis or open ion channels
7- Leads to Increase in cAMP level but is usually short-lived so Phosphodiesterase (PDE) converts cAMP to AMP
29
steps involving G proteins and calcium ions
1- Hormone binds to receptor
2- G Protein activation due to the receptor-hormone interaction
3- Activated G protein activates phospholipase C (PLC)
4- Triggers receptor cascade beginning with production of diacylglycerol (DAG) and inositol triphosphate (IP3) from phospholipids
5- IP3 diffuses into cytoplasm and triggers release of Ca2+ from intracellular reserves
6- Calcium ion channels open due to activation of protein kinase C (PKC), and Ca2+ enters cell
7- Ca2+ binds to calmodulin, activating enzymes
30
Function of The hypothalamus
1- Regulates functions of the
pituitary gland
2- Synthesizes ADH and OXT
and transports them to
posterior pituitary gland for
release
3- Secretes regulatory
hormones that control
secretory activity of anterior
pituitary gland
4- Contains autonomic centers
that exert direct control over
adrenal medulla
31
The size of the pituitary gland is about
------- of an inch in diameter and located at
the base of the------ near the
--------------. They are connected by
the pituitary stalk, the --------------------.
1/3 , brain ,hypothalamus, infundibulum
32
Hypothalamic control of anterior lobe
– Releasing hormones (RH)
Stimulate synthesis and secretion
of one or more hormones at
anterior lobe
– Inhibiting hormones (IH)
Prevent synthesis and secretion of
hormones from anterior lobe
33
Anterior lobe of pituitary gland
– Also called ------------------.
adenohypophysis
34
The Anterior lobe has three regions;
- Pars distalis - secret other pituitary hormones
– Pars tuberalis
– Pars intermedia - secret MSH
35
Hormones of anterior lobe;
- TSH
- FSH
- LH
- GH
- PLC
- ACTH
- Gonadotropins
36
Production of FSH and LH is stimulated by
-------------.
gonadotropin-releasing hormone (GnRH)
37
----------- Caused by low production of gonadotropins
Hypogonadism
38
Growth hormone stimulates.....
Liver cells to release somatomedins that stimulate
tissue growth
39
Somatomedins causes....
- Somatomedins cause skeletal muscle fibers and
other cells to increase uptake of amino acids
- Stem cells in epithelia and connective tissues to divide
- Breakdown of triglycerides in adipocytes, which leads to glucose-sparing effect
- Breakdown of glycogen by liver cells causing
diabetogenic effect
40
Posterior lobe of the pituitary gland
* Also called ...........
neurohypophysis
41
.......... Contains unmyelinated axons of hypothalamic
neurons
Posterior lobe of the pituitary gland
42
........... synthesis Antidiuretic hormone
(ADH)
Supra-optic
43
---------------- synthesis Oxytocin (OXT)
Paraventricular nuclei
44
- Stimulates contraction of uterus during labor
- Promotes ejection of milk after delivery
OXT
45
The thyroid gland consists of two lobes connected by ...........
narrow isthmus
46
The location of the thyroid gland
Lies inferior to thyroid cartilage of larynx
47
....................., are hollow spheres lined by cuboidal epithelium and surrounded by capillaries
- Thyroid follicles
48
Epithelial cells of the thyroid follicles absorb ...... from
blood
iodide ions (I–)
49
............... contains viscous colloid (sticky
secretions)
Follicle cavity
50
..................... produce
calcitonin (CT)
C (clear) cells, or parafollicular cells
51
The synthesis, storage, and secretion of thyroid hormones;
1- Iodide ions are absorbed from the digestive tract and delivered to the thyroid gland by the bloodstream.
2- Endocytosis Iodide ions diffuse to the apical surface of each follicle cellvwhere they are converted into an atom of iodine (I0). Thevtyrosine portion of thyroglobulin bind the iodine atoms.
3- Iodine-containing thyroxine molecules become linked to form thyroid hormones (T3 and T4)
4- Follicle cells remove thyroglobulin from the follicles by endocytosis.
5- Lysosomal enzymes break down the thyroglobulin, and the amino acids and thyroid hormones enter the cytoplasm.
6- The released T3 and T4 diffuse from the follicle cell into the bloodstream.
7- A majority of the T3 and T4 bind to transport proteins.
52
............., Globular protein synthesized by follicle cells
Thyroglobulin
- Secreted into colloid of thyroid follicles
- Contains the amino acid tyrosine;the building block of thyroid hormones
53
..............., Proteins that bind about 75 percent of T4 and 70 percent of T3 entering the bloodstream
Thyroid-binding globulins (TBGs)
54
The Function of the Thyroid hormones - T4
- Affect almost every cell in body
- At the target cell, when binds to cytoplasmic receptors, they are stored and their release is regulated by –ve feedback mechanism
- When binds to surfaces of mitochondria increase
ATP production Increased metabolic rate , energy
consumption and heat generation of cells.
55
............. Responsible for strong, immediate, and shortlived increase in rate of cellular metabolism
Thyroid hormone - T4 tetraiodothyronine
56
............... In children, essential to normal development of skeletal, muscular, and nervous systems
Thyroid hormone - T4 tetraiodothyronine
57
Function of the Thyroid hormones - Calcitonin (CT)
- Helps regulate concentrations of Ca2+ in body fluids - Stimulates Ca2+ excretion by kidneys
- Prevents Ca2+ absorption by digestive tract
58
Two pairs of .............
embedded in the posterior surface of
the thyroid gland
Parathyroid Glands
59
............... produce Parathyroid Hormone (PTH) in
response to low concentrations of Ca2+
- Antagonist for calcitonin
Parathyroid (chief) cells
60
Physiological function of PTH
- Accelerates mineral turnover and releases
Ca2+ from bone
- Reduces rate of calcium deposition in bone
- it enhances reabsorption of Ca2+ at kidneys,
reducing urinary losses
- It stimulates formation and secretion of calcitriol
by the kidneys
- Also enhances Ca2+, PO4 absorption by the digestive tract
61
Location of Adrenal Glands
Lie along superior border of each kidney
62
............. Stores lipids, especially cholesterol
and fatty acids
Adrenal cortex
63
.......... produces steroid hormones
(corticosteroids)
Adrenal cortex
64
.............. Secretory activities controlled by
sympathetic division of ANS and produces epinephrine (adrenaline) and norepinephrine
Adrenal medulla
65
Adrenal cortex is Subdivided into three regions :
1. Zona glomerulosa
Produces mineralocorticoids, i.e aldosterone
2. Zona fasciculate
Produces glucocorticoids, i.e. cortisol
(hydrocortisone) with corticosterone
3. Zona reticularis
Produces androgens under stimulation by ACTH
66
.............. Stimulates conservation of sodium ions and
elimination of potassium ions
Aldosterone
67
............. Increases sensitivity of salt receptors in taste buds
Aldosterone
68
Aldosterone, Secretion responds to:
1- Drop in blood Na+, blood volume, or blood
pressure
2- Rise in blood K+ concentration
69
.............. Accelerate glucose synthesis and
glycogen formation
Glucocorticoids
70
................ Show anti-inflammatory effects
and Inhibit activities of white blood cells
and other components of immune system
Glucocorticoids
71
Adrenal Medulla
- Contains two types of secretory cells:
- One produces epinephrine (adrenaline), 75% to 80% of medullary secretions
- The other produces norepinephrine
(noradrenaline), 20% to 25% of medullary secretions
72
Activation of the adrenal medulla has the following
effects:
1- In skeletal muscles, epinephrine and norepinephrine trigger mobilization of glycogen reserves and accelerate the breakdown of glucose to provide ATP
- This combination increases both muscular strength and endurance
2- In adipose tissue, stored fats are broken down into
fatty acids
- Which are released into the bloodstream for other
tissues to use for ATP production
3- In the liver, glycogen molecules are broken down
- The resulting glucose molecules are released into
the bloodstream
- Primarily for use by neural tissue, which cannot
shift to fatty acid metabolism
4- In the heart, the stimulation of beta 1 receptors
triggers an increase in the rate and force of cardiac muscle contraction
73
Location of Pineal Gland
Lies in posterior portion of roof of
third ventricle
74
The Pineal Gland contains ..........,
which synthesize hormone ...........
- Pinealocytes
- melatonin
75
Functions of Melatonin:
- Inhibits reproductive functions
- Protects against damage by free radicals
- Influences circadian rhythms
76
Location of Pancreas
Lies between inferior border of stomach
and proximal portion of small intestine
77
................. Contains exocrine and endocrine cells
Pancreas
78
............... Consists of cells that form clusters known as
pancreatic islets, or islets of Langerhans
Endocrine Pancreas
79
pancreatic islets:
1. Alpha cells produce ......
2. Beta cells produce .......
3. Delta cells produce ......
4. F cells secrete...............
1. glucagon
2. insulin
3. peptide hormone identical to GH–IH
4. pancreatic polypeptide (PP)
80
When Blood Glucose Levels rise:
Beta cells secrete insulin, stimulating transport of
glucose across plasma membranes
81
When Blood Glucose levels decline:
Alpha cells release glucagon, stimulating glucose
release by liver
82
......... Is a peptide hormone released by beta cells
Insulin
83
Insulin function
1- Accelerates glucose uptake
2- Accelerates glucose utilization and enhances ATP
production
3- Stimulates glycogen formation
4- Stimulates amino acid absorption and protein
synthesis
5- Stimulates triglyceride formation in adipose tissue
84
............. Released by alpha cells
Glucagon
85
Glucagon function
1- Mobilizes energy reserves
2- Affects target cells
3- Stimulates breakdown of glycogen in skeletal muscle and liver cells
4- Stimulates breakdown of triglycerides in adipose
tissue
5- Stimulates production of glucose in liver
(gluconeogenesis)
86
Hormones Produced by the Pancreatic Islets
- Glucagon, from Alpha cells
- Insulin, from Beta cells
- GH-IH, from Delta cells
- PP, from F cells
87
................. Is characterized by high glucose concentrations high enough to overwhelm the reabsorption capabilities of the kidneys
Diabetes Mellitus
88
............. abnormally high glucose levels
in the blood in general
Hyperglycemia
89
........ appears in the urine, and urine volume
generally becomes excessive (........)
Glucose , (polyuria)
90
............... Is characterized by inadequate insulin production by the pancreatic beta cells
Type 1 (insulin dependent) diabetes
91
............ Is the most common form of diabetes mellitus
Type 2 (non-insulin dependent) diabetes
92
................ Most people with this form of diabetes produce normal amounts of insulin, at least initially, but their tissues do not respond properly, a condition known as ..............
Type 2 (non-insulin dependent) diabetes
insulin resistance
93
Type 2 diabetes is associated with .......
obesity
94
Complications of untreated, or poorly managed
diabetes mellitus include:
1. Kidney degeneration
2. Retinal damage
3. Early heart attacks
4. Peripheral nerve problems
5. Peripheral nerve damage
95
Diabetic retinopathy
(Diabetes Mellitus) - Retinal Damage.
The proliferation of capillaries and
hemorrhaging at the retina may cause
partial or complete blindness
96
Diabetic nephropathy
(Diabetes Mellitus) - Kidney Degeneration.
Degenerative changes in the kidneys, can lead to kidney failure
97
Degenerative blockages in cardiac circulation can lead to ..........
early heart attacks
98
Diabetic neuropathy- Peripheral Nerve Problems
Abnormal blood flow to neural tissues is probably responsible for a variety of neural problems with peripheral nerves, including abnormal autonomic function
99
Diabetic neuropathy - Peripheral Nerve Damage
Blood flow to the distal portions of the limbs is reduced, and peripheral tissues may suffer as a result
100
A reduction in blood flow to the feet can
lead to tissue death, ulceration, infection, and loss of
toes or a major portion of one or both feet
this is an example of ...........
Peripheral Nerve Damage
