Exam 4 Flashcards
Compare and contrast nervous and endocrine system control
Nervous system - #1 controlling system of the body
- Neurons: release NTs
- Very fast, quick response by effectors
- Short-lived effect
Endocrine system - #2 controlling system of the body
- Glandular cells: hormones
- Lag time before response by target cells
* Hormone must travel through
bloodstream in order to reach
target cell
- Longer-lasting effect
- Both systems function in communication with other parts of the body
Contrast endocrine and exocrine
Endo = within
-crine = to secrete
Endocrine glands: hormones sent to target tissue through bloodstream
Exocrine lands: secretions sent through a duct to membrane surface
Give examples of endocrine glands
- Pineal gland
- Hypothalamus
- Pituitary gland
- Thyroid
- Parathyroid glands
- Thymus
- Adrenal
- Pancreas
- Ovary
- Testis
Contrast the 2 classes of hormones based on their structure
Amino acid based
- Composed of amino acids/derivatives
of amino acids
Steroid bases
- Made form cholesterol
- Examples: sex hormones and adrenal
cortex hormones (cortisol)
Define target cells
Cells with a receptor for a specific hormone that can respond to that hormone; the target of a hormone’s effect
Define receptor
(1) a peripheral nerve ending specialized for response to particular types of stimuli; (2) molecule that binds specifically with other molecules, e.g., hormones and neurotransmitters
Contrast the function of water-soluble and lipid-soluble hormones
Lipid-soluble/steroid hormones: can use direct gene activation or indirect
^ diffuse through the plasma membrane
to enter the target cell and bind to a
receptor protein.
Water-soluble/amino acid hormones: Indirect pathway
^ bind to a receptor protein on the plasma
membrane of the cell.
Contrast hormone mechanisms of action via direct gene activation and second messenger signaling
Direct gene activation
^ Steroid hormone (outside the cell)
^ Moves past plasma membrane and into cell through cytoplasm
^ Moves into nucleus
^ Binds receptor protein
^ Hormone-receptor complex interacts with DNA
^ Gene is turned on > mRNA transcribed > protein
Second messenger signaling
^ Hormone behaves as first messenger
(outside cell)
^ Binds membrane receptor, setting off a
chain reaction of events
^ After binding of receptor, enzyme
becomes active
^ Active enzyme then activates second
messenger (ex: cAMP)
^ Second messenger then has an effect on
cellular function, such as glycogen
breakdown
What are the three ways that the body controls the release of hormones
- Hormonal stimulus
- Humoral stimulus
- Neural stimulus
Describe the hormonal stimulus
- A gland secretes a hormone that then goes on to stimulate another gland to stimulate another hormone and so on – typically a 3-step pathway
^ Controlled by negative feedback
^ Ex: The hypothalamus secretes
hormones that stimulate the anterior
pituitary gland to secrete hormones that
stimulate other endocrine glands to
secrete hormones
Describe the neural stimulus
- Neural stimulus
^ Preganglionic sympathetic fiber
stimulates adrenal medulla cells to secrete
catecholamines (epinephrine and
norepinephrine)
Describe the humoral stimulus
- Humoral = blood
^ Capillary blood contains low
concentration of Ca2+, which stimulates
secretion of parathyroid hormone (PTH)
by parathyroid glands
What are the major anterior pituitary hormones/their functions and targets?
Hypothalamus also makes releasing hormones, such as GHRH and TRH, which then tell the anterior pituitary to release hormones such as…
- GH (growth hormone)
- TSH (thyroid stimulating hormone)
- ACTH (stimulates the adrenal cortex)
- FSH and LH (reproductive hormones,
stimulate the gonads = gonadotropins)
- PRL (prolactin)
What are the major hormones stored and released by the posterior pituitary and what are their functions?
- Oxytocin: causes uterine contraction during labor and targets mammary glands (milk let-down reflex)
- ADH: anti-diuretic hormone, targets kidney tubules, balances water in body
Describe the relationship between the hypothalamus and posterior pituitary as well as the hypothalamus and anterior pituitary
Hypothalamus and the posterior pituitary:
^ Hypothalamus is responsible for the
synthesis of oxytocin and ADH
^ Oxytocin and ADH are then
transported and released to the
posterior pituitary gland, where they are
stored until they are needed
^ The posterior pituitary does not
make any hormones on its own – it
simply stores and releases ADH and
oxytocin as needed and releases them
into bloodstream
Hypothalamus and anterior pituitary:
^ The anterior pituitary is under the
control of the hypothalamus
^ Hypothalamus also makes releasing
hormones, such as GHRH and TRH,
which then tell the anterior pituitary to
release hormones
_____ and _____ are the only non-endocrine targets of the anterior pituitary hormones
GH, PRL
Describe gigantism
Hypersecretion of GH in children (growth plates still open)
What is the function of GH?
- General metabolic hormone
^ Target cells increase in size and divide
^ Long bone growth
^ Increase in muscle mass - Effects on metabolism
^ Gat breakdown
^ Glucose sparing
^ Helps glucose stay in homeostasis
Describe acromegaly
Hypersecretion of GH in adults (growth plates closed)
^ Thickening of the bones, especially in
the face, hands and feet
Describe pituitary dwarfism
Hyposecretion of GH in children
^ Proportional limb sizes
What pathologies are associated with too much or too little GH?
Gigantism, acromegaly, pituitary dwarfism
What is/are the function(s) of thyroid hormone?
- Thyroid hormones inhibit anterior pituitary and hypothalamus
^ Negative feedback control - TH effects
^ Increases BMR
^ Increased glucose “burn” rate
^ Glucose energy to ATP
^ Responsible for heat production
^ Regulates tissue growth and
development (particularly important in
infants and children)
What is the location of the thyroid hormone?
Situated in the anterior part of the neck
^ Butterfly-shaped gland situated across the trachea
What are the major hormones of the thyroid gland?
Major hormones
- Thyroxine (T4)
^ Major hormone
^ 4 atoms of iodine
- Triiodothyroxine (T3)
^ Formed at target tissues
^ 3 atoms of iodine
- Calcitonin
^ Calcium deposit > bones
What is myxedema? What is it characterized by/what are the symptoms?
- Hypothyroidism in adults
- Unexplained weight gain, sluggish mentally and physically, low BMR, fatigued, cold
Describe the control of PTH
- Any time there is a blood-calcium imbalance/reduced amount of calcium ions, PTH steps in to correct this
^ PTH is stimulated by reduced calcium
ions
^ Signals sent to osteoclasts
^ Osteoclasts degrade bone matrix,
releasing calcium ions
^ Calcitonin = antagonist, works in
opposite way
^ Too much calcium ions > deposits
calcium in bones
High potassium levels would cause the release of…
aldosterone
What is cretinism? What is it characterized by/what are the symptoms?
- Hypothyroidism in infants
- Dwarfism, mental retardation, other developmental problems
- TH is screened in infants
What is goiter? What is it characterized by/what are the symptoms?
- Enlarged thyroid gland
- Often caused by iodine deficiency
- The body can’t make thyroid hormone, but the hypothalamus and anterior pituitary don’t know this, so they continue to signal for TH to be made and overstimulate the thyroid gland which then becomes enlarged
What is Grave’s disease?
- The most common kind of hyperthyroidism in adults
- High BMR, unexplained weight loss, hot, very agitated, tachycardia, exophthalmos (increased fluid behind eyes)
- Often due to tumor of thyroid gland > can be treated with radioactive iodine
What is the location of the parathyroid glands?
Posterior side of thyroid gland
What is the function of the parathyroid glands?
Makes parathyroid hormone (PTH)
^ Responsible for controlling blood calcium levels
What are the adrenal cortex hormones (3 different groups)
Aldosterone, cortisol, sex hormones (androgens)
Contrast hyper- and hypo parathyroidism
Hyperparathyroidism
^ Happens due to tumor or enlargement of one or more of the parathyroid glands
^ Too much PTH = too much calcium ion being released from bones, decreasing bone density > fractures
Hypoparathyroidism
^ Fatal
^ Blood calcium levels drop to a very low level
^ Muscle spasms, irritability are presenting symptoms
Describe the function of aldosterone and where it comes from
- The mineralocorticoid-secreting area of the adrenal cortex secretes aldosterone
- Aldosterone is responsible for sodium ion and water balance and blood pressure
^ Target: kidney tubules
Describe the function of cortisol and where it comes from
The glucocorticoid-secreting area of the adrenal cortex makes cortisone and cortisol
- Cortisol responds to stress by increasing blood glucose and blood pressure in an attempt to get you through the stressful situation
What produces the two pancreatic hormones? Are they under endocrine or exocrine function?
- Pancreatic islet cells
- Endocrine
What hormone is secreted by the pineal gland and what is its function?
- Responsible for sleep and wake cycles
- Produces and secretes melatonin
^ Peaks during the night
Define glycogenolysis and gluconeogenesis
- Glycogenolysis: converting glycogen to glucose
- Gluconeogenesis: making new glucose from non-carbohydrate sources (amino acids, etc.)
What are the two pancreatic hormones? Describe them
Alpha cells
- Produce glucagon in response to low
blood glucose
- Alpha cells would be stimulated if you
skip breakfast
- Stimulates: liver release of glucose
(stored as glycogen), glycogenolysis
(converting glycogen to glucose) and/or
gluconeogenesis (making new
glucose) > sends glucose to blood >
increased blood glucose!
Beta cells
- Insulin
- In response to high blood glucose
- Stimulates: cell membrane receptors
for glucose, liver storage of glucose
(glycogen)
Where is the adrenal medulla (compared to cortex) and what are its hormones and their functions?
- Inner portion of the adrenal cortex
- Responsible for short term stress response
- Makes epinephrine (adrenaline) and norepinephrine
^ Increased HR, increased BP, liberation
of glucose into bloodstream,
increased airflow via dilation of
bronchioles, etc.
^ Stimulated during fight or flight
Contrast type I and type II diabetes mellitus
Type 1: beta cells are destroyed
^ Autoimmune disease
^ Juvenile onset
^ Insulin dependent > must monitor
blood sugar levels and intake, must
administer insulin to make cells take up
glucose
Type II
^ Typically, adult onset
^ Resistant to insulin
^ In the beginning, beta cells are still
making insulin, but the receptors are
not sensitive to it/are resistant to it
^ Glucose in the bloodstream remains
high
Differentiate the components of blood in a centrifuged tube
- Plasma (yellowish, on top)
- Leukocytes/WBC, platelets (white band, interface between top and bottom layers)
- Erythrocytes/RBC (densest, at bottom layer, red)
Describe the composition of plasma; what protein is in the highest concentration and state the function of this protein
- About 55% of blood is plasma
- About 90% of plasma is water
- Salts (electrolytes) are found in plasma
- Most abundant plasma protein: albumin
^ Important for osmotic balance (keeps
osmolarity relatively high so that blood
volume is maintained) - Also contains fibrinogen (clotting factor) and globulins (defending antibodies)
What type of tissue is blood? Describe the composition
Connective tissue
^ Fluid matrix (plasma)
^ Bright red: high levels of oxygen
^ Dull red: low levels of oxygen
State the functions of blood
- Transport of substances
^ Nutrients: glucose, fatty acids, amino
acids, vitamins
^ Waste products of metabolism: urea,
uric acid
^ Respiratory gases: O2 and CO2
^ Hormones: steroids and thyroid
hormones are carried by plasma
proteins - Body heat distribution
Contrast the structure and function of erythrocytes and leukocytes
- Erythrocytes: RBCs, biconcave discs, very small, full of hemoglobin
^ Function is to transport oxygen and a
small amount of CO2 - Leukocytes: a round shape with a distinct center membrane (nucleus), colorless, appear light pink/purple under a microscope
^ Function is defense
Describe the process of erythropoiesis (see also the pathway later in the PPT), include the location and hormone/source of the hormone that regulates the process
- Erythropoiesis is the process of RBC formation
- Takes place in the red bone marrow (which makes all formed elements)
- Erythropoietin (EPO, hormone) comes from kidneys and stimulates erythropoiesis in response to reduced oxygen levels in the blood
- Stimulus (low blood O2)
- Kidneys (and liver, to a smaller extent) release erythropoietin
- EPO stimulates red bone marrow
- Enhanced erythropoiesis increases RBC count
- O2 carrying ability of blood increases
What are the stimuli for erythropoiesis?
Low blood O2
^ Decreased RBC count
^ Decreased amount of hemoglobin
^ Decreased availability of O2
It takes _____ days for a single RBC to reach maturity/pass through all developmental stages
3-5
Describe the structure and function of hemoglobin
- Structure: made up of 4 amino acid chains: 2 beta and 2 alpha globin chains
^ Heme group in center of each chain
where an iron atom can be found - Function: transporting oxygen from lungs to tissues through the blood, facilitates return of carbon dioxide
Define leukemia
Very elevated WBC numbers because the bone marrow has become cancerous, all are immature/non-functional in typical way
Define anemia. What can it be caused by?
- Reduced oxygen-carrying capability of blood
- Can happen due to reduced number of erythrocytes (hemorrhage, hemolysis, vitamin B deficiency) or reduced hemoglobin (iron deficiency)
Contrast the different types of anemia discussed in lecture
- Pernicious anemia: vit B deficiency
- Aplastic anemia: bone marrow is not producing adequate numbers
- Sickle cell anemia: genetically inherited disease, single amino acid change, sickle shape instead of normal biconcave shape, blood flow is blocked
Define positive chemotaxis
An attraction of WBC to areas of tissue damage/inflammation
Define leukocytosis
The increase in WBC number in response to infection or inflammation
State the overall function of leukocytes
Defense!
What is polycythemia and why is it a dangerous condition?
- An abnormal/excessive increase in RBC numbers
^ Could be cancer of the bone marrow
^ Could occur naturally in areas of high
altitude - Can be dangerous because it can cause the blood to become much more viscous and sluggish, leading to cardiac arrest
What are the two groupings of leukocytes? Contrast the structure
- 2 groupings: granulocytes, agranulocytes
- Granulocytes: granules in cytoplasm that carry inflammatory substances
- Agranulocytes: without granules
Define diapedesis
The passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation
What are the types of granulocytes? Describe them
- Neutrophils: most abundant kind of WBC, have a multilobed nucleus, involved in acute infections, called bacteria slayers because they have a phagocytic function
- Eosinophils: bilobed nucleus, reddish-orange color when stained, elevation of eosinophils indicate the presence of parasitic worms and/or allergy attacks, shoot out digestive enzymes to kill parasitic worms
- Basophils: least numerous, bilobed nucleus, have very dark/coarse granules that make the nucleus hard to discern, stains dark blue, release histamine at sites of inflammation
Define leukopenia
An abnormally low WBC count, commonly caused by drugs
