The endocrine system Flashcards
What is homeostasis?
the maintenance of a constant internal environment
What mechanisms within the body allow homeostasis to occur?
-Body fluid- acts as an internal environment
-Skin-acts as a barrier
-Cells- are required to stay alive
-Lungs- keep O2 levels constant
-Kidneys-keep nitrogen waste constant (low)
-muscles- keep temperature constant (shivering)
-digestive system- helps keep nutrient levels constant
What does the endocrine system do?
-sends hormones thru the circulatory system to control and coordinate body functions
-works with nervous system
Name some of the functions that are controlled by the endocrine system?
metabolism, growth & development, sexual function & reproduction, heart rate, blood pressure, appetite, body temp
What are the 12 parts of the endocrine system?
Hypothalamus, pineal gland, thyroid gland, thymus gland, heart, adrenal gland, stomach, kidney, pancreas, intestines, ovaries/testes
Describe the role of the hypothalamus in the endocrine system?
- is a cluster of nerve cells that provides the main link between nerve cells and hormones.
-It receives and processes signals from other brain regions and translates them into hormones. These hormones can then travel to pituitary gland
Describe the role of the pituitary gland in the endocrine system?
located below hypothalamus.
-Produces hormones affecting growth and reproduction.
-Also controls function of other endocrine glands
Describe the role of the pineal gland in the endocrine system?
- found in centre of brain-produces melatonin- helps body’s sleep schedule
Describe the role of the Thyroid gland in the endocrine system?
located in front of neck below the larynx. Plays a role in metabolism including maintenance of body weight, rate of energy use, heart rate. Can store hormones
Describe the role of the thymus gland in the endocrine system?
-produces 3 hormones that are involved in development of white blood cells
-produces progenitor cells which mature into T cells. These are then used to destroy cancerous cells.
-Located in upper part of chest
Describe the role of the heart in the endocrine system?
- produces atriopeptin which reduces blood volume and pressure and helpts to regulate fluid balance
Describe the role of the adrenal gland in the endocrine system?
- the outer layer manufactures steroid hormones that regulate metabolism of glucose, sodium and potassium. Also maintains fluid balance.
-The inner layer produces adrenaline
Describe the role of the stomach in the endocrine system?
- makes hormones that stimulate production or release of enzymes that aid digestion
Describe the role of the kidney in the endocrine system?
- secretes erythropoietin which stimulates red blood cell production in bone marrow
Describe the role of the pancreas in the endocrine system?
– contains clusters of cells (islets of Langerhan) which produce hormones insulin and glucagon which lower and raise blood glucose levels when required
Describe the role of the intestines in the endocrine system?
makes hormones that stimulate production/ release of hormones that aid digestion
Describe the role of the ovaries/testes in the endocrine system?
- produce female/male sex hormones, oestrogen and progesterone and testosterone
What features within the body are required to communicate in order to carry out homeostasis?
between organelles, cells, tissues, organs and systems
What are the 2 types of signals used within communication for homeostasis?
-Cell to cell communication of chemical messengers
-Transport of chemical messengers
How does this communication occur?
-involves secretion of molecules (chemical messengers) by cells, into extracellular fluid
-Chemical messengers then travel to target cells
-Target cells contain receptors specific to the chemical messengers
Name the types of chemical messengers?
-Paracrines
-autocrines
-neurotransmitters
-hormones
-cytokines
What is the function of paracrine and how do they work?
-communicate with neighbouring cells in order to produce a response by . They are secreted into extracellular environment and reach their target by diffusion
-Requires a change in concentration gradient for a response to occur
-For a response to occur receiving cell must contain appropriate receptor
What is the function of autocrines/ how do they work?
- the production and secretion of an extracellular mediator by a cell followed by the binding of the mediator to receptors on the same cell
(the secretory cell is the target cell)
-important within survival of pathological conditions eg.cancer
-Is rare
what is the function of neurotransmitters/ how do they work?
-are secreted by neurons from axon terminal across synapse by diffusion to a target cell
-receive and transmit electrochemical signals by neurotransmission
-Neuron is either excitatory or inhibitory depending on type of signal it releases
-signals are sent between pre and postsynaptic cells
What is the function of hormones/ how do they work?
- are secreted from endocrine glands into extracellular fluid where they diffuse into the blood. The blood stream acts as a transport system to reach target cells
What is the function of cytokines/ how do they work?
aid cell to cell communication in immune responses and act on a wide rang of targets-alert lymphocytes
-immune system depends on cytokine signalling to keep body functioning
-when a foreign particles are engulfed a cytokine signal is sent to lymphocytes. The signal is then recognised and lymphocytes are activated- helps maintain homeostasis
What are the different methods of communication between cells?
-gap junctions
-contact-dependant
-local
-long distance
What are the 4 types of hormones?
-peptide and protein hormones
-amino acids
-steroids
-eicosanoids
what can hormones can be classified into?
-water or lipid soluble
Describe how receptor response pathways work?
-Chemical messenger binds to receptor protein
-receptor protein activates intracellular signal molecules
-these molecules then alter target proteins
-this creates a response
what are the key features of negative feedback?
-Helps maintain homeostasis
4 key features:
-System variable (characteristic that needs to be regulated)
-Set point (the ideal concentration of the system variable)
-detector (actual or current value of the system variable which needs to be assessed)
-correctional mechanism (reduce or elimate the difference between the actual value and ideal value)
Describe the role/function of the hormone adrenaline?
-triggers fight/flight response
-causing increased heart and sweat rate, pupil dilation and blood vessel constriction in order to redirect blood towards major muscle groups, including heart and lungs
-Is a protein hormone and binds to complementary receptors outside of target cell to cause a response without entering the cell (is a first messenger)
-causes activation of an enzyme (second messenger) (Adenyl Cyclase)
Describe the role/function of the hormone cortisol
- is a stress hormone
-released from adrenal glands and secretion is controlled by hypothalamus, pituitary gland and adrenal glands
-Response to cortisol release includes: increased blood sugar levels, heightened memory and attention, increased blood pressure, suppression of immune system, decrease serotonin and decreased sensitivity to pain
