3. Receptors Rods – sense low levels of light Cones – sense higher level blue, green & red light...
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Transcript of 3. Receptors Rods – sense low levels of light Cones – sense higher level blue, green & red light...
3. Receptors
• Rods – sense low levels of light
• Cones – sense higher level blue, green & red light
Fig. 10.36
3. Receptors
• Rods – sense low levels of light
Fig. 10.40
• Cones – sense higher level blue, green & red light
3. Receptors
• Rods – sense low levels of light
Fig. 10.36
• Cones – sense higher level blue, green & red light C. Receptor transduction
1. Rhodopsin
3. Receptors
• Rods – sense low levels of light
• Cones – sense higher level blue, green & red light C. Receptor transduction
1. Rhodopsin
• Retinene (photopigment) + opsin (protein)
Fig. 10.37
2. Light
• Retinene – cis trans configuration
C. Receptor transduction
1. Rhodopsin
• Retinene (photopigment) + opsin (protein)
Fig. 10.37
2. Light
• Retinene – cis trans configuration
C. Receptor transduction
1. Rhodopsin
• Retinene (photopigment) + opsin (protein)
Fig. 10.37
2. Light
• Retinene – cis trans configuration
3. trans Retinene
• Activates g-protein (transducin) cascade
• Closes Na+ channels
• Hyperpolarizes cell
3. trans Retinene
• Activates g-protein (transducin) cascade
• Closes Na+ channels
• Hyperpolarizes cell
Fig. 10.37
3. trans Retinene
• Activates g-protein (transducin) cascade
• Closes Na+ channels
• Hyperpolarizes cell
D. Dark vs. light
• Photoreceptors depolarized and inhibitory
1. Dark
• Inhibit adjacent cells in retina
D. Dark vs. light
• Photoreceptors depolarized and inhibitory
1. Dark
• Inhibit adjacent cells in retina
Fig. 10.39
2. Light
• Photoreceptors inhibitory and depolarized
1. Dark
• Inhibit adjacent cells in retina
2. Light
• Receptors hyperpolarized (inhibited)
Fig. 10.39
• Photoreceptors inhibitory and depolarized
1. Dark
• Inhibit adjacent cells in retina
2. Light
• Receptors hyperpolarized (inhibited)
• Light is sensed
E. Dark adaptation
1. Light
• Receptors “bleached” rhodopsin in receptors
2. Dark
• 1st 5 minutes – rhodopsin in cones
• ~ 20 minutes – max sensitivity
E. Dark adaptation
1. Light
• Receptors “bleached” rhodopsin in receptors
2. Dark
• 1st 5 minutes – rhodopsin in cones
• ~ 20 minutes – max. sensitivity
• Due to rhodopsin in rods
• Light sensitivity by 100,000x
Chapter 11 – Endocrine
Endocrine glands – secrete into blood
Chapter 11 – Endocrine
I. General info.
A. Classifications
Endocrine glands – secrete into blood
Fig. 11.1
Chapter 11 – Endocrine
I. General info.
A. Classifications
Endocrine glands – secrete into blood
1. Amines – derived from single amino acids • Thyroid hormone Fig. 11.3
Fig. 9.9
• Epinephrine
I. General info.
A. Classifications
1. Amines – derived from single amino acids • Thyroid hormone
• Epinephrine
2. Polypeptides – chains of amino acids
• Antidiuretic hormone
disulfide bridges
• Insulin
I. General info.
A. Classifications
1. Amines – derived from single amino acids • Thyroid hormone
• Epinephrine
2. Polypeptides – chains of amino acids
• Antidiuretic hormone
• Insulin
3. Glycoproteins – carbohydrate + amino acids chains • Follicle stimulating hormone (FSH)
• Luteinizing hormone (LH)
4. Steroids – based on cholesterol (lipid)
3. Glycoproteins – carbohydrate + amino acids chains • Follicle stimulating hormone (FSH)
• Luteinizing hormone (LH)
4. Steroids – based on cholesterol (lipid)
• Progesterone
• Testosterone
• Cortisol
Fig. 11.2
3. Glycoproteins – carbohydrate + amino acids chains • Follicle stimulating hormone (FSH)
• Luteinizing hormone (LH)
4. Steroids – based on cholesterol (lipid)
• Progesterone
• Testosterone
• Cortisol
B. Pre- vs. Prohormones
1. Prohormones
• Peptide contained in longer peptide (e.g. opioids)
B. Pre- vs. Prohormones
1. Prohormones
• Peptide contained in longer peptide (e.g. opioids)
• Unessential peptide portions cleaved
• True of all peptide hormones
B. Pre- vs. Prohormones
1. Prohormones
• Peptide contained in longer peptide (e.g. opioids)
• Unessential peptide portions cleaved
• True of all peptide hormones
2. Prehormones
• Single molecule (e.g. thyroid hormone)
• Inactive until changed by target cell
Fig. 11.3
B. Pre- vs. Prohormones
1. Prohormones
• Peptide contained in longer peptide (e.g. opioids)
• Unessential peptide portions cleaved
• True of all peptide hormones
2. Prehormones
• Single molecule (e.g. thyroid hormone)
• Inactive until changed by target cell
C. Hormone common aspects
• Blood born
• Receptors on/in target cells
• Specific effect on target cell
C. Hormone common aspects
• Blood born
• Receptors on/in target cells
• Specific effect on target cell
• Can be turned off
D. Interactions
1. Synergistic
• e.g. – epinephrine & norepi. on heart
2. Permissive
• Additive or complementary
D. Interactions
1. Synergistic
• e.g. – epinephrine & norepi. on heart
2. Permissive
• Additive or complementary
• Hormone increases responsiveness of different hormone
• e.g. – cortisol allows epi. & norepi. to have catabolic effects
3. Priming effect
• Hormone presence increases sensitivity/effect of same hormone
2. Permissive
• Hormone increases responsiveness of different hormone
• e.g. – cortisol allows epi. & norepi. to have catabolic effects
3. Priming effect
• Hormone presence increases sensitivity/effect of same hormone
• e.g. – GnRH causes AP to be more sensitive to GnRH
4. Antagonistic
• Opposite effects
3. Priming effect
• Hormone presence increases sensitivity/effect of same hormone
• e.g. – GnRH causes AP to be more sensitive to GnRH
4. Antagonistic
• Opposite effects
• e.g. – Insulin ( glucose stores) & glucagon ( glucose stores)
E. Hormone levels
1. Half-life
• Time for metabolic clearance of half of hormone
E. Hormone levels
1. Half-life
• Time for metabolic clearance of half of hormone
2. Physiological levels
• Normal levels
3. Pharmacological levels
• Abnormally high levels
• Different physiological effects
4. Downregulation/desensitization
• Prolonged exposure sensitivity of target tissue
4. Downregulation/desensitization
• Prolonged exposure sensitivity of target tissue
II. Hormone mechanisms
A. Steroid hormones
1. Transport
• On carrier protein in blood
II. Hormone mechanisms
A. Steroid hormones
1. Transport
• On carrier protein in blood
• Passive diffusion through membrane
Fig. 11.4
A. Steroid hormones
1. Transport
• On carrier protein in blood
• Passive diffusion through membrane
Fig. 11.5
• Binds receptor in cytoplasm
2. Receptor
• Ligand binding domain – binds steroid
• DNA binding domain – binds DNA
3. Receptor-ligand complex
Fig. 11.5
2. Receptor
• Ligand binding domain – binds steroid
• DNA binding domain – binds DNA
3. Receptor-ligand complex
• Translocates to nucleus
Fig. 11.4
• Two complexes bind two receptor half sites on DNA (dimerization)
3. Receptor-ligand complex
• Translocates to nucleus
• Two complexes bind two receptor half sites on DNA (dimerization)
Fig. 11.4
Fig. 11.5
• Form homodimer
• Activate transcription
3. Receptor-ligand complex
• Translocates to nucleus
• Two complexes bind two receptor half sites on DNA (dimerization)
Fig. 11.5
• Form homodimer
• Activate transcription
4. On DNA
• Hormone response element recognized by complex
Fig. 11.5
• Form homodimer
• Activate transcription
4. On DNA
• Hormone response element recognized by complex
• 2 must bind (dimerization) for activity
B. Thyroid hormone
• T3 and T4
• Based on # of iodines
B. Thyroid hormone
• T3 and T4
• Based on # of iodines
Fig. 11.3
• T4 converted to T3 (active form) in cell
1. Transport
• Most carried on proteins in blood
B. Thyroid hormone
• T3 and T4
• Based on # of iodines
• T4 converted to T3 (active form) in cell
1. Transport
• Most carried on proteins in blood
• Passive diffusion into cell
• T4 converted to T3 (active form) in cell
1. Transport
• Most carried on proteins in blood
• Passive diffusion into cell Fig. 11.6
2. Receptor-ligand complex
• Formed in nucleus
• Complex forms heterodimer
Fig. 11.6
2. Receptor-ligand complex
• Formed in nucleus
• Complex forms heterodimer
• Other site bound by receptor-RXR (vit. A) complex
Fig. 11.7
• Transcription produces specific enzymes
2. Receptor-ligand complex
• Formed in nucleus
• Complex forms heterodimer
• Other site bound by receptor-RXR (vit. A) complex
• Transcription produces specific enzymes
C. 2nd messenger – adenylate cyclase
• Other site bound by receptor-RXR (vit. A) complex
• Transcription produces specific enzymes
C. 2nd messenger – adenylate cyclase
• Membrane receptor binding
Fig. 11.8
• Intracellular g-protein subunit dissociation
C. 2nd messenger – adenylate cyclase
• Membrane receptor binding
Fig. 11.8
• Intracellular g-protein subunit dissociation
• Subunit activates adenylate cyclase
• Forms cAMP from ATP
Fig. 11.8
• Intracellular g-protein subunit dissociation
• Subunit activates adenylate cyclase
• Forms cAMP from ATP
• cAMP activates protein kinase
Fig. 11.8
• Subunit activates adenylate cyclase
• Forms cAMP from ATP
• cAMP activates protein kinase
• Protein kinase phosphorylates (adds a phosphate) specific enzymes
Fig. 11.8
• Forms cAMP from ATP
• cAMP activates protein kinase
• Protein kinase phosphorylates (adds a phosphate) specific enzymes
• Enzymes activated or inhibited
• Forms cAMP from ATP
• cAMP activates protein kinase
• Protein kinase phosphorylates (adds a phosphate) specific enzymes
• Enzymes activated or inhibited
D. Phospholipase C-Ca++ second messenger
• Membrane receptor binding
• G-protein dissociates intracellularly
D. Phospholipase C-Ca++ second messenger
• Membrane receptor binding
• G-protein dissociates intracellularly
Fig. 11.9
• Activates phospholipase C (PLC)
• Releases inositol trisphosphate (IP3) from lipid
• IP3 releases Ca++ from endoplasmic reticulum
• Membrane receptor binding
• G-protein dissociates intracellularly
Fig. 11.9
• Activates phospholipase C (PLC)
• Releases inositol trisphosphate (IP3) from lipid
• IP3 releases Ca++ from endoplasmic reticulum
• Ca++ activates calmodulin
• Calmodulin has a variety of effects