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Physiology > Lecture #3 > Flashcards

Lecture #3 Flashcards

1
Q

Vision (sight)

A

perception of objects in the environment by means of light they emit or reflect

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2
Q

Light =

A

visible electromagnetic radiation
Human vision: wavelengths 400 - 700 nm
UV radiation: < 400 nm; too much energy
Infrared radiation: > 700 nm; too little energy

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3
Q

Anatomy of the Eye

A
  1. Three layers (tunics) that form the wall of the eyeball
  2. Optical components admit and focus light
  3. Neural component:
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4
Q

Fundus of the eye

A

Macula lutea -fovea centralis
• Pit in center
• Produces most finely detailed images

Optic disc
No photoreceptor cells
• If image falls on this area cannot be seen = blind spot

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5
Q

Iris diameter controlled by contractile elements

A

Parasympathetic - narrows pupil

Sympathetic - widens pupil

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6
Q

Pupillary constriction and dilation occurs:

A
  1. When light intensity changes

2. When gaze shifts between distant and nearby objects

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7
Q

Photopupillary reflex

A

pupillary constriction in response to light

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8
Q

Emmetropia

A

normal eyesight fixed on an object >6m away

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9
Q

hyperopia

A

farsighted – cannot see nearby

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10
Q

Myopia

A

(nearsighted) – Cannot see distance

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11
Q

Sensory Transduction

A

Retina converts light energy into action potentials

Rods,cones,and certain ganglion cells

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12
Q

Photoreceptor cells

A

absorb light and generate a chemical or electrical signal

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13
Q

Rod (photoreceptor) Cells

A

night vision or monochromatic vision

rhodopsin + cannot distinguish colour

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14
Q

Cone (photoreceptor) Cells

A

day or colour (trichromatic) vision

Photospin + can absorb colour

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15
Q

Outer Segment (photoreceptor cell)

A

Specialized to absorb light

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16
Q

Dark

Light

A

In DARK, rods steadily release the glutamate = DARK CURRENT

Rods absorb LIGHT 􏰀 stops glutamate

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17
Q

Principal Mechanisms of communication between cells

A
  1. Gap Junctions
  2. Neurotransmitter
  3. Paracrine - secreted into tissures
  4. Hormones - chemical messengers travel in bloodstream
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18
Q

Endocrine system

A

glands, tissues, and cells that secrete hormones

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19
Q

Endocrinology

A

organs that are traditional sources of hormones

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20
Q

Hormones

A

chemical messengers that are transported by the bloodstream

21
Q

Target organs or cells

A

those organs or cells that have receptors for a hormone and can respond to it

22
Q

Peptide Hormones

A
  • hydrophilic
  • cannot penetrate target cell
  • bind to surface receptors and activate IC processed
23
Q

Steroid Hormones

A
  • Hydrophobic
  • penetrates plasma membrane and bind to internal receptors
  • influence gene expression
    takes several hours or days
24
Q

Hormone Interactions

A

most are sensitive to >1 hormone = interactive effects

25
Q

Synergistic Effects

A

Multiple hormones act

together for greater effect

26
Q

Permissive effects

A

One hormone enhances the

target organ’s response to a second later hormone

27
Q

Antagonistic effects

A

One hormone opposes the

action of another

28
Q

Hypothalamus

A

forms floor and walls of third ventricle of brain

regulates primitive functions, but many are carried out by pituitary gland

29
Q

Hypothalamic Hormones

A

there are 8 hormones produced in the hypothalamus
6 inhibit the anterior pituitary

2 are released into capillaries in the posterior pituitary

30
Q

Posterior Pituitary Hormones

A
  • nerve tissue not a true gland example oxytocin and ADH
31
Q

Negative Feedback

A

increase target organ hormone levels which inhibits the release hypothalamic and/ or pituitary hormones

32
Q

Growth Hormone

A
  • many effects on the body

- liver produces insulin-like growth factors

33
Q

Hyper-secretion

A

Gigantism

34
Q

Hypo-secretion

A

Pituitary Dwarfism

35
Q

Thyroid Gland

A

largest endocrine gland
has 2 lobes
secretes T4, T3 in response to TSH
Secrete calcitonin

36
Q

Thyroid Disorders

A

Decreased TH at birth (congenital hypothyroidism)

Decreased Th at adult
(Myxedema)

Goiter - enlarged thyroid gland

37
Q

The Adrenal Medulla

A
  • secretes norepinephrine and epinephrine

- increases alertness and prepares the body for physical activity

38
Q

Mineralocorticoids

A

regulates electrocyte balance

stimulates Na and K

39
Q

Glucocorticoids

A

Regulates metabolism, helps the body adapt to stressors

secretes in response to ACTH

40
Q

Sex Steroids

A

Androgens: male development

41
Q

Adrenal Disorders

A

Cushing syndrome - excess cortisol secretion, lots of fat

Adrenogenital syndrome (AGS) 
enlargement of sexual organs, maculating effects on women
42
Q

The Pancreatic Islets

A

1-2 million islets - clusters of endocrine cells that secrete hormones that regulate glycemia (blood sugar)

43
Q

Glucagon

A

secreted by alpha a cells
released between meals b/c of falling blood glucose
In liver: stimulates release of glucose
Adipose tissue: stimulates the release of fatty acids

44
Q

Insulin

A

secreted by Beta cells
released after a meal when blood glucose is raising
stimulates cells to absorb nutrients, store and metabolize

45
Q

Diabetes Mellitus

A

Most prevalent metabolic disease in the world

• Disruption of metabolism due to hyposecretion or inaction

46
Q

Diabetes Pathogenesis

A

cells cannot absorb glucose
fat catabolism increases free fatty acids and ketones in the blood
chronic hyperglycemia

47
Q

Type 1 Diabetes Mellitus

A

5-10% of cases
insulin insufficiency
inherited

48
Q

Type 2 Diabetes Mellitus

A

90-95%
insulin resistance aka failure to respond to insulin

risk factors
heredity, age, obesity, ethnicity

Physiology (9 decks)

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