UNIT A (NERVOUS AND ENDORCRINE SYSTEM) Flashcards
What does the nervous system do in regard to homeostasis?
The nervous system regulates body structures and processes to maintain homeostasis despite fluctuations in the internal and external environment.
What are the two divisions of the nervous system?
Central nervous system (CNS)
Peripheral nervous system (PNS)
CNS
Consists of the nerves of the brain and spinal cord and acts as a coordinating centre for incoming and outgoing information.
PNS
Consists of nerves that carry information between the organs of the body and the central nervous system. Further subdivided into somatic and autonomic
nerves.
Division on the Nervous System (Diagram)
Gilial Cells
Neuroglial cells, are nonconducting cells and are important for the structural support and metabolism of the nerve cells. Has different types of myelin sheath. (Schwann cells are a type of gilial cell that form the myelin sheath around axon).
Neurilemma
Outer layer of Schwann cells in the PNS.. Delicate membrane that surrounds the axon of some nerve cells. Formed by the Schwann cells and promotes the regeneration of damaged axons. Not all nerve cells that have a myelin sheath have a neurilemma.
Nerves within the brain that contain myelinated fibres are called white matter because the myelinated axons are whitish in appearance. Other nerve cells within the brain and spinal cord, referred to as the grey matter, lack a myelin sheath.
Myelin Sheath
Insulated covering over the axon of a nerve cell, located in the PNS, made up of Schwann cells that form neurilemma.
Neuron
Nerve cell that conducts nerve impulses
Dendrite
Projection of cytoplasm that carries impulses toward the cell body. Conduct nerve impulses towards cell body.
Axon
Extension of cytoplasm that
carries nerve impulses away from
the cell body
Nodes of Ranvier
Regularly occurring gaps between sections of myelin sheath along the axon.
Sensory Neurons
Located in the PNS, neurons that
carries impulses to the central
nervous system; also known as
afferent neuron.
Ganglia
The cell bodies of sensory neurons are
located in clusters called located outside of the spinal cord.
Interneurons
Located in the CNS, link neurons to other neurons. Found only in the brain and spinal cord, the interneurons (also known as association neurons) integrate and interpret the sensory information and connect sensory neurons to outgoing motor neurons.
Motor Neurons
(also known as efferent neurons) relay information to the effectors, which is the cell or organ that responds to the stimulus. Muscles, organs, and glands are classified as effectors because they produce responses.
Reflex Arc
Before it reaches your brain, sensation detected by receptors and a nerve impulse carried to the spinal cord. The sensory neuron passes the impulse on to an interneuron, which, in turn, relays the impulse to a motor neuron. The motor neuron causes the muscles in the hand to contract and the hand to pull away. All this happens in less than a second, before the information even travels to the brain.
Pupillary Reflex
Check for reflexes, healthy nervous system!
All or nothing
No matter what the intensity or duration of a stimulation, a nerve or muscle will respond completely or not at all. No such thing as a too big or less impulse.
BUT threshold level is not a fixed value and can be influenced by ion concentration, neurotransmitters, diseases, disorders or conditions.
Action Potential
The voltage difference across a nerve cell
membrane when the nerve is excited. The resting membrane normally had a potential somewhere near -70 mV (millivolts); however, when the nerve became excited, the potential on the inside of the membrane registered -55mV. This reversal of potential is described as an action potential.
Resting Potential
Voltage difference across a nerve cell membrane when it is not transmitting a nerve impulse (usually negative).
Plasma Membrane During Resting Potential
Higher concentration of
potassium ions (K+) inside the cell and a higher concentration of sodium ions (Na+) outside the cell. The movement of K+ is mainly responsible for creating the electrical potential. Sodiuum-Potassium exchange pump exchanges 3 Na+ ions for 2 K+ ions. Plasma membranes are selectively permeable; ions cannot cross the bilayer by simple diffusion. Instead, they enter cells by facilitated diffusion, passing through gated ion channels that span the bilayer. (If ion concentrations were determined only by diffusion, eventually the concentrations of sodium and potassium would equalize across the membrane. This does not happen because the sodium-potassium pump in the membrane moves potassium back into the cell and sodium back out of the cell through active transport.)
Polarized Membrane
Excess positive ions accumulate along the outside of the nerve membrane, while excess negative ions accumulate along the inside of the membrane. The resting membrane is said to be charged and is called a polarized membrane. A charge of -70 mV indicates the difference between the number of positive charges found on the inside of the nerve membrane relative to the outside. (A charge of -90 mV on the inside of the nerve membrane would indicate even fewer positive ions inside the membrane relative to the outside.)
Impulse Order
- Resting Potential: -70mV
- Action Potential: -55mV
- Depolarization: Diffusion of sodium ions into the nerve cells, resulting in a charge reversal. Cell membranesare more permeable to Na+ than K+, opening sodium channels while potassium channels remain closed. All the way to +35mV
Repolarization: The process of restoring the original polarity of the nerve membrane, Na+ channels close and K+ channels open. As K+ leaves from the inside of the cell, the inside becomes more negative, outside becomes more positive, and because K+ channels are slow to close, causes hyperpolarization! - Hyperpolarization: Condition in
which the inside of the nerve cell
membrane has a greater negative
charge than the resting membrane;
caused by excessive diffusion of
potassium ions out of the cell. - Refractory Period: Recovery time
required before a neuron can
produce another action potential. MUST return to resting potential before generating another action potential!
Movement of Action Potential is through
When axons are myelinated, nerve impulses travel by saltatory conduction. The flow of ions across the cell membrane can only happen at the nodes and so action potentials have to “jump” from node to node. This causes a nerve signal to be transmitted down an
axon much faster.
Order of travel
Dendrites, cell body, axon hillock, axon, myelin sheath, nodes of Ranvier, axon terminals, synapse.
Threshold Level
Minimum level of a
stimulus required to produce a
response
All-or-none-response
A nerve or muscle fibre responds completely or not at all to a stimulus.
Synapse
A region between neurons, or between neurons and effectors; also known as the synaptic cleft. Rarely involve just two neurons!
Neurotransmitters
Chemical messenger released by the
presynaptic neuron that binds to receptors on the postsynaptic neuron.
Presynaptic Neuron
A neuron that carries impulses to the synapse.
Postsynaptic Neuron
Neuron that carries impulses away from the synapse.
Diffusion of Neurotransmitters
Begins by Exyocytocis of Neurotransmitter. Diffusion is a slow process. Not surprisingly, the greater the number of synapses over a specified distance, the slower the speed of transmission. This may explain why you react so quickly to a stimulus in a reflex arc, which has few synapses, while solving biology problems, which involves many more synapses, requires more time.
Acetylcholine
Acts as an excitatory neurotransmitter on many postsynaptic neurons by opening the sodium ion channels. With the sodium channels open, the postsynaptic neuron would remain in a constant state of depolarization. Constant state of contraction!!
Although acetylcholine can act
as an excitatory neurotransmitter on some postsynaptic membranes, it can act as an inhibitory neurotransmitter on others.
Cholinesterase
An enzyme, which breaks down acetylcholine, that is released from presynaptic membranes in the end plates of neurons shortly after acetylcholine. Once acetylcholine is destroyed, the sodium channels close, and the neuron begins its recovery phase. Many insecticides take advantage of the synapse by blocking cholinesterase.
Excitatory Neurotransmitter (depolarization)
Increase membrane permeability to Na+; sodium gates open and sodium ions rush into the axon; the membrane becomes depolarized; action potential generated. (Acetylcholine, adrenaline/ epinephrine which stimulates sympathetic neurons).
Inhibitaory Neurotransmitter (hyperpolarization)
Increase membrane permeability to K+; potassium channels open, and membrane becomes hyperpolarized which means it is more difficult to generate an action potential. The inside of the axon becomes even more negatively charged. Prevent postsynaptic neurons from becoming active (GABA).
Can an action potential be generated by both excitatory and inhibitory?
No.
Excitatory signals make an action potential more likely by depolarizing the membrane and bringing the potential closer to the threshold.
Inhibitory signals make an action potential less likely by hyperpolarizing the membrane and moving the potential further from the threshold.
Action potential generation depends on the overall balance of excitatory and inhibitory inputs. If the excitatory input is strong enough to overcome the inhibitory input, an action potential will be generated.
**
The production of an action potential in neuron D requires the sum of two excitatory neurons. This principle is referred to as summation.
Parkinson’s disease
Involuntary muscle contractions and tremors is caused by inadequate production of dopamine.
Alzheimer’s disease
Associated with the deterioration of memory and mental capacity, has been related to decreased production of acetylcholine.
Meninges
Protective membranes
that surround the brain and spinal
cord
Cerebrospinal fluid
Cushioning fluid that circulates between the innermost and middle membranes of the brain and spinal cord; it provides a connection between neural and endocrine systems.
Spinal Cord
Carries sensory nerve messages from receptors to the brain and relays motor nerve messages from the brain to muscles, organs, and glands. Emerging from the skull through an opening called the foramen magnum, the spinal cord extends downward through a canal within the backbone.
Dorsal Root
Brings sensory information into the spinal
cord.
Ventral Root
Carries motor information from the spinal cord to the peripheral muscles, organs, and glands (effectors).
Grey Matter
Cell bodies, dendrites, short unmyelinated axons. Outside areas of the brain forms the H-shaped core of the spinal cord (inside).
White Matter
Myelinated axons that run together in tracts. Inner region of some areas of the brain and outer area of the spinal chord.
Brain divisions
- Hindbrain
- Midbrain
- Forebrain
Layers of Mengies, outside to inside
- Dura mater
- Archnoid Master
- Pia mater
What makes up the forebrain?
Cerebrum
Cerebral Cortex
Corpus Callosum
Thalamus
Hypothalamus
Olfactory Bulbs
(frontal lobe, parietal lobe, occipital lobe, temporal lobe).
What makes up the hindbrain?
Cerbellum
Medualla Oblongata
Pons
What makes up the midbrain?
Found above the pons
Directs and processes visual and auditory info between hindbrain and forebrain
Cerebrum
Divided into left and right hemispheres. Largest and most highly developed part of the human brain, which stores sensory information and initiates voluntary motor
activities.
Cerebral Cortex
Outer layer of the cerebral hemispheres
Corpus Callosum
Nerve tract that joins the two cerebral hemispheres.
Thalamus
Area of brain that coordinates and interprets sensory information and directs it to the cerebrum.
Hypothalamus
Area of the brain that coordinates many nerve and hormone functions. Plays a large role in maintaining the body’s internal equilibrium. A direct connection between the hypothalamus and the pituitary gland unites the nervous system with the endocrine system.
Regulates internal environment, blood pressure, hunger, thirst, sleep, body temperature, water balance and plays a role in the fight or flight response!
Olfactory Bulb
Area of the brain that processes information about smell; one bulb in each hemisphere.
Cerebellum
Part of the hindbrain that controls limb movements, balance, and muscle tone.
Pons
Region of the brain that acts
as a relay station by sending nerve
messages between the cerebellum
and the medulla.
Medulla Oblongata
Region of the hindbrain that joins the spinal cord to the cerebellum base of brainsteam, connects brain with spinal cord; one of the most important sites of autonomic nerve control. Involuntary muscle action, breathing movements, the diameter of the blood vessels, heart rate, swallowing, coughing.
Alzheimer’s Disease
Deterioration of thinking and of memory
Divison’s of the PNS
The sensory-somatic and the autonomic nervous system. Both of these systems are composed of sensory neurons, which run from stimulus receptors to the central nervous system (CNS), and motor neurons, which run from the CNS to muscles or organs that take action. The sensory somatic nervous system senses and responds to external stimuli, and the autonomic nervous system responds to internal stimuli.
The Sensory-Somatic System
Brings information about the external environment to the CNS and sends information back to the skeletal muscles. Voluntary control but also include the involuntary reflex arcs.
12 pairs of cranial nerves (nerves that originate in the brain) and 31 pairs of spinal nerves.
The Autonomic Nervous System
Brings information about the body’s internal environment to the CNS and carries signals back to regulate the internal environment. Controls smooth muscle, cardiac muscle, the internal organs, and glands. This control is involuntary.
Two groups of motor neurons the autonomic nervous system uses?
- preganglionic neurons, run from the
CNS to a ganglion where they connect with a second group (below) - the postganglionic neurons, which then run to the target organ, muscle, or gland
What is the autonomic system made up of?
- Sympathetic Nervous System: Nerve cells of the autonomic nervous system that prepare the body for stress.
- Parasympathetic Nervous System: Nerve cells of the autonomic
nervous system that return the
body to normal resting levels after
adjustments to stress.
Anatomy of sympathetic nerves
Short preganglionic nerve and a longer postganglionic nerve. The preganglionic nerves release acetylcholine, postganglionic nerve releases norepinephrine. Come from the thoracic vertebrae (ribs) and lumbar vertebrae (small of the back).
Anatomy of parasympathetic nerves
Long preganglionic nerve and a shorter postganglionic nerve. The preganglionic release acetylcholine and the postganglionic nerve releases acetylcholine and/or nitric oxide. Exit directly from the brain or from either the cervical (the neck area) or caudal (tailbone) sections of the spinal cord. The Vagus nerve (vagus meaning “wandering”) innervates the heart, bronchi of the lungs, liver, pancreas, and the digestive tract.
Sensory Adaptation
Occurs once you have adjusted to a change in the environment; sensory receptors become less sensitive when
stimulated repeatedly.
Taste and Smell
Taste: sweet, sour, salt, bitter, and savoury (also called umami), taste receptors concentrated in the taste buds on the tongue.
Nose: works with the tongue!
Three layers of the eyes, outside to inside
- Sclera
-cornea
-aqueous humor - The choroid
-iris
-lens
-ciliary muscles - Retina
-rods
-cones
Sclera
Outer covering of the eye that supports and protects the eye’s inner layers; usually referred to as the white of the eye
Cornea
Transparent part of the
sclera that protects the eye and
refracts light toward the pupil of
the eye by acting like a window.
Aqueous Humor
Watery liquid that protects the lens of the eye and supplies the cornea with nutrients.
Choroid Layer
Middle layer of tissue in the eye that contains blood vessels that nourish the retina.
Iris
Opaque disk of tissue surrounding the pupil that regulates amount of light entering the eye. (uses adaptation)
Lens (anterior chamber and posterior chamber)
Focuses the image on the retina, is found in the area immediately behind the iris.
Ciliary Muscles
Attached to ligaments suspended from the dorsal and ventral ends of the lens, alter the shape of the lens. (uses accommodation)
Vitreous Humor
Contains a cloudy, jellylike material that maintains the shape of the eyeball and permits light transmission to the retina.
Retina
Innermost layer of tissue at
the back of the eye containing
photoreceptors.
Rods (outnumber cones!) (sensory receptor)
Respond to low-intensity light, photoreceptors that operate
in dim light to detect light in black
and white. Sensitive to light intensity!
Cones (sensory receptor)
Require high-intensity light, identify colour, photoreceptors that operate
in bright light to identify colour. Sensitive to color!
Optic Nerve
Carrries the impulse to the central nervous system.
Fovea Centralis
Area at centre of retina where cones are most dense and vision is sharpest. The most sensitive area of the eye, it
contains cones packed very close together. When you look at an object, most of the light rays fall on the fovea centralis. Rods surround the fovea, which could explain why you may see an object from the periphery of your visual field without identifying its colour.
No rods or cones in the area in which the optic nerve comes in contact with the retina. Because of this absence of photosensitive cells, this area is appropriately called the blind spot.
Rhodopsin
The pigment found in the rods of the eye. A long-term vitamin A deficiency can permanently damage the rods.
Cataracts
As the lens hardens, it loses its flexibility. Lens age, protein structure begins to degenerate, becomes opaque and prevents light from passing! Grey and white spots.
Astigmatism
Uneven curvature of cornea or lens. The cornea cannot bend light at the correct focal point, vision is blurred, need unevenly ground glasses.
Glaucoma
Disease of the eye in which increased pressure within the eyeball (aqueous humor) causes a gradual loss of
sight
Nearsightendness (myopia)
Eyeball too long, lens cannot flatten enough to project on retina, image is focused in front of retina, require concave lenses or laser surgery.
Farsightedness (hyperopia)
Eyeball too short, distant images brought into focus behind retina instead on it, light does not meet before reaching retina, require convex lenses/converginglenses where light meets at one point.
Colour Blindness
Lack or deficiency in particular cones
What is the ears job
Hearing and equilibrium
Layers of the ear
- The outer ear
-pinna
-auditory canal - The middle ear
-tympanum/eardrum
-malleus, incus, stapes
-connected to throat by Eustachian tube - The inner ear
-semicircular canals
-vestibule
-cochlea
Pinna
Outer part of the ear that acts
like a funnel, taking the sound from a
large area and channelling it into
a small canal, enhances sound vibrations and focuses them
Auditory Canal
Carries sound waves to the eardrum. Lined with specialized sweat glands that produce earwax, a substance that traps
foreign particles and prevents them from entering the ear.
Tympanic Membrane (eardrum)
Where the middle ear begins. Sound is amplified by concentrating the sound energy from the large tympanic membrane to the smaller oval window.
Tympanum/Eardrum
Round, elastic structure that vibrates in response to sound waves
Ossicles
The malleus (the hammer), the incus (the anvil), and the stapes (the stirrup). Sound vibrations that strike the eardrum are first concentrated within the solid malleus, and then transmitted to the incus, and finally to the stapes.
Oval window
Oval-shaped hole in the vestibule of the inner ear, covered by a thin layer of tissue. Stapes strike the membrane covering the oval window in the inner wall of the middle ear.
Eustachian tube
Extends from the middle ear to the mouth and the chambers of
the nose. Approximately 40 mm in length and 3 mm in diameter, the eustachian tube permits the equalization of air pressure on either side of the eardrum.
The Vestibule
Connected to the middle ear by the oval window, houses two small sacs, the utricle and saccule, which establish the head position. Detect static equilibrium or gravitational equilibrium. Both structures contain otoliths and when the head moves forward/back gravity pulls on otoliths, puts pressure on hair cells and sends a nerve impulse to the brain about your head position.
The Semicircular Canals
Fluid-filled structures within the inner ear that provide information about dynamic
equilibrium or head and body rotation. There are 3 of these fluid-filled loops. Contains stereocilia, and when head rotates the fluid bends stereocilia causing hair cells to send nerve impulses to the cerebellum.
The Cochlea
Contains the Organ of Corti, the basilar membrane. Shaped like a spiralling snail’s
shell and contains rows of stereocilia that run the length of the inner canal. The hair cells respond to sound waves and convert them into nerve impulses. The hair cells respond to vibrations of the basilar
membrane. Vibrations in the fluid on either side of the basilar membrane cause the membrane to move, and the hairs on the cells bend as they brush against the tectorial membrane. The movement of the hair cells, in turn, stimulates sensory nerves in the
basilar membrane. Auditory information is then sent to the temporal lobe of the cerebrum via the auditory nerves.
The inner ear is able to identify
Both pitch and loudness because of the structure of the cochlea. Close to the oval window, the basilar membrane is narrow and stiff. Further into the cochlea, the basilar membrane widens and becomes more flexible.
Treatment for hearing loss
Negative Feedback
The process by which a mechanism is activated to restore conditions to their original state.
Positive Feedback
The process by which a small effect is amplified.
Endocrine Hormones
Chemicals secreted by endocrine glands
directly into the blood.
Lipid Soluble Hormones
Steroid Hormones are composed of cholesterol. Can easily diffuse through the lipid bilayer of cell membranes and once inside the target cell can bind to receptor protein. Activates specific genes and changes cells (estrogen, testosterone and cortisol).
Water Soluble Hormones
Amino-acid-based hormones, cannot easily diffuse across cell membranes and instead bind to a receptor protein on the surface or target cell starting a cascade of reactions inside the target cell (epinephrine targets the conversion of available glycogen into millions of molecules of glucose).
Non target Hormones
Insulin, HGH, epinephrine
Pituitary Gland
Gland at the base of the brain that, together with the hypothalamus, functions as a control centre, coordinating the endocrine and nervous systems.
Releasing Hormones
A peptide produced by the hypothalamus that stimulates the anterior pituitary
gland to release a stored hormone;
also called a releasing factor.
Inhibiting Factor
Chemical that inhibits the production of a hormone by the anterior pituitary gland.
Hormones Summary
Anterior lobe
- thyroid-stimulating hormone (TSH)
thyroid gland
- adrenocorticotropic hormone (ACTH) adrenal cortex
- human growth hormone (hGH)
most cells
- follicle-stimulating hormone (FSH)
ovaries, testes
- luteinizing hormone (LH)
ovaries, testes
- prolactin (PRL)
mammary glands
- melanocyte-stimulating hormone (MSH) melanocytes in skin
Posterior lobe
- oxytocin
uterus, mammary glands
- antidiuretic hormone (ADH)
kidneys
Hormones Affecting Blood Sugar
Cells in the Pancreas and the Adrenal Glands
Pancreas
Contains the islets of Langerhans, which contain beta and alpha cells
Insulin
Produced in the beta cells of the islets of Langerhans and is released when the
blood sugar level increases. Causes cells of the muscles, the liver, and other organs to become permeable to glucose to help move the glucose from the blood into your cells. In the liver, glucose is converted into glycogen, the primary storage form for glucose. This enables the blood sugar level to return to normal. In this way, insulin helps maintain homeostasis.
Glucagon
Produced in the alpha cells of the islet of Langerhans when blood sugar levels are low. Glucagon promotes the conversion of glycogen to glucose, which is released into the blood. As glycogen is converted to glucose in the liver, the blood sugar level returns to normal.
From body cells to blood cells!
ADH
A hormone that causes the kidneys to increase water reabsorption. It is released in response to high blood osmolality (high salt concentration). If a concentrated salt solution is injected, it would increase the osmolality of the blood, leading to the release of ADH to help conserve water and reduce the concentration of salt in the bloodstream. This allows more water to be reabsorbed from the urine back into the bloodstream to concentrate the urine and reduce the osmolality of the blood, thereby lowering the salt concentration in the bloodstream and restoring balance.
Diabetes Mellitus Type 1
Occurs when the pancreas is unable to produce insulin because of the early degeneration of the beta cells in the islets of Langerhans. Diagnosed in childhood, and people who have it must take insulin to live.
Diabetes Mellitus Type 2
Decreased insulin production or ineffective use of the insulin that the body produces. Diagnosed in adulthood and can be controlled with diet, exercise, and oral drugs known as sulfonamides (which are ineffective against type 1 diabetes).
Diabetes Mellitus Type 3
Temporary condition that occurs in 2 %
to 4 % of pregnancies. It increases the risk of type 2 diabetes in both mother and child.
Diabetes Insipidus
Inability to produce ADH to reabsorb water into blood! Characterized by large amounts of dilute urine and increased thirst. The amount of urine produced can be nearly 20 litres per day. Reduction of fluid has little effect on the concentration of the urine.
Hyperglycemia
Without adequate levels of insulin, blood sugar levels rise very sharply following meals. Unable to reabsorb all the blood glucose that is filtered through them, so the glucose appears in the urine. Since high concentrations of glucose in the nephrons draw water out
of the plasma by osmosis, people with diabetes excrete unusually large volumes of urine and are often thirsty.
Hormones Involved in Stress Response
Epinephrine
Norepinephrine
Cortisol
ACTH
Aldosterone
Adrenal Medulla (regulated by the nervous system)
Found at the core of the adrenal gland, produces epinephrine and norepinephrine, responsible for short-term stress response.
Adrenal Cortex (regulated by hormones)
Outer region of the adrenal gland that produces glucocorticoids and
mineralocorticoids, responsible for the long-term stress response. Produces 3 types of steroid hormones: the
glucocorticoids, the mineralocorticoids, and small amounts of sex hormones.
What happens during a short-term stress response?
Epinephrine and norepinephrine are released from the adrenal
medulla into the blood. The are released in response to stress!
Blood sugar level rises, glycogen, is converted into glucose, The increased blood sugar level ensures that a greater energy reserve will be available for the tissues of the body. Increase heart rate, breathing rate, and cell metabolism. Blood vessels dilate, iris of the eye dilates.
Cortisol
Hormone that stimulates
the conversion of amino acids to glucose by the liver, raising the level of blood sugar by decreasing insulin and increasing glucagon.
Hypothalamus –> APG –> ACTH –> Cortisol
-negative feedback on the hypothalamus and APG suppresses ACTH and stops the release of cortisol
ACTH
Tropic hormone targets another endocrine gland. The blood carries the ACTH to the target cells in the adrenal cortex to promote cortisol release. Secrete mineralocorticoids and glucocorticoids (among them cortisol).
released from anterior pituitary
Aldosterone
Hormone produced by the adrenal cortex that helps regulate water balance by increasing sodium retention and water reabsorption by the kidneys. Promote the reabsorption of sodium ions (Na⁺) from the urine back into the blood.
As sodium is reabsorbed, water follows passively due to osmosis. This helps to increase blood volume and raise blood pressure.
DANGERS OF BEING SO STRESSED!
CONSTANT HIGH EPINEPHRINE, HIGH CORTISO, IMPAIRED THINKING, HEART DAMAGE, HIGH BP, DIABETES, INFECTION!
Cushing’s Disease
Too much cortisol (hyperglycemia, fat deposits), too much adrenocorticotropic hormone (ACTH) therefore too much cortisol. This causes problems with your body’s hormone balance.
The main problem has to do with too high ACTH (a tumor) causing constant stimulation and release of cortisol. Should be a negative feedback look like other hormones but there is not!
Addison’s Disease
Lack of cortisol (hypoglycemia, weight loss, tiredness), lack of aldosterone (decrease in blood volume/pressure, dehydration, Na+ and K+ imbalance).
Hormones Involved With Metabolism
hGH
Thyroxine
TSH
Calcitonin
PTH
Thyroid Gland
A two-lobed gland at
the base of the neck that regulates
metabolic processes and the rate at which glucose is oxidized. Secretes thyroxine and calcitonin.
Parathyroid Glands
Four peasized glands in the thyroid gland
that produce parathyroid hormone
to regulate blood calcium and
lower phosphate levels. Secretes PTH.
TSH
Stimulus: decreased metabolic rate and cellular respiration, causes thyroxine secretion!
Growth Hormone (hGH)
Produced by the anterior pituitary gland and influences the growth of long bones and accelerates protein synthesis.
Growth hormone is known to have anti-insulin effects, meaning it can reduce insulin sensitivity in tissues and increase blood glucose levels.
Thyroxine (T4)
Hormone produced by the thyroid gland that increases metabolism and regulates growth.
Triiodothyronine (T3)
hormone produced by the thyroid gland that increases metabolism and regulates
growth; contains three iodine atoms.
Hypothyroidism (cretinism)
The thyroid produces low amounts of thyroxine, tired, slow pulse, hair loss, weight gain, and slow metabolism.
Since TSH stimulates thyroxine secretion, constant stimulation causes swelling in the neck, no signal to stop AP.
TOO LESS THYROXINE CAUSES NEGATIVE FEEDBACK AND LOTS OF TSH!
Goiter
When inadequate amounts of iodine
are obtained from the diet, the thyroid enlarges. Without iodine, thyroid production and secretion of thyroxine drops. This causes more and more TSH to be produced and, consequently, the thyroid is stimulated more and more. Under the relentless influence of TSH, cells of the thyroid continue to develop,
and the thyroid enlarges.
Hyperthyroidism (Graves Disease)
Overproduction of thyroxine, anxiety, insomnia, heat tolerance, irregular heartbeat, weight loss, and Graves disease, also cause swelling.
TOO MUCH THYROXINE CAUSES NEGATIVE FEEDBACK AND LESS TSH
Calcitonin
Hormone produced by the thyroid gland that lowers calcium levels in the blood and increase calcium levels in the bones.
Low Calcium Levels in Blood?
Stimulate the release of parathyroid hormone (PTH) from the parathyroid glands and inhibit release of calcitonin from the thyroid. Causes the calcium levels in the blood to increase and phosphate levels to decrease. Kidneys, the intestines, and the bones. Kidneys and intestines to absorb more calcium while promoting calcium release from bone. The bone cells break down,
and calcium is separated from phosphate ions. The calcium is reabsorbed and returned to the blood, while the phosphate is excreted in the urine. This helps conserve much of the body’s calcium that is dissolved in plasma. PTH also enhances the absorption of calcium from undigested foods in the intestine. So, as PTH levels increase, the absorption
of calcium ions also increases.
High Calcium Levels in Blood?
Release of PTH is inhibited and release of calcitonin is stimulated. Intestines, kidneys, and bones reduce the amount of calcium they release to the blood, and calcium levels then begin to fall. This part of the feedback mechanism involving PTH and calcitonin ensures the blood calcium levels will not increase beyond the body’s needs.
More calcium in pee too!
Abnormally high levels of PTH or low levels of calcitonin can cause health problems. A strong, rigid skeleton is necessary for support, so prolonged breakdown of bone is dangerous. High calcium levels can cause it to collect in blood vessels or to form hard structures in the kidneys called kidney stones.
Hormones Released By the Anterior Pituitary
Adrenocorticotrophic hormone (ACTH)
Thyroid-stimulating hormone (TSH)
Luteinising hormone (LH)
Follicle-stimulating hormone (FSH)
Prolactin (PRL)
Growth hormone (hGH)
Melanocyte-stimulating hormone (MSH)
Hormones Released By the Posterior Pituitary
oxytocin and antidiuretic hormone (ADH, or vasopressin)
trh and tsh loop?
Your body controls your thyroid hormone (T3 and T4) levels through a complex feedback loop. Your hypothalamus releases thyrotropin-releasing hormone (TRH), which triggers your pituitary gland to release thyroid-stimulating hormone (TSH), which stimulates your thyroid to release T3 and T4.
negative feedback on thyroid gland…
High TSH levels usually indicate hypothyroidism, and low TSH levels usually indicate hyperthyroidism.
Thyroid-stimulating hormone (TSH) triggers your thyroid to release its hormones, which mainly impact your body’s metabolism. High TSH levels usually indicate hypothyroidism, and low TSH levels usually indicate hyperthyroidism.
Tells your thyroid how much thyroid hormone it needs to make!!
pituitary dwarfism and hormones
hypothyroidism and decreased metabolic rate.
Thyroxine also plays an important role in the growth and development of children by influencing the organization of various cells into tissues and organs. If the thyroid fails to develop properly during childhood, a condition called cretinism can result. In this case, the thyroid produces extremely low quantities of thyroxine, and the person
is said to have severe hypothyroidism. Individuals with cretinism are stocky
and shorter than average, and without hormonal injections early on in life, they
will have mental developmental delays. Adults with hypothyroidism tend to
feel tired much of the time, have a slow pulse rate and puffy skin, and experience
hair loss and weight gain.
gigantism
Hyperthyrodism and increased TOO MUCH metabolic rate.
Untreated acromegaly include cardiovascular diseases, sugar intolerance leading to diabetes, breathing problems, muscle weakness, and colon cancer
