Lecture 16: Hypothalamus, Pituitary Gland, and Pineal Gland Flashcards
1
Q
What is unique about the Hypothalamus, Pituitary Gland and Pineal gland?
A
All of the structures are midline and there is only one of each
2
Q
What is the main function of the hypothalamus?
A
To maintain homeostasis
3
Q
How does the hypothalamus maintain homeostasis?
A
By regulating ANS (ascending and descending tract)
4
Q
What do the ANS ascending and descending tracts regulated by the hypothalamus do?
A
Control body temperature, hunger, thirst, fatigue, sleep and circadian cycles
5
Q
What does the hypothalamus link togehter?
A
The nervous system to the endocrine system
6
Q
What links the nervous system to the endocrine system?
A
The hypothalamus
7
Q
Through what does the hypothalamus link the nervous system to the endocrine system?
A
Via the pituitary gland
8
Q
How does the hypothalamus link the nervous and endocrine system via the pituitary gland?
A
By secreting neurohormones that stimulate or inhibit secretions of the pituitary gland
9
Q
What does the hypothalamus synthesize and secrete?
A
Neurohormones
10
Q
What are the five main categories of inputs to the hypothalamus?
A
- Nucleus of the solitary tract
- Reticular formation
- Retina
- Amygdala, hippocampus and the olfactory cortex
- Intrinsic hypothalamic receptors
11
Q
What kind of inputs does the nucleus of the solitary tract send to the hypothalamus?
A
Visceral sensory information from the glossopharyngeal nerve (blood pressure) and vagus information (gut distension?
12
Q
Where does the hypothalamus receive: Visceral sensory information from the glossopharyngeal nerve (blood pressure) and vagus information (gut distension) from?
A
The nucleus of the solitary tract
13
Q
What kind of inputs does the reticular formation send to the hypothalamus?
A
Inputs from the spinal cord including information about skin temperature which is relayed to the hypothalamus
14
Q
What kind of inputs does the Retina send to the Hypothalamus?
A
Some fibers from the optic nerve go directly to the suprachiasmatic nucleus to regulate circadian rhythm
15
Q
Where does the hypothalamus receive Inputs from the spinal cord including information about skin temperature which is relayed to the hypothalamus?
A
The Reticular formation
16
Q
Where does the hypothalamus receive information about light/dark to regulate circadian rhythms?
A
The retina
17
Q
What kinds of inputs do the Amygdala, hippocampus and the olfactory cortex send to the hypothalamus?
A
Inputs that help to regulate behaviours such as eating and reproduction
18
Q
Where does the hypothalamus receive inputs to control behaviour like eating and reproduction?
A
The amygdala, hypothalamus and olfactory cortex
19
Q
What do the intrinsic receptors of the hypothalamus regulate?
A
Thermoreceptors, osmoreceptors that measure temperature and ionic balance
20
Q
How can the hypothalamus be involved in HR regulation?
A
- The NTS can sample blood oxygen and co2 concentration from the heart and send this information to the hypothalamus
- In response the hypothalamus can send outputs via the DMNV to alter heart rate
21
Q
Where do autonomic afferents project back to and for what?
A
The hypothalamus instead of the thalamus for regular senssation
22
Q
What projects back to the hypothalamus instead of the thalamus?
A
Autonomic afferents
23
Q
What happens after autonomic afferent project back to the hypothalamus instead of the thalamus?
A
The hypothalamus then projects outward and has an effect that is not under conscious control
24
Q
What are the two main nuclei of the hypothalamic limbic system?
A
- Lateral Hypothalamic nuclei
- Ventromedial nucleus
25
What are the lateral hypothalamic nuclei and the ventromedial nuclei apart of?
The Hypothalamic limbic system
26
What is the Lateral hypothalamic nuclei transversed by?
Longitudinally by many fibres including the medial forebrain bundle
27
What does the medial forebrain bundle traverse?
The lateral hypothalamic nuclei
28
What is lateral hypothalamic area important for?
The control of food and fluid intake (desire to eat)
29
What controls the desire to eat?
The lateral hypothalamic nuclei
30
What do lesions to the hypothalamic nuclei cause?
Aphagia and adipsia
31
What is the ventromedial nucleus involved in?
The control of food and fluid intake
32
What controls the desire to stop eating?
The ventromedial nucleus
33
What do lesions to the ventromedial nucleus cause?
Abnormally increased food intake
34
What are the three main hypothalamic efferents?
- Pituitary gland
- Autonomic nervous system
- Limbic system
35
What is the endocrine section of the hypothalamic efferents?
The pituitary gland
36
What is the autonomic nervous system portion of hypothalamic efferents?
The vagus nerve
37
What structures are part of the limbic system hypothalamic efferents?
The amygdala and the hippocampus
38
How does the hypothalamus use the pituitary as an efferent?
The hypothalamus has control over hormone production (anterior lobe) or hormone release (posterior lobe) of the pituitary gland
39
What does the hypothalamus use the autonomic nervous system for as an efferent?
To control internal organs
40
What does the hypothalamus use the limbic system for in terms of efferents?
The hypothalamus initiates appropriate instinctual motor behavior repertoires (such as feeding)
41
What unites at the hypothalamus?
The autonomic and endocrine systems
42
What are the superior structures of the brain?
The cerebrum, thalamus and hypothalamus
43
What are the lower structures of the brain?
Midbrain, pons and cerebellum
44
What is the middle strucutres of the brain?
The hypothalamus which projects to the pituitary
45
What are the two parts of the pituitary?
The Adenohypophysis (anterior)
The Neurohypophysis (posterior)
46
What kind of gland is the pituitary?
An endocrine gland or a neuroendocrine gland
47
What is the hormone producing part of the pituitary?
The Adenohypophysis
48
What is the hormone releasing part if the pituitary?
The neurohypophysis
49
What is the Median eminence?
The projection of the hypothalamus to the posterior pituitary
50
What is the infundibulum?
The connection of the pituitary to the hypothalamus
51
What is the pituitary protected by?
Bone and surrounded by the hypophyseal fossa
52
What does the hypophyseal fossa surround?
The pituitary gland
53
What hormones are released by the anterior pituitary?
- TSH
- ACTH
- FSH and LH
- Growth Hormone (GH)
- Prolactin (PRL)
- Endorphins
54
What part of the pituitary releases:
- TSH
- ACTH
- FSH and LH
- Growth Hormone (GH)
- Prolactin (PRL)
- Endorphins
The anterior pituitary
55
What does the posterior pituitary release?
- Oxytocin
- ADH
56
What part of the pituitary releases oxytocin and ADH?
The posterior pituitary
57
What are the two nuclei of the medial hypothalamus?
- Paraventricular nucleus (PVN)
- Supraoptic nucleus (SON)
58
What does the Paraventricular nucleus do?
Synthesized Oxytocin and releases it in the posterior pituitary
59
What nucleus in the hypothalamus synthesizes oxytocin?
The Paraventricular nucleus
60
What is activation of the paraventricular nucleus cuased by?
The release of hormones induced by suckling
61
What does oxytocin do in females?
Stimulates milk production by the mammary gland and causes contraction of uterine muscle
62
What stimulates milk production by the mammary gland and causes contraction of the uterine muscle?
Oxytocin from the paraventricular nucleus
63
What is the breakdown of the meaning of oxytocin?
oxy = swift; tocin = birth
64
What does oxytocin do in males?
Causes smooth muscle contractions in the prostate
65
What causes smooth muscle contractions in the prostate?
Oxytocin
66
What does the Supraoptic nucleus do?
Produces antidiuretic hormone and releases it in the posterior pituitary
67
Where is antidiuretic hormone produced?
In the Supraoptic nucleus
68
When is antidiuretic hormone released?
During an increase in osmolarity
69
Where is the increase in osmolarity that causes antidiuretic hormone to be released sensed?
In osmosensitive neurons in the supraoptic nucleus
70
What is antidiuretic hormone (ADH) released in response to?
A rise in electrolytes of fall in blood pressure of blood volume
71
What does Antidiuretic hormone do?
- It acts on the kidneys to increase water absorption to maintain water homeostasis
- Causes constriction of the peripheral blood vessels to increase blood pressure
72
What can the release of ADH be inhibited by?
Coffee or alcohol
73
What happens if the release of ADH is inhibited by coffee or alcohol?
Water will not be reabsorbed and body will produce dilute urine
74
How will a lesion to the medial hypothalamus affect ADH?
It will affect the production of ADH
75
What would happen if ADH is not produced?
A person will be thirsty because they are continuously losing liquid in the urine
76
What will happen if too much ADH is produced?
A person will drink too much and suffer from water intoxication causing electrolytes in the blood to be diluted
77
What is important about the production of Oxytocin and ADH?
Both oxytocin and ADH are produced by the hypothalamus and carries them to the posterior pituitary
78
How are Oxytocin and ADH brought from the hypothalamus to the posterior pituitary?
They are brought in granules through the Hypothalamo-hypophyseal tract
79
What does the hypothalamo-hypophyseal tract do?
Carries oxytocin and ADH produced by the hypothalamus to the posterior pituitary
80
What do the Supraoptic nuclei and paraventricular nuclei do?
Manufacture ADH and oxytocin released by synaptic terminals at capillaries in the posterior lobe of the pituitary gland
81
What is the Hypophyseal portal system?
- The capillary networks in the median eminence are supplied by the hypophyseal artery
- Before leaving the hypothalamus, the capillary networks unite to form a series of larger vessels that spiral around the infundibulum to reach the anterior lobe
- Arterial blood from the hypothalamus area drain into the anterior pituitary to stimulate the anterior pituitary to produce hormones
82
How does the hypothalamus have a relationship with the anterior pituitary?
Through the portal system
83
What is the orchestrator of the endocrine system?
The anterior pituitary
84
What does thyroid stimulating hormone released by the anterior pituitary do?
Stimulates the activity of the thyroid
85
What does Adrenocorticotropin hormone released by the thyroid do?
Stimulates the activity of the adrenals
86
What does follicle stimulating hormone released by the anterior pituitary do?
Regulate gonadal function and reproductive cycle
87
What does Lutenizing hormone released by the anterior pituitary do?
Regulate gonadal function and reproductive cycle
88
What does Prolactin released by the anterior pituitary do?
Stimulate lactation and development of mammary glands
89
What do endorphins released by the anterior pituitary do?
Control of pain and nociceptive signals
90
How does Cortisol affect blood sugar?
It raised blood sugar by preventing insulin function and promoting gluconeogenesis
91
What is cushing syndrome?
Too much cortisol production
92
What disease is characterized by too much cortisol production?
Cushing's disease
93
What can tumors to the hypothalamus and pituitary glands do?
Lead to underproduction or overproduction of circulating hormones
94
What are the disorders of growth?
Dwarfism, gigantism and acromegaly
95
What are the disorders of sexual function?
Precocious puberty and hypogonadism
96
What are disorders of body water control?
Diabetes insipidus and pathological drinking
97
What is diabetes insipidus?
Losing to much water
98
What is pathological drinking?
Drinking too much water
99
What are disorders of eating?
Obesity and bulimia
100
What are disorders of adrenal cortical control?
Cushing's disease and adrenal insufficiency
101
How does the hypothalamus affect growth hormone?
The hypothalamus maintains homeostatic levels of GH
102
How does GH affect cells?
Cells under the action of GH increase in size (hypertrophy) and number (hyperplasia)
103
How does GH affect bones?
GH causes an increase in bone length and thickness by deposition of cartilage at the ends of bones
104
How do sex hormones affect bones?
During adolescence, sex hormones cause replacement of cartilage by bone, halting further bone growth even though GH is still present
105
What can too little growth hormone cause?
Gigantism
106
What can too little GH cause?
Dwarfism
107
What is Gigantism?
Excess GH before puberty
108
What causes dwarfism?
hGH deficiency before puberty
109
What causes Acromegaly?
Excess hGH after puberty
110
What is the difference between Gigantism and Acromegaly?
- Gigantism is when there is excess growth hormone before puberty
- Acromegaly is when there is excess growth hormone after puberty
111
What happens in gigantism?
Excess hGH before puberty causes excessive length of bones, coarsening of the facial bone, slowed sexual development and mental slowness
112
What happens in acromegaly?
Excess hGH after puberty causes thickening and coarsening of bones, enlargement of lips, nose, jaw and thickening of tongue of skin. Bones also thicken
113
What vision loss can a pituitary tumor cost?
Bitemporal hemianopsia
114
How can a pituitary tumor cause bitemporal hemianopsia?
It can compress the optic chiasm
115
How does bitemporal hemianopsia affect the visual field?
It causes tunnel vision. So you are unable to see the peripheral visual fields
116
What is the mechanism behind bitemporal hemianopsia?
The axons from the midline that see the peripheral visual fields usually cross over at the optic chiasm, but because it is compressed people are no longer able to see
117
What is the Transsphenoidal approach to removing pituitary tumors?
Entering through the nasal cavity and drilling through the sella turcica
118
What is the Epiphysis?
The pineal gland
119
What is another name for the pineal gland?
The epyphsis
120
What does the Pineal gland sit in close proximity to?
The aqueduct of the 3rd and 4th ventricle
121
What is the main function of the Pineal Gland?
To produce melatonin in the absence of light stimulation
122
What nuclei do retinal axons project to?
The suprachiasmatic nuclei (SCN) of the hypothalamus
123
What is the Retinohypothalamic tract?
The pathway that the retinal axons project to the suprachiasmatic nuclei when there is light stimulation
124
What happens after light stimulates the retina and it travels to the SCN?
Nerve impulses originate from the SCN via the sympathetic nervous system and travel to the pineal gland to inhibit the production of melatonin
125
How is the production of melatonin inhibited in the pineal gland?
Retinal axons sense light and project to the suprachiasmatic nucleus. The suprachiasmatic nucleus then sends nerve impulses via the sympathetic nervous system which travels to the pineal gland to inhibit melatonin production
126
When do impulses from the SCN on the pineal gland stop?
At night when there is no light to stimulate the hypothalamus
127
What does the SCN do in terms of circadian rhythms?
It serves as a clock that regulates brain and endocrine systems
128
What are the Circadian Rhythms controlled by?
Endogenously: Clock genes
Exogenously: Light regulation and environment
