BIO 2301 Human Physiology - Exam 1 CSCC - SU18

BIO 2301 Human Physiology - Exam 1 (CSCC - SU18) Actual / 181 Questions And 100% Verified CORRECT Answers

Homeostasis The body's ability to maintain internal stability, even in the face of external change

Components of a homeostatic mechanism

- Control center: usually found in the hypothalamus of the

brain, contains the "set point" for the variable, receives info from the receptors and sends instructions to effectors

- Receptors: detect or sense the variable and send that info to

the control center

- Effectors: receive instructions from the control center and

carry them out to get the variable back to normal

Examples of homeostatic mechanisms

• The maintenance of body temperature
• Blood glucose levels
• Blood sodium levels
• Blood pressure

• / 4

Negative feedback

• When a change in the variable occurs, the body responds by

causing a change in the opposite direction

• The main way that homeostatic mechanisms work

What do the ossicles help do?Amplify sound

Organ of corti

• The receptor for hearing
• Found in the cochlear duct of the cochlea

Structure of the organ of corti

• Contains hair cells (stereocilia) that are embedded in the

tectorial membrane

• Sits on the basiliar membrane

Vibration of the cilia of the hair cells

• This will cause action potentials which will then travel up the

CN VIII to the brain where conscious perception (hearing) actually occurs

• / 4

What determines pitch discrimination?The basilar membrane

What determines amplitude discrimination?The number of hair cells stimulated

Conduction deficit

• Occurs when the sound vibrations cannot be conducted to

the inner ear along the normal conduction pathway

• Can be caused by fused ossicles, a ruptured eardrum,

increased wax pressing against the eardrum, etc.

• Treatments include hearing aids to amplify the sound and

send the vibrations through the bones to the inner eart

Nerve deficit

• Occurs when there is damage to the neurons in the inner ear
• No treatment although cochlear implants help some people

How can you distinguish between conduction deficits and nerve deficits? 3 / 4

By having a person hum to vibrate their skull - if they can hear it, then there is a conduction deficit and it will sound louder in the deaf ear; if they cannot hear it, it is nerve deficit

Vestibular function

• Also known as equilibrium or balance
• Controlled by the cerebellum of the brain

- The cerebellum receives info from: the eyes, the vestibular

apparatus (utricle, saccule, and ampulla of the semicircular canals), and the kinesthetic receptors (found in the joints - tell info on proprioception, where the limbs are in space)

• Balance can be maintained as long as the cerebellum gets

info from 2 out of 3 of those sites

Utricle and sccule

• Found in the vestibule of the inner ear
• Detect linear acceleration of the head or head tilt (moving

head up and down or back and forth)

Ampulla of the semicircular canals

• Found in the inner ear
• Detect rotation of the eat (shaking head, tipping head to

shoulder)

• / 4