Week 4: Recorded Lectures Flashcards
Hydrophilic Signalling Factors
- Water loving
- When synthesized cannot cross cellular membranes
- Can be stored and released on demand
Hydrophobic Signalling Factors
- Water hating
- When synthesized can cross cellular membranes
- Can’t be stored so they diffuse from the cell
Hydrophilic Factors - Travel
Travel easily, dissolved in the extracellular fluid
Hydrophobic Factors - Travel
Have to travel attached to a water-soluble carrier
Water Soluble
- Can’t get into cell so they have to trigger a response by binding to a receptor on the cell membrane
Fat Soluble
Freely diffuse across cell membrane, so receptors are inside the cell
Elements of Endocrine Signaling Pathway
- Synthesis
- Secretion
- Transport
- Reception
- Transduction
- Response
Synthesis (step 1)
A hormone is synthesized in an endocrine gland
Secretion (step 2)
- Hormones are released
- Lipid soluble hormones diffuse through cellular membranes
- Water soluble hormones are released via the ER-Golgi system using exocytosis
Transport (step 3)
- Hydrophilic hormones need no carriers, they dissolve in the blood
- Hydrophobic hormones bind to proteins in the blood, which carry them to target tissues
Reception (step 4)
- Binds to a receptor at the target tissue
- 2 things can occur: conformational change, ligand specificity
Conformational Change
Binds hormone on outside causing change in shape to the receptor
Ligand specificity
The ability of a receptor to bind only to a specific ligand
Phytoestrogens
- Estrogen-like compounds found in plants
- In many vertebrates, males that eat too many plants may experience a feminization
Transduction (step 5)
- Process of converting a signal into a cellular response
- Amplifying the signal
- Examples: cascades and 2nd messengers
Antagonistic Hormones
Pairs of hormones that have opposite effects to maintain balance in the body
What 2 main hormones control glucose levels?
- Insulin
- Glucagon
Insulin
Reduces blood glucose levels when they’re high
Glucagon
Increase blood glucose when they are low
Hypothalamus gland
Collection of neurons
Exocrine glands
Secretes products outside of the body
Endocrine glands
Secretes hormones into the circulating fluids, blood or ECF
Posterior pituitary
Collection of terminal axons coming from hypothalamus
Anterior pituitary
Communicates with hypothalamus via portal vessel
Portal vessel
Blood vessels that don’t fit definition of artery or vein
Adrenal Glands
- Found on the kidneys
- Secrete epinephrine apart of adrenal response
Myocytes
- Muscle cells
- Contractile cells in muscles regulate physiological systems and are essential for homeostasis
Microtubules
- Biggest
- Tubulin polymers
- Serve as tracks for motor proteins to walk
Microfilaments
- Smallest
- Actin filaments
- Maintain cell shape, enable cell movement, and assist in cell division.
Intermediate Filaments
- Middle size
- One of several proteins like keratin
Myosin & Actin
- In all eukaryotic cells and all animal cells as apart of the cytoskeleton
- Myosin walk along actin filaments
Kinesin
- walks along microtubule tracks
- Recognize polarity of microtubules. One walks towards (+) end, and the other walks toward (-) end
Dynein
- walks along microtubule tracks
- Recognize polarity of microtubules. One walks towards (+) end, and the other walks toward (-) end
Myosin II
- made up of a head, tail and neck
- Proteins @ neck help regulate catalytic properties of myosin
Thin filaments
- actin filaments in a myocyte
- arranged into an array
- decorated with actin binding proteins: troponin and tropomyosin
Thick filaments
- Myosin’s arranged into bundles
Smooth muscle
- Has thick and thin filaments
- They are scattered throughout the cell in all directions
Sarcomeres
- Basic contractile units of muscle fibre
Myofibrils
- long, cylindrical structures found within muscle fibers
- contain actin and myosin, enabling muscle contraction
Actomyosin ATPase
- Enzyme that hydrolyzes ATP to provide energy for muscle contraction
Troponin
protein complex bound to actin that controls muscle contraction by responding to calcium ions
Tropomyosin
protein that blocks myosin-binding sites on actin filaments, preventing contraction until troponin induces a change
Innervation patterns
Determine where a muscle contracts once or has a sustained contraction
Muscle recruitment
Determines the contractile force
Antagonistic groups
- pairs of muscles that work opposite to each other, where one contracts while the other relaxes
- Ex. Biceps and triceps
