Exam 1 (not all there) Flashcards
Central nervous system
- contains the brain and the spinal chord
- very quick system, immediate response but short effect
- use chemicals to get response (neurotransmitters)
- neurotransmitters are produced in massive amounts in direct travel along neurons
- neurotransmitters bind to receptor with low affinity bc so many are produced
Ex: put hand on hot burner, immediately rip off
Thalamus
- in the brain, above the hypothalamus
- relay station to send motor and sensory signals
Hypothalamus
- endocrine organ/gland in the brain
- right under the thalamus
- highly involved in endocrine function
- works with pituitary gland to maintain homeostasis
- it is the regulator of the body*
- information center, coordinate physiological responses, maintains homeostasis, takes sensory input from environment and creates neuroendocrine response
Ex: controls body temp, thirst, hunger, and other homeostatic systems
What is the difference between male and female endocrine organs
- only the testicles and ovaries/vagina
Endocrinology
- biology dealing with the endocrine system
Function of endocrine glands/organs
- to secrete hormones and trigger a response in the body
Endocrine
- where a gland produces a hormone, releases it into the blood stream and exerts its effect on a DISTANT organ
Paracrine
- where a gland produces a hormone and exerts its effect on a NEARBY target organ
Autocrine
- where an endocrine organ releases a hormone and binds to a receptor back on ITSELF
Intracrine
- when a hormone is produced and never released, it binds to a receptor INSIDE its own organ/gland
4 ways hormones exerted affect target organs
- in order for a hormone to exert an effect it must target an organ and bind to a receptor
- Endocrine
- Paracrine
- Autocrine
- Intracrine
Where can receptors be located
- Cell membrane
- Nuclear membrane
- Inside the nucleus
- Inside the cytoplasm
What can receptors do
- receptors are specific for a hormone, so they bind to a receptor and exert an effect
- much like a switch
- can turn on or off the system
Conditions that can change the effect of a hormone/receptor
- The number of hormones and receptors
- it will affect the result - Antagonists- will reduce an effect and do the opposite of its regular function
- Protagonists- will make the effect larger
- Mutations - varying effects
Half life
- how long does it take for 50% of whatever measure to be taken up by an animal
- hormone half life effects the efficiency of the animal
Are receptors monogamous to one hormone
- no, different hormones have different effects by binding to diff types of receptors
- different subclasses of the same receptor will create a varying effect
Ex: if you give a patient with diabetes insulin it is supposed to lower the sugar levels, but if the receptor is mutated it can have a varying effect
Affinity
- how tightly the hormone binds to its receptor
- aka how easy is the molecule dissociated from the receptor
Ex: carbon monoxide has a high affinity
- it will bind so strongly to the receptor that it will kill you because it wont let go
Specificity
- some hormones will bind to multiple receptors, while others will only bind to a specific one
- Low specificity- hormone will bind to many receptors
- High specificity- hormone will bind to one receptor
Endocrine system responses
- not fast, but response lasts longer
- use chemicals to get response (neurotransmitters)
- indirect travel bc travels along the blood stream
- neurotransmitters bind with high affinity to receptors
Endocrine system and CNS relationship
- compliment to each other
- work together to maintain homeostasis
How do hormones become active
- hormones are synthesized as prohormones or preprohormones
- in order to become active must get rid of the pre and pro part
- the pre and pro keep the hormone in check until it is needed
- when pre/prohormone is released it can run into an enzyme that removes the pre/pro and it will become a bioactive hormone
- if it is missing a matching enzyme it may never become bioactive
Hormones as steroids
- they are lipid soluble (able to pass through the membrane)
- membrane of cells is a phospholipid bilayer with a polar or hydrophilic heads and hydrophobic tails
- cell is selectively permeable and only lipid soluble things can pass through aka steroids
Where is a steroids receptor
- it is intracellular
- therefore, the steroid can fuse through and bind to the hormone inside of the cell
Forms of hormones
- can be dimerized, a heterodimer, a homodimer, homotrimer, heterotrimer
- can be made up of different components
- the receptors can also be made up of dimerization
Ways hormones can remain inactive
- if they do not have a matching enzyme to activate them by losing the pre or pro in the hormone
- some will produce a secretory granule(capsule) to carry the hormone to distant locations and the capsule will inhibit bioactivity
Hormone metabolism
- associated with half life (how long it takes 50% of hormone to be removed by the body)
- metabolic clearance rate (MCR)
- the half life of a hormone is how fast it moves through the plasma and is broken down
What does the half life of a hormone determine
- determines how bioactive the hormone is in the body
- the longer the half life and MCR, means it has a longer bioactive length
Regulation of hormones
- KD -> refers to receptors and dissociation of hormone from the receptor (measure of affinity)
- it is the equilibrium dissociation constant
- the concentration of hormone at which 50% of available receptors are bound to a hormone
- inversely proportional with affinity
- lower KD = higher the affinity of the receptor for the hormone
Negative Feedback
- most common way feedback occurs
- releases hormone that binds to a receptor and shuts something off
Positive Feedback
- less common way feedback occurs
- hormone is released, binds to a receptor and turns something on
Ex: oxytocin and contractions in child birth
- fetus reaches the birth canal, oxytocin triggers contractions and increases its levels until birth occurs
Ex 2: profuse bleeding
- positive stimulus on arteries to have major vasoconstriction
- temporary response and then signal stops
Homeostasis
- body constantly regulates back and forth in flux
- never perfectly level
- feedback and homeostasis work together to maintain levels
Agonist Receptor
- hormone binds and elicits a biological response
Antagonist receptor
- hormone binds and shuts down a response
Ex: beta blocker is an antagonist that blocks a receptor
Ligand gated receptor
- hormone binds to a receptor and a channel opens in the membrane
- allows certain molecules to diffuse through
- ligand is a generic word for something that binds to a receptor, can be a hormone
Intracellular Receptor
- can have a receptor in the cytoplasm, on the nuclear membrane, or on a promoter region inside the nucleus
- cytoplasm is the most common intracellular receptor
G-Protein Linked Receptor Structure
- a class of proteins
- a 7 transmembrane receptor associated with 3 subunits that are heterotrimeric g-proteins
- receptor crosses the membrane 7 times and has a N and C terminal end
- the N terminal is on the outside of the cell and the C terminal is intracellular