Physiology Flashcards
(23 cards)
What is released from the sarcoplasmic reticulum during muscle contraction?
Calcium
Calcium is crucial for initiating muscle contraction by allowing myosin to bind to actin.
What type of structure is the sarcoplasmic reticulum?
Modified endoplasmic reticulum
It surrounds myofibrils and is responsible for calcium storage and release.
What does calcium bind to during muscle contraction?
Troponin
This binding causes the actin filament’s binding site to become exposed.
What is the role of actin in muscle contraction?
It binds to myosin
This binding leads to muscle contraction.
What initiates calcium uptake by the sarcoplasmic reticulum?
Adenosine triphosphate (ATP)
ATP is essential for muscle function and relaxation.
What happens to the binding site on the actin filament in the absence of calcium?
It becomes blocked
This allows for muscle relaxation.
What occurs to ATP production at the time of death?
ATP ceases to be formed
This leads to physiological changes in muscle function.
What effect does the lack of ATP have on myosin cross bridges?
They cannot detach
This results in constant muscle contraction known as rigor mortis.
Fill in the blank: The sarcoplasmic reticulum is responsible for _______ storage and release.
calcium
True or False: Rigor mortis occurs due to the continuous detachment of myosin from actin.
False
Rigor mortis occurs because myosin cannot detach without ATP.
Which hormones are secreted by adrenal medulla?
Epinephrine and norepinephrine
* regulate blood circulation
* metabolism of carbohydrates when body is stressed (fight or flight)
Which hormones are released by the adrenal cortex?
Cortisol and aldosterone
Glucagon is secreted by what cells of the pancreas?
Alpha cells
What are the three factors upon which the passive secretion of aqueous humor depends?
Oncotic pressure, Intraocular pressure, Capillary hydrostatic pressure
These factors are crucial for the processes of ultrafiltration and diffusion in aqueous humor secretion.
What type of cells actively secrete aqueous humor?
Non-pigmented ciliary epithelial cells
These cells are responsible for the active secretion of aqueous humor in the eye.
What processes contribute to the production of aqueous humor?
Active secretion, Passive processes (ultrafiltration and diffusion)
Aqueous humor is produced mainly through active secretion, with passive processes playing a minor role.
True or False: Passive secretion plays a major role in the production of aqueous humor under normal conditions.
False
Most of the formation of aqueous humor occurs as a result of active secretion.
Fill in the blank: Fluid movement into the posterior chamber is favored by the hydrostatic pressure difference between the capillary pressure and the _______.
intraocular pressure
This pressure difference promotes the movement of fluid into the posterior chamber.
What resists the movement of fluid into the posterior chamber?
Oncotic pressure of the plasma and aqueous humor
Oncotic pressure creates a barrier against fluid movement into the posterior chamber.
Accommodation is primarily controlled by which system?
Parasympathetic system
Which 2 enzymes help with production of aqueous humor?
Sodium potassium ATPase and carbonic anhydrase
* sodium transport is the primary set up because it sets up an osmotic gradient, and water follows the sodium ions
*these two enzymes are abundant in the non-pigmented layer of the ciliary epithelium
What are tropic hormones?
Affect other endocrine glands
Examples:
- FSH
- LH
- thyrotropin
- Adrenocorticotropic hormone
What are non-tropic hormones?
Do not affect endocrine glands
*examples:
- prolactin (affects mammary glands, secrete milk from breast, not an endocrine gland)
- somatropin (growth hormone,affects bones and muscles)
