Biology 127- Human Biology Lecture 14 Overview of Endocrine System Pituitary & Hypothalamus Thyroid Gland Pancreas Adrenal Glands
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Biology 127- Human Biology Lecture 14Overview of Endocrine System
Pituitary & Hypothalamus
Thyroid Gland
Pancreas
Adrenal Glands
Endocrine System-made of small glands.
Glands produce chemical- hormone
Overview of Endocrine System
Hormones- chemicals that are released into the bloodstream and travel to distant sites
Long-distance signaling
Endocrine cell Bloodvessel
Hormone travelsin bloodstreamto target cells
Targetcell
(c) Hormonal signaling
Overview of Endocrine System
Target Cells- Cells that are affected by hormone.
Hormones- function in five areas:1)Homeostasis2) Growth and development3) Reproduction4) Energy production, storage and use5) Behavior
Cells of body exposed to hormones 24 hours.
Overview of Endocrine System
Target Cells- are selective. Only respond to specific hormones.
Only target cells have the receptor to hormone.
Overview of Endocrine System
EXTRACELLULARFLUID
Plasma membrane
Receptor
Signalingmolecule
Reception1
Two types of hormones- Trophic and Nontrophic hormones.
Trophic Hormones- stimulate other endocrine glands to produce and secrete other hormones
Overview of Endocrine System
Nontrophic hormones- stimulate cellular growth, metabolism, and other functions.
Example- thyroxine
Overview of Endocrine System
Hormones can be classified based upon the type of molecule they are:
1) Steroids; 2) Proteins; 3) Amines
Overview of Endocrine System
Hormones production is controlled by negative feedback loops- the end product of a process inhibits its production
Overview of Endocrine System
Hormones production is controlled by positive feedback loops- the end product of a process stimulates its production
Overview of Endocrine System
Biology 127- Human Biology Lecture 14Overview of Endocrine System
Pituitary & Hypothalamus
Thyroid Gland
Pancreas
Adrenal Glands
Pituitary Gland- found at base of skull. Has anterior and posterior sections
Pituitary & Hypothalamus
Pituitary Gland- both anterior and posterior produce different hormones
Pituitary & Hypothalamus
Pituitary Gland- both anterior and posterior produce different hormones
Pituitary & Hypothalamus
Anterior Pituitary controlled by hypothalamus- has receptors that monitor blood levels of hormones, nutrients, ions.
Pituitary & Hypothalamus
Hypothalamus- its receptors stimulates neurosecretory neurons- synthesize and secrete hormones
Pituitary & Hypothalamus
Hypothalamus- neurosecretory neurons produce releasing hormone (RH) and inhibiting hormone (IH). Stored in axons until needed.
Pituitary & Hypothalamus
Hypothalamus- when needed RH and IH diffuse into capillaries- drain into pituitary by vein.
Pituitary & Hypothalamus
Hypothalamus- vein drains into capillaries in anterior pituitary- portal system- capillaries drain to vein which drains to capillaries.
Pituitary & Hypothalamus
Anterior Pituitary- secretes seven different hormones
Anterior Pituitary
Growth Hormone (GH)- a protein hormone that stimulates cell growth- targets muscles and bones.
Anterior Pituitary-Growth Hormone
Growth Hormone (GH)- undergoes a diurnal (daily) cycle. Highest levels present during sleep or exercise.
Anterior Pituitary-Growth Hormone
Growth Hormone (GH)- release controlled by hypothalamus in a negative feedback loop.
Anterior Pituitary-Growth Hormone
Growth Hormone (GH)- undersecretion during growth phase- dwarfism.
Over secretion during growth phase- giantism.
Anterior Pituitary-Growth Hormone
Growth Hormone (GH)- excess GH production by pituitary after growth phase done causes acromegaly
Anterior Pituitary-Growth Hormone
Thyroid Stimulating Hormone (TSH)- stimulates thyroid gland to release its hormones.
Regulated by daily levels of thyroxine- hormone produced by thyroid.
Anterior Pituitary-TSH
Thyroid Stimulating Hormone (TSH)- travels to thyroid- in neck.
Stimulates production and release of:
1)Thyroxin (T4)2) Triiodothyronine (T3)
Stimulate breakdown of glucose by body cells.
Anterior Pituitary-TSH
Adrenocorticotropic Hormone (ACTH)- Stimulates release of hormones from adrenal cortex.
Stimulates production of glucocorticoids- increase blood glucose levels.
Anterior Pituitary-ACTH
Adrenocorticotropic Hormone (ACTH)- Secretion regulated by:
1)Levels of glucocorticoids in blood (part of negative feedback loop).
2) Stress- acting through nervous system.
Anterior Pituitary-ACTH
Prolactin- Acts on the mammary gland to stimulate milk production in the breasts.
Controlled by a neuroendocrine reflex- involves both nervous and endocrine stimulation
Anterior Pituitary-Protlactin
Posterior PituitaryPosterior Pituitary
Produces ADH and oxytocin
Is a neuroendocrine gland
Hormones made in hypothalamus.
Axons from these neurosecretory cells store hormones in pituitary
Posterior Pituitary- OxytocinOxytocin- 1)Stimulates release
of milk from mammary glands
2) Causes uterine contractions during childbirth
Biology 127- Human Biology Lecture 14Overview of Endocrine System
Pituitary & Hypothalamus
Thyroid Gland
Pancreas
Adrenal Glands
Thyroid Gland- located in the neck. Produces:
1)Thyroxine (T4)2) Triiodothronine (T3)3) Calcitonin
Thyroid Gland
Thyroid Gland- consists of large spherical structures- follicles which contain gel-like substance- thyroglobulin.
Thyroid Gland- T3 & T4
T3 and T4 contain iodine- we take it in through vegetables and iodized salt .
(T4)
Thyroid Gland- T3 & T4
Increase in thyroglobulin that isn’t used in T3 & T4 production leads to enlargement of thyroid = goiter.
Thyroid Gland- T3 & T4
Lack of dietary iodine causes low levels of T3
& T4.
Hypothalmus signals to anterior pituitary to produce more TSH.
TSH causes thyroid to increase thyroglobulin production.
Thyroid Gland