Endocrine system
Thursday, 7 October 2021 11:19 AM
Endo vs exocrine glands
- Endocrine
○ Secrete into blood vessels
§ Secretory vessels fuse with membrane and empty their
vessels
§ Could be a neuron that released content of vesicles into
blood vessels
○ No ducts
○ Uses circulatory system
- Exocrine
○ Secrete outside
○ Secrete into GI tract is also exocrine
○ Duct opens into outside
Major endocrine organs
- Pituitary gland - hypophysis
○ Location
§ Only one gland - no right / left
§ Located by identifying the mamillary bodies and optic
chiasm
□ Use to identify anterior and posterior aspect of
pituitary
§ Below hypothalamus
§ Suspended on tissue that connect hypothalamus and
pituitary gland
□ Stalk
§ Protected by sphenoid bone
□ Sella turcica
® Turkish saddle
® Indentation accommodating the gland
® Saddle like indentation on body of sphenoid
bone
○ Development
§ Originated from 2 sources
□ Dual embryological origin
® Epithelial
◊ Oropharynx ectoderm
◊ Forms anterior lobe
, ○ Development
§ Originated from 2 sources
□ Dual embryological origin
® Epithelial
◊ Oropharynx ectoderm
◊ Forms anterior lobe
® neural
◊ Extension of neuroectoderm
◊ Forms posterior lobe
□ Develops from oropharynx
® Oral cavity
§ 2 sources then fuse together to form gland in the sella
turcica of sphenoid
§ Anterior part
□ From oropharynx ectoderm
® Finger of ectoderm grows upwards from
mouth
◊ Protrusion is called Rathke's pouch
□ adenophysis
§ Posterior part
□ Neural ectoderm
® Finger of neuroectoderm protrudes ventrally
from diencephalon of developing brain
□ neurophysis
○ Morphology
§ Anterior aspect
□ Identify by optic chiasm
® Identify posterior with mammillary bodies
□ Hypothalamus extension produces posterior part
of pituitary gland
® Neurophysis
® Connect through the infundibulum
□ Anterior regions
® Pars tuberalis
◊ Surrounds infundibular stalk
® Pars intermedia
◊ Separated by pars distalis by
hypophyseal cleft
® Pars distalis
◊ Largest section
§ Posterior pituitary
□ Doesn’t produce hormones, but just stores and
secretes them
□ Infundibulum
□ Posterior lobe
® Neurohypophysis
Thursday, 7 October 2021 11:19 AM
Endo vs exocrine glands
- Endocrine
○ Secrete into blood vessels
§ Secretory vessels fuse with membrane and empty their
vessels
§ Could be a neuron that released content of vesicles into
blood vessels
○ No ducts
○ Uses circulatory system
- Exocrine
○ Secrete outside
○ Secrete into GI tract is also exocrine
○ Duct opens into outside
Major endocrine organs
- Pituitary gland - hypophysis
○ Location
§ Only one gland - no right / left
§ Located by identifying the mamillary bodies and optic
chiasm
□ Use to identify anterior and posterior aspect of
pituitary
§ Below hypothalamus
§ Suspended on tissue that connect hypothalamus and
pituitary gland
□ Stalk
§ Protected by sphenoid bone
□ Sella turcica
® Turkish saddle
® Indentation accommodating the gland
® Saddle like indentation on body of sphenoid
bone
○ Development
§ Originated from 2 sources
□ Dual embryological origin
® Epithelial
◊ Oropharynx ectoderm
◊ Forms anterior lobe
, ○ Development
§ Originated from 2 sources
□ Dual embryological origin
® Epithelial
◊ Oropharynx ectoderm
◊ Forms anterior lobe
® neural
◊ Extension of neuroectoderm
◊ Forms posterior lobe
□ Develops from oropharynx
® Oral cavity
§ 2 sources then fuse together to form gland in the sella
turcica of sphenoid
§ Anterior part
□ From oropharynx ectoderm
® Finger of ectoderm grows upwards from
mouth
◊ Protrusion is called Rathke's pouch
□ adenophysis
§ Posterior part
□ Neural ectoderm
® Finger of neuroectoderm protrudes ventrally
from diencephalon of developing brain
□ neurophysis
○ Morphology
§ Anterior aspect
□ Identify by optic chiasm
® Identify posterior with mammillary bodies
□ Hypothalamus extension produces posterior part
of pituitary gland
® Neurophysis
® Connect through the infundibulum
□ Anterior regions
® Pars tuberalis
◊ Surrounds infundibular stalk
® Pars intermedia
◊ Separated by pars distalis by
hypophyseal cleft
® Pars distalis
◊ Largest section
§ Posterior pituitary
□ Doesn’t produce hormones, but just stores and
secretes them
□ Infundibulum
□ Posterior lobe
® Neurohypophysis
