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Human Anatomy > Special senses and endocrine system lecture 11&12 > Flashcards

Special senses and endocrine system lecture 11&12 Flashcards

1
Q

special senses

A 
Taste, Smell, Hearing, Balance, Sight
special senses
– have specialised sensory cells
– are located in the head
– are innervated by cranial nerves
– have specialised associated anatomical structures
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2
Q

name the cranial nerves

A 
Olfactory 
Optic 
Oculomotor
Trochlear 
Trigeminal** 
Abducens
Facial 
Accoustic*
Glossopharyngeal 
Vagus 
Spinal accessory  
Hypoglossal
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3
Q

how to remember cranial nerves

A

on old olympus’ towering tops a Finn and German viewed some hops

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4
Q

how to remember cranial nerves’ functions

A

some say marry money but my brother says big brains matter more

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5
Q

taste

A

• Sensory cells: Gustatory cells (with supportive cells in taste bud)
• Nerve(s): Facial, Glossopharyngeal, Vagus
(NB because taste involves three different nerves, taste disorders are less common than smell disorders, since the system is less likely to be put completely out of business)
• Brain processing: Gustatory cortex

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6
Q

types of papillae

A 
Circumvallate or vallate papillae
• Large, round, least numerous (approx. 7-12)
Fungiform papillae
• Over entire tongue surface
• Mushroom shaped
Filiform papillae
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7
Q

taste buds

A

• Taste buds are found mainly on on the tops of fungiform papillae, and in the epithelium of the side walls of the foliate and circumvallate papillae
• Taste buds consist of 50-100 epithelial cells
– gustatory (taste) cells
– basal cells
• Taste buds are routinely burned by hot food, but are replaced every 7-10 days, by basal cells acting as stem cells

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8
Q

vagus nerve

A
  • Sensory and motor

* Taste receptors in epiglottis and lower pharynx

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9
Q

Glossopharyngeal nerve

A
  • Sensory and motor

* Taste receptors in posterior third of tongue and pharynx

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10
Q

facial nerve

A
  • Sensory and motor
  • Taste receptors in anterior two thirds of tongue
  • These afferent fibres synapse in the solitary nucleus of the medulla, and then to gustatory cortex via thalamic nucleus
  • As taste impulses pass through the solitary nucleus, they initiate parasympathetic responses associated with salivation and digestion
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11
Q

smell

A
  • Sensory cells: Olfactory cells (plus supporting cells in olfactory epithelium)
  • Nerve: Olfactory nerve (I)
  • Brain processing: Olfactory bulb
  • Note that the olfactory nerve has a single function, and it is the only nerve involved in that function; all of the processing occurs in one part of the brain
  • Contrast this with taste: three nerves, more than one function for these nerves
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12
Q

hearing

A
  • Sensory cells: Hair cells (in organ of Corti in cochlea)
  • Nerve: Auditory or vestibulocochlear (VIII)
  • Brain processing: Auditory cortex in temporal lobe
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13
Q

balance

A
  • Sensory cells: Hair cells (cupula of vestibules of semicircular canals)
  • Nerve: Auditory or vestibulocochlear (VIII)
  • Brain processing: Cerebellum
  • Note: one nerve, two functions (balance and hearing)
  • The auditory nerve picks up information relating to both hearing and balance and transmits it to two parts of the brain
  • Blows to the back of the head and therefore cerebellum can cause balance problems, and the appearance of drunkenness
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14
Q

sight

A
  • Sensory cells: Rods and cones in retina
  • Nerve: Optic (II)
  • Brain processing: Visual cortex in occipital lobe
  • Again, the nerve has a single function, and it is the only nerve involved in that function; all of the processing occurs in one part of the brain
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15
Q

Specificity of response- hormonal vs nervpus system

A
  • The nervous system targets organs precisely

* Hormones can have widespread effects (eg thyroid hormone, growth hormone)

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16
Q

Speed of response- hormonal vs nervous system

A
  • The nervous system (Lecture 9) typically responds to stimuli within milliseconds
  • The endocrine system can take from several seconds to several days to respond
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17
Q

Cessation of response- hormonal vs ns

A
  • When a stimulus stops, the nervous system stops responding almost immediately
  • Hormonal effects can last for several days, or longer
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18
Q

Persistence of response- hormonal vs ns

A
  • With repeated stimulation, neurons adapt and their response declines
  • The endocrine system is more persistent: eg, thyroid hormone levels increase in cold weather and remain high as long as it remains cold
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19
Q

Long distance chemical signalling

A

Hormones
• Produced by the endocrine system
• Travel throughout the body via the blood
• Eg insulin

20
Q

Local chemical signalling

A

Paracrines
• Affect cell types other than those releasing them
• Eg some pancreatic cells release somatostatin, inhibiting insulin release in a different population of pancreatic cells
Autocrines
• Exert effects on the same cells that secrete them
• Eg certain prostaglandins produced by smooth muscle cells cause those smooth muscle cells to contract

21
Q

endocrine system

A

• Endocrine glands (ductless glands) release
hormones into interstitial fluid (ultimately into
circulatory system)
• Exocrine glands secrete into ducts (salivary
glands are an example)
• Note similarity to nervous system in which
neurons release neurotransmitters

22
Q

Stimulation via the blood

A

Humoral stimulation
• Some hormones are released in direct response to changes in levels of ion or nutrients in blood
Hormonal stimulation
• Other hormones (eg hypothalamus releases hormones stimulating release of anterior pituitary hormones, which in turn stimulate other endocrine glands (eg thyroid, adrenal cortex, gonad))

23
Q

Stimulation via nerve fibres

A

Neural stimulation
• In a few instances, hormone release is stimulated by nerve fibres; eg sympathetic nervous system causes adrenal medulla to release norepinephrine and epinephrine

24
Q

Endocrine organs

A
  • Hypothalamus and pituitary glands
  • Pineal gland
  • Thyroid gland
  • Parathyroid glands
  • Adrenal glands
  • Pancreas
  • Thymus
  • Gonads
25
Q

Hypothalamus

A
  • Hypothalamus forms the floor and walls of third ventricle of brain
  • Hypothalamus regulates water balance, sex drive and many other functions via interactions with the pituitary gland (hypophysis)
26
Q

Pituitary

A

• Pituitary consists of two parts with separate developmental origins:
– adenohypophysis (anterior three quarters)
– neurohypophysis (posterior quarter)

27
Q

Neurohypophysis

A
  • Posterior pituitary
  • Not a true gland
  • Actually part of brain
  • Neural tissue
  • Releases neurohormones (ie hormones secreted by neurons)
28
Q

Adenohypophysis

A
  • Anterior pituitary
  • Glandular tissue
  • Releases hormones
29
Q

sphenoid

A

• Butterfly-shaped
• Keystone of cranium; articulates with all other cranial bones
• Central body with three paired processes:
– greater wings
– lesser wings
– pterygoid processes
• Superior surface bears sella turcica (‘Turk’s saddle’), in which sits hypophysis (pituitary)

30
Q

Anterior pituitary hormones

A
  • Human Growth Hormone (hGH)
  • Thyroid Stimulating Hormone (TSH) or thyrotropin
  • Follicle-stimulating Hormone (FSH)
  • Lutenizing Hormone (LH)
  • Prolactin (PRL)
  • Adrenocorticotropin (ACTH) or corticotropin
31
Q

Posterior pituitary hormones

A
  • Oxytocin (post-delivery hormone)

* Antidiuretic Hormone (ADH) or vassopressin

32
Q

pineal gland

A

• The pineal gland secretes melatonin at night (a monamine) from serotonin
• This fluctuates with seasonal changes in day length
• In animals with seasonal breeding, this
regulates reproductive state
• Function of pineal gland in humans is
obscure; it may be involved in circadian
rhythm and some mood disorders
• Melatonin levels are elevated in premenstrual syndrome and in seasonal affective disorder

33
Q

thyroid gland

A

• Located on trachea, just inferior to larynx
• Two lateral lobes connected by isthmus
• Largest pure endocrine gland in body
• Extremely well supplied with blood (superior and inferior thyroid arteries), so thyroid surgery is extremely complicated
• About 50% of people have an extra,
pyramidal lobe growing up from the isthmus
• Others lack an isthmus, or have thyroid
tissue in the root of the tongue or elsewhere in the neck
• Thyroxine, calcitonin

34
Q

parathyroid gland

A

• Tiny glands on posterior of thyroid
• Usually four, but may be up to eight, and
some may be located elsewhere in neck or
even thorax
• Produce parathyroid hormone (PTH, or parathormone), a protein hormone controlling
calcium levels in blood

35
Q

adrenal glands

A

• Located on top of kidneys
• Structurally and functionally, each adrenal gland comprises two endocrine glands, each
producing its own set of hormones:
– inner adrenal medulla (part of sympathetic nervous system)
– outer adrenal cortex (glandular tissue)

36
Q

Adrenal medullary hormones

A

• Catecholamines (epinephrine and norepinephrine; increase heart rate, blood pressure and BMR)

37
Q

Adrenal cortical hormones

A
  • Mineralcorticoids, including aldosterone (affects N a and K levels)
  • Glucocorticoids, including cortisol (regulates metabolism, resistance to stress)
  • Gonadocorticoids, including androgens (prepubertal growth, sex drive)
38
Q

cushing’s syndrome

A

• Caused by adrenal tumor or tumor that
stimulates adrenocorticotropic hormone (ACTH) causing overproduction of cortisol by adrenal cortex
• Symptoms include tendency to gain weight, acne, growth of facial hair
• Iatrogenic Cushing’s Syndrome can be
caused by taking steroids

39
Q

pancreas

A 
• Spongy gland located below and behind the stomach
• Critical in digestion
Secretes:
• Glucagon
– 29aa polypeptide; increases blood glucose
– 1 molecule of glucogen can release 100
million glucose molecules into blood)
• Insulin
– 51aa protein; decreases blood glucose
40
Q

thymus

A

• Part of both endocrine and lymphatic systems
• Located between heart and base of neck
• Firm and conical in children; red due to rich blood supply
• After age 15 or so, contains less lymphatic
tissue and shrinks; becomes yellowish as it accumulates fat
• By old age, difficult to distinguish from
surrounding fat
• Site of maturation of T lymphocytes
• Hormones that promote T-cell proliferation
(involved in immune system)

41
Q

ovaries

A

• Oestrogens
– Maturation of reproductive organs
– Appearance of secondary sex characteristics at puberty
• Progesterone
– breast development, control of menstrual
cycle (in combination with oestrogens)
• Also inhibin and relaxin

42
Q

testes

A 
• Testosterone
– maturation of reproductive organs
– secondary sex characteristics
– sex drive
– sperm production
• Inhibin
– inhibits FSH production
43
Q

heart

A
  • High blood pressure stretches heart wall, stimulating atrial muscle to produce atrial natriuretic peptide (ANP)
  • ANP increases urine output and sodium excretion, and inhibits angiotensin II: this lowers blood pressure
44
Q

kidneys

A
  • Renin: converts angiotensin to angiotensin I

* Convert calcidiol to calcitriol (vitamin D3)

45
Q

stomach and small intestine

A
  • Many enteric hormones, eg gastrin

* Other tissues and organs with endocrine cells include the skin, adipose tissue and the placenta

46
Q

liver

A

• Angiotensin: converted by kidneys, lungs and other organs to angiotensin II, which
regulates blood pressure)
• Calcidiol
• Hepcidin: role in iron homeostasis
• Insulin-like growth factor (IGF): mediates
growth hormone action
• Erythropoietin (EPO): stimulates red blood
cell production

Human Anatomy (12 decks)

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