Chapter 18 The Endocrine system Flashcards
The nervous and endocrine systems act together to do what?
Coordinate all systems in the body
The nervous system releases what? Opposed to the endocrine system?
Neurotransmitters and hormones
What are the molecules of the nervous systems?
Neurotransmitters released locally in response to nerve impulses
What are the sites of actions for the nervous system?
Close to site of release, at synapse; binds to receptors in postsynaptic membrane
What are the types of target cells for the nervous system?
Muscle fibers, glands cells, other neurons
What is the time to onset of action for the nervous system?
Typically within milliseconds
What is the duration of the nervous system control system?
Generally briefer (milliseconds)
What are the molecules involved in the endocrine system?
Hormones delivered to tissues throughout the body by blood
Where is the site of action for the endocrine system?
Far from site of release; binds to receptors on or in target cells
What are the target cells of the endocrine system?
cells throughout body
What is the time to onset of action for the endocrine system?
Seconds to hours or days
What is the duration of action for the endocrine system?
Generally longer (seconds to days)
What are exocrine glands?
- secrete their products into ducts
- None of these are hormones
Exocrine glands include what?
- sudoriferous (sweat) glands
- Sebaceous (oil) glands
- mucous glands
- Digestive glands
What are endocrine glands ?
- Secrete hormones
- do not have ducts; instead they secrete their hormones directly into the interstitial fluid that surrounds them
What are different types of endocrine glands?
- Pituitary
- Thyroid
- Parathyroid
- Adrenal
- Pineal glands
Just because a organ or tissue excrete hormones does that mean its part of the endocrine system?
Untrue, some organs contain secreting cells
What are secreting cells?
Secreting cells can be found in the
1. hypothalamus
2. thymus
3. pancreas
4. ovaries
5. testes
6. kidneys
7. stomach
8. Liver
9. small intestine
10. heart
11. adipose tissue
12. placenta
Hormones traveling throughout the body will only affect what?
target cells that posses specific protein receptors for the hormone
Receptors are continually doing what?
Being synthesized and broken down
What are two major classifications of hormones?
- Amino- based hormones
- Steroid hormones
Responses to the same hormone may vary depending on the hormone itself and the target cell. What are some of the responses?
- Synthesis of new molecules
- Changing permeability of the cell membrane
- Stimulating transport of a substance into or out of the cell
- Altering the rate of metabolic actions
- Causing contraction of smooth or cardiac muscle
What are lipid soluble hormones?
They bind to receptors within target cells
What are water soluble hormones?
Bind to receptors on the surface of the target cell
How target cell responds to a hormone is based on what?
- The hormones concentration in the blood
- The number of hormone receptors on the target cells
- Influences exerted by other hormones
- Some hormones work more effectively when a second hormone is present to assist them (synergistic effect)
- Some hormones oppose the actions of others (antagonist effect)
Hormones are secreted in what kind of bursts?
Short bursts
Secretions of hormones is regulated by what?
- Signals from the nervous system
- Chemical changes in the blood
- Other hormones
Most hormone regulation is achieved how?
Negative feedback
How many hormones operate via positive feedback?
Few
How are the hypothalamus and pituitary gland connected?
By the infundibulum
The anterior lobe (adenohypophysis) makes up how much weight of what?
75% of the pituitary gland and secretes 7 hormones
The posterior lobe (neurohypophysis) is made of what?
Neural tissue and releases two hormones made by the hypothalamus
The hypothalamus secretes what to control the hormones in the pituitary gland?
Releasing and inhibiting hormones. Which reach the pituitary gland via the hypophyseal portal system
What is HGH?
Human growth hormone is the most plentiful anterior pituitary hormone
How often is HGH released?
Every few hours by somatotrophs
What activates and deactivates HGH?
GHRH (Growth hormone releasing hormone) and GHIH (growth hormone inhibiting hormone)
What does the Anterior pituitary gland secrete?
- Human growth hormone (HGH)
- Thyroid stimulating hormone (TSH)
- Follicle stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
- Adrenocorticotropic hormone (ACTH)
- Melanocyte stimulating hormone (MSH)
What are the principle actions of HGH?
Targets liver. Stimulates liver, muscle, cartilage, bone, and other tissues to synthesize and secrete insulin-like growth factors, which in turn promote growth of body tissues.