week 4 (homeostasis, endocrine/nervous system) Flashcards
homeostasis
maintaining conditions at a certian level in the body
feedback system
consist of a: stimulus (message) receptor (recievier) control centre (processes info from reiever) effector (musucle, gland, ect) reponse(alters the condition)
negative feedback
the response reduces the stimulus
reverses a change in a controlled condition
positive feedback
reinforces a change in a controlled condition
what is the difference between positive and negative feedback loops
A negative feedback system reverses
a change in a controlled condition while Unlike a negative feedback system, a
positive feedback system tends to strengthen or reinforce a change
in one of the body’s controlled conditions
how do the nervous and endocrine feedback adjustment mechanisims help with body homeostasis
it helps the body with homeostasis because it uses hormones to control thigns like blood calclium levels
feedback loops also help with reguling reflexes
components of negitive feedback loops
stimulus, sensor, control centre, effectors, response
stimulus
the change in the internal environment (movement away from the set point)
eg. body temp rising
sensor
the cells/tissue or organ which detects the stimulus and initiates a signal which will need to go to the control centre
eg. temoreceptor area of the hypothalamus or skin thermoreceptors will intitae an impulse which travels on sensory neaurons to the control centre
control centre
cell/tissue or organ which recieves signal which will need to go to the control centre
a second area of the hypothalamus called the heat losing center which initiates impulses on motor neurons to the effectors
effectors
cells/tissue or organs that recieve the signal from the contorl centre. this alters the activity of the effector. the chsnge in effector activity causes the system ti move back to the set point
eg. sweat glands release sweat on skin surface evaporation causes cooling
eg. skin capillaries dilate, increasing blood flow close to body surface. increase loss of heat
response
the result of the negitive feedback mechanism. theis result will always be the opposite to the original stimulus, causeing movement back to the setpoint
eg. the body temp is falling back to the set point
endocrine system
acts to help coordinate cell activity in tissues/organs
involves actions of hormones
hormones are transported via the blood to target glands and tissues
individual hormones are very specific in their action and can profoundly alter physiological activity of their targets
hormones
chemicals synthesized and released by endocrine glands and hormone secreting cells
what is the relationship between the nervous and endocrine system
work together to cooridinate the activity levles of the tissues/organs in the body
each system responds to specific changes in internal environment
nervous system is quick and initiates nerves impulses to alter tissue or organ activity
endocrine system responses slower and iniate a more sustained change in its target tissue
endocrine gland
The secretions of endocrine glands called hormones, enter the interstitial
fluid and then diffuse into the bloodstream without flowing through
a duct
endocrine cells
characterized by the secretion of various hormones (signaling molecules) to the blood.They produce hormones in response to nervous stimuli (changes in membrane potential). Examples are intestinal endocrine cells, cells in the adrenal medulla and pancreatic endocrine cells
circulating hormones
Most endocrine hormones are circulating hormones—they pass
from the secretory cells that make them into interstitial fluid and
then into the blood
What is the target cell of a hormone
h look at 5
what is the difference between exocrine and endocrine glands
The secretions of endocrine glands called hormones, enter the interstitial
fluid and then diffuse into the bloodstream without flowing through
a duct
secrete their products into ducts that carry the
secretions into body cavities, into the lumen of an organ, or to the
outer surface of the body. Exocrine glands include sudoriferous
(sweat), sebaceous (oil), mucous, and digestive glands
pituitary gland
by the thalamus in the brain
secretes alot lol
thyroid gland
on the trachea/larynx
secretes T3, T4 and Calcitonin
parathyriod gland
on posterior side fo thyriod
parathyriod hormone (PTH)
pancreas
pancrease in the admonen
scretes insulin and glucagon
adrenal cortex
on kidneys
secretes glucocrticoids (mainly cortisol) mineralocorticoids (mainily aldosterone) androgens(small amounts)
adrenal medulla
on kidneys
epinephrine (adenaline)
norepinephrine (noradrenaline)
ovaries
in womans reproduction system
secretes estrogen and progesterone
testes
in males reproductive system
secretes teststerone
thymus
thymus is farer down your espoguous from your thyroid
secretes thymosin
relationship between the hypothalamus and the pituitray gland
hypothalamus produces serveral hormones and two types of important connections to the pitiuotary
- hypothalamus produces horomones which are carried (by blood vessels) directly to the anterior pituitary (adenohypophysis) where they simulate or inhibit secretion of anterior pituitary hormones
- axons of neurosecretory cells extend from the hypothalalmus into the posterior pituitary (neaurohypohysis) where as a result of action potentials, they realease the hormones of the posterior pituitary
Growth Hormones (GH) or Somatotrophic Hormone (STH)
name of releasing and or inhibiting factors released by the hypothalamus:
GHRH and inhibited by PIH
the means by which these chemical factors reach the anterior pituitary:
the target gland/tissue that each hormone acts on:
liver, bone, muscules
the specific hormone action on the target gland/tissue:
induces targets to produce insulin-like gorwth factors (IGF). IGF stimulate body growth and higher metabolic rate
Thyriods-Simulating Hormone (TSH)
name of releasing and or inhibiting factors released by the hypothalamus:
TRH
the means by which these chemical factors reach the anterior pituitary:
the target gland/tissue that each hormone acts on:
Thyroid Gland
the specific hormone action on the target gland/tissue:
Simulates the release of thyroid hormone (TH). TH regulates metabolism
adrenocrtiocotropic hormone (ACTH
name of releasing and or inhibiting factors released by the hypothalamus:
CRH
the means by which these chemical factors reach the anterior pituitary:
the target gland/tissue that each hormone acts on:
Adrenal Glands
the specific hormone action on the target gland/tissue:
induces targets to produce glucocorticoids, which regulate metabolism and the stress response
follicle-stimulating hormone (FSH)
name of releasing and or inhibiting factors released by the hypothalamus:
GnRH
the means by which these chemical factors reach the anterior pituitary:
the target gland/tissue that each hormone acts on:
reproductive system
the specific hormone action on the
target gland/tissue:
stimulates production of sperm and eggs
Luteinizing hormone (LH) (interstitial cell stimulating hormone - ICSH)
name of releasing and or inhibiting factors released by the hypothalamus:
GnRH
the means by which these chemical factors reach the anterior pituitary:
the target gland/tissue that each hormone acts on:
reproductive system
the specific hormone action on the target gland/tissue:
stimulates producttion of sec hormones by gonands
oxytocin
site of syntheis and release :
the means by which these hormones reach the posterior pituitary:
control centre for their release:
Neurosecretory cells of hypothalamus secrete OT in
response to uterine distension and stimulation of
nipples.
the specific hormone action on the target gland/tissue:
Stimulates contraction of smooth muscle cells of
uterus during childbirth; stimulates contraction of
myoepithelial cells in mammary glands to cause
milk ejection.
antidiuretic hormone
site of syntheis and release :
the means by which these hormones reach the posterior pituitary:
control centre for their release:
Neurosecretory cells of hypothalamus secrete ADH
in response to elevated blood osmotic pressure,
dehydration, loss of blood volume, pain, or stress;
inhibitors of ADH secretion include low blood
osmotic pressure, high blood volume, and alcohol.
the specific hormone action on the target gland/tissue:
Conserves body water by decreasing urine volume;
decreases water loss through perspiration; raises
blood pressure by constricting arterioles.
How thyroid effects basal metabolic rate
Secretion is increased by thyrotropin-releasing
hormone (TRH), which stimulates release of
thyroid-stimulating hormone (TSH) in response
to low thyroid hormone levels, low metabolic
rate, cold, pregnancy, and high altitudes; TRH
and TSH secretions are inhibited in response to
high thyroid hormone levels; high iodine level
suppresses T3/T4 secretion.
increaases basal metabolic rate
How thyroid effects tissue growth and development
Thyroid hormones are necessary for the development of the nervous system: They promote synapse formation, myelin production,
and growth of dendrites. Thyroid hormones are also required for
growth of the skeletal system: They promote formation of ossification centers in developing bones, synthesis of many bone proteins,
and secretion of growth hormone (GH) and insulin-like growth
factors (IGFs).
How thyroid effects the nervous system
Thyroid hormones are necessary for the development of the nervous system: They promote synapse formation, myelin production,
and growth of dendrites. Thyroid hormones are also required for
growth of the skeletal system: They promote formation of ossification centers in developing bones, synthesis of many bone proteins,
and secretion of growth hormone (GH) and insulin-like growth
factors (IGFs).
how do thyroid gland and parathyroid gland work together to achieve calcium homeostatis
A higher-than-normal level of calcium ions (Ca2+) in the blood
stimulates parafollicular cells of the thyroid gland to release
more calcitonin.
Calcitonin inhibits the activity of osteoclasts, thereby decreasing
the blood Ca2+ level.
A lower-than-normal level of Ca2+ in the blood stimulates chief
PTH promotes resorption of bone extracellular matrix, which
releases Ca2+ into the blood and slows loss of Ca2+ in the urine,
raising the blood level of Ca
cells of the parathyroid gland to release more PTH.
function of nervous system
first sensory receprors of the nervous system sense any changes within the body or in the outside enironment. these receptors initiate a nerve impulse in response to this change
second integrating centres of the nervous system reieve the impulse, interpet the changes and initiate a response.
third, the response involves the transfer of a nerve impulse to a musscle or gland called the eggecyor to change its activity
central nervous system
consists of the brain and spinal cord
peripheral nervous system
contains sensory neurons
motor neurons
motorneurons contain:
somaitc NS and autonomic NS
autonomic NS contains:
parasympathic divison and sympathic divison
brain
reieves and processes sensory information, intiates responses, stores memories, generates thoughts and emotions
spinal cord
conducts signals yo and from the brain, controls relex activites