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April 22, 2014 – Hearing and equilibrium II Review of the mechanics of hearing . Maintaining e quilibrium in mammals. Equilibrium in other animals Sensory deprivation and hallucinations. Cell-to-cell signalling – Hormones!!!. - PowerPoint PPT Presentation
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April 22, 2014 – Hearing and equilibrium II
1. Review of the mechanics of hearing.2. Maintaining equilibrium in mammals.3. Equilibrium in other animals 4. Sensory deprivation and hallucinations. 5. Cell-to-cell signalling – Hormones!!!
• Two Components of Sound Wave:There are two main components of the sound wave
that are detected and used by the auditory system:1. Volume- Amplitude (height of
wave)
Hearing- Mammals (con’t)
2. Pitch- Frequency (no. of waves per unit time)
1. Amplitudelarger amplitude= louder sound
-larger amplitude results in stronger pressure on the hair cells, thereby causing more action potentials
(more neurotransmitters released)2. Pitch
- basilar membrane varies in thickness and flexibility-base= narrow and stiff; stimulated by higher pitch-tip (apex)= wider and more flexible; stimulated by
lower pitch
Hearing- Mammals (con’t)
Equilibrium- Mammals
Semicircular Canals
Organs to detect body position and maintain balance located in inner ear
1.) Utricle and Saccule (2 parts of same organ)-located next to oval window-detect which direction is up and detect body position and acceleration
2.) Semicircular Canals (3 canals in total)-next to utricle-detect angular movements
1. Utricle and saccule contain clusters of hair cells embedded in a gel called a cupula.
2. Cupula contains otoliths.
3. Cupula (with otoliths) is heavier than the endolymph (fluid) in the utricle and saccule, so gravity is pulling the cupula down on to the hairs of the hair cells.
4. Changes in angle of body (i.e. changes in position of head) change the force on the hair cells.
- causes stimulation of some cells that weren’t stimulated before- causes some to increase/decrease their signals
Semicircular Canals
3 canals (“loops”) - one for each plane:- side-to-side- front and back- up and down
Same mechanism of stimulation as for utricle and saccule (cupula with otoliths, hair cells, etc.)
Equilibrium- Mammals
Semicircular Canals
Equilibrium- Aquatic OrganismsLateral Line System 1. Fish: lateral line on both sides of body
series of mechanoreceptors called neuromasts on body just under the epidermis
Small openings (pores) in epidermis allow for water to enter into lateral line canals
Lateral Line SystemWater stimulates clusters of hair cells in the neuromasts by bending the
cupula (gelatinous cap over the hair cells)
Stimulation causes release of neurotransmitters, sending signals through sensory nerves to brain
Equilibrium- Lateral Line (con’t)
Most invertebrates have sensory “organ” called statocysts
Parts of statocyst:-layer of ciliated receptor cells surrounding an open chamber-inside chamber are grains of dense material called statoliths
Equilibrium- Invertebrates
2. Pathway: a. Gravity causes statoliths to settle downwardb. Once reach bottom of chamber, stimulating cilia of receptor
cellsc. Stimulated cells release neurotransmitters, stimulating
connecting sensory nerve fibers
Sensory deprivation and hallucination• Degradation of vision and hearing is associated with visual and
auditory hallucinations.
• Thought to be associated with hyperactivity or visual and auditory brain regions that received degraded input from sensory organs.
• Distinctly different in character from drug-induced and psychotic hallucinations
• Charles Bonnett syndrome.
• Link to Oliver Sacks’ TED talk.
Introduction to chemical signals in animals – Major categoriesEndocrine cells may be organized into glands
Neuroendocrine pathway
Neuroendocrinesignal
Endocrine pathway Neuroendocrine-to-endocrine pathway
Neuroendocrinesignal
Endocrinesignal
Endocrinesignal
Endocrine cell
Effectorcell
Response
Response
Stimulus Stimulus
Feed
back
inhi
bitio
n
Feed
back
inhi
bitio
n Sensor cell
Effectorcell
Feed
back
inhi
bitio
n
Neural signal
CNS
Stimulus
Sensor cell
Neural signal
CNS
Response
Effectorcell
Endocrine cell
Endocrine systems are regulated by negative feedback
Figure 47-3-1Hypothalamus
Growth-hormone-releasing hormone:stimulates release of GH from pituitarygland
Corticotropin-releasing hormone (CRH):stimulates release of ACTH from pituitarygland
Gonadotropin-releasing hormone:stimulates release of FSH and LH from pituitary gland
Thyroid-releasing hormone: stimulatesrelease of TSH from thyroid gland
Antidiuretic hormone (ADH): promotesreabsorption of H2O by kidneys
Oxytocin: induces labor and milk releasefrom mammary glands in females
Steroids
PolypeptidesAmino acid derivatives
Figure 47-3-2
Adrenal glands
Thyroid gland
Thyroxine: increases metabolic rateand heart rate; promotes growth
Kidneys
Epinephrine: produces many effectsrelated to short-term stress response
Aldosterone: increases reabsorption ofNa+ by kidneys
Cortisol: produces many effects related toshort-term and long-term stress responses
Vitamin D: decreases blood Ca2+
Testes (in males)
Erythropoietin (EPO): increasessynthesis of red blood cells
Testosterone: regulates developmentand maintenance of secondary sexcharacteristics in males; other effects
Steroids
PolypeptidesAmino acid derivatives
Figure 47-3-3
Pituitary gland
Thyroid-stimulating hormone (TSH):stimulates thyroid gland to secretethyroxine
Prolactin: stimulates mammary glandgrowth and milk production in females
Follicle-stimulating hormone (FSH)and luteinizing hormone (LH): involvedin production of sex hormones;regulate menstrual cycle in females
Growth hormone (GH): stimulates growth
Adrenocorticotropic hormone (ACTH):stimulates adrenal glands to secreteglucocorticoids
Steroids
PolypeptidesAmino acid derivatives
Figure 47-3-4
Parathyroid glands
Pancreas (islets of Langerhans)
Ovaries (in females)
Insulin: decreases blood glucose
Glucagon: increases blood glucose
Estradiol: regulates development andmaintenance of secondary sexcharacteristics in females; other effectsProgesterone: prepares uterus for pregnancy
Parathyroid hormone (PTH): increases blood Ca2+
Steroids
PolypeptidesAmino acid derivatives
Steroids
CortisolEpinephrine
Amino AcidDerivatives
Receptor
Secretin
Peptides and Polypeptides
Receptor
Receptor
Target cell
Most not lipid soluble;bind to receptors onsurface of target cell
Not lipid soluble;bind to receptors onsurface of target cell
Lipid soluble;bind to receptorsinside target cell
Chemical characteristics of hormones – major classes
Hydrophobic messengers pass into cell (and sometimes the nucleus) where they bind with transcription factors which affect gene expression.
Hydrophilic hormones bind to a receptor on the cell membrane which causes several reactions known as a signal transductionpathway. This can affect the properties of enzymes/proteins, etc. or it may affect gene expression.
This picture shows a hormone traveling throughthe cell membrane and binding with a transcription factor.
Which of the following statements are true?
A) This is a membrane soluble (hydrophobic) hormone thatalters gene transcription.
B) This is a membrane soluble (hydrophobic) hormone thatalters immediate enzyme activity and cell processes.
C) This is a membrane insoluble (hydrophilic) hormone thatalters gene transcription.
D) This is a membrane insoluble (hydrophilic) hormone thatalters immediate enzyme activity and cell processes.
Barry Bonds was accused of using a steriod ‘the cream’ to increase his athletic performance. He supposedly applied this to his skin. What does this tell you about the nature of this hormone?
A. The hormone was membrane insoluble.B. The hormone was membrane soluble.C. The hormone initiated a signal transduction pathway.D. A and C