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!!!

Detects sound frequency transmits signal to the auditory nerve

Vestibular canal Tympanic canal Cochlear duct Tectorial membrane Hair cells Axons of sensory neurons

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. Amplitude larger 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 balance and body position/orientation

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 Organisms Lateral 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 System Water 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 downward b. Once reach bottom of chamber, stimulating cilia of receptor cells c. 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 categories Endocrine cells may be organized into glands

Neurotransmitters Introduction to chemical signals in animals – Major categories

Neuroendocrine pathway Neuroendocrine signal Endocrine pathwayNeuroendocrine-to-endocrine pathway Neuroendocrine signal Endocrine signal Endocrine signal Endocrine cell Effector cell Response Stimulus Feedback inhibition Sensor cell Effector cell Feedback inhibition Neural signal CNS Stimulus Sensor cell Neural signal CNS Response Effector cell Endocrine cell Endocrine systems are regulated by negative feedback

Figure Hypothalamus Growth-hormone-releasing hormone: stimulates release of GH from pituitary gland Corticotropin-releasing hormone (CRH): stimulates release of ACTH from pituitary gland Gonadotropin-releasing hormone: stimulates release of FSH and LH from pituitary gland Thyroid-releasing hormone: stimulates release of TSH from thyroid gland Antidiuretic hormone (ADH): promotes reabsorption of H 2 O by kidneys Oxytocin: induces labor and milk release from mammary glands in females Steroids Polypeptides Amino acid derivatives

Figure Adrenal glands Thyroid gland Thyroxine: increases metabolic rate and heart rate; promotes growth Kidneys Epinephrine: produces many effects related to short-term stress response Aldosterone: increases reabsorption of Na + by kidneys Cortisol: produces many effects related to short-term and long-term stress responses Vitamin D: decreases blood Ca 2+ Testes (in males) Erythropoietin (EPO): increases synthesis of red blood cells Testosterone: regulates development and maintenance of secondary sex characteristics in males; other effects Steroids Polypeptides Amino acid derivatives

Figure Pituitary gland Thyroid-stimulating hormone (TSH): stimulates thyroid gland to secrete thyroxine Prolactin: stimulates mammary gland growth and milk production in females Follicle-stimulating hormone (FSH) and luteinizing hormone (LH): involved in production of sex hormones; regulate menstrual cycle in females Growth hormone (GH): stimulates growth Adrenocorticotropic hormone (ACTH): stimulates adrenal glands to secrete glucocorticoids Steroids Polypeptides Amino acid derivatives

Figure Parathyroid glands Pancreas (islets of Langerhans) Ovaries (in females) Insulin: decreases blood glucose Glucagon: increases blood glucose Estradiol: regulates development and maintenance of secondary sex characteristics in females; other effects Progesterone: prepares uterus for pregnancy Parathyroid hormone (PTH): increases blood Ca 2+ Steroids Polypeptides Amino acid derivatives

Steroids Cortisol Epinephrine Amino Acid Derivatives Receptor Secretin Peptides and Polypeptides Receptor Target cell Most not lipid soluble; bind to receptors on surface of target cell Not lipid soluble; bind to receptors on surface of target cell Lipid soluble; bind to receptors inside target cell Chemical characteristics of hormones – major classes

Hormone Transport and Action on Target

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 transduction pathway. This can affect the properties of enzymes/proteins, etc. or it may affect gene expression.

This picture shows a hormone traveling through the cell membrane and binding with a transcription factor. Which of the following statements are true? A) This is a membrane soluble (hydrophobic) hormone that alters gene transcription. B) This is a membrane soluble (hydrophobic) hormone that alters immediate enzyme activity and cell processes. C) This is a membrane insoluble (hydrophilic) hormone that alters gene transcription. D) This is a membrane insoluble (hydrophilic) hormone that alters 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