Chapter 15-17 Flashcards
What is the iris?
The colored part of the eye
What does the iris do?
Controls the size of the pupil
What is the pupil?
- central opening that regulates the amount of light entering the eye
Close vision and bright light
- pupils constrict
Distant vision and dim light
- pupils dilate
What is the term for farsightedness?
Hyperopia
Why can corneas be transplanted without fear of rejection?
- The cornea is avascular
- there are no antigens or antibodies for the recipients body to reject
Why does motion sickness occur?
- Sensory input mismatches
- Visual input differs from equilibrium input
- Conflicting information causes motion sickness
What special sense is not fully functional at birth?
Vision
What is the blind spot
- Optic disc (blind spot)
- The site where the optic nerve leaves the eye
- Lacks photoreceptors
What is the path of light through the eye?
- cornea
- aqueous humor
- lens
- vitreous humor
- entire neural layer of retina
- photoreceptors
What percentage of your sensory receptors are located in the eye?
70%
Define hormones
long-distance chemical signals; travel in blood or lymph
What is the “master endocrine gland?”
pituitary gland
What endocrine organ important in the immunity of a child?
Thymus
How do steroid hormones work?
- Diffuse into target cells and bind to intracellular receptors
- Receptor-hormone complex enters nucleus; binds to the specific region of DNA
- Prompts DNA transcription to produce mRNA
- mRNA directs protein synthesis
- Promote metabolic activities, or promote synthesis of structural proteins or proteins for export from the cell
Define up-regulation
target cells form more receptors in response to low hormone levels
What is the normal pH range for blood?
7.35-7.45
What is the parent cell for all formed elements in blood?
Hematopoietic stem cells (Hemocytoblasts)
What is the function of platelets?
Form temporary platelet plug that helps seal breaks in blood vessels
What organ regulates erythrocyte production
Kidney
