Unit 1 Nervous System and Endocrine Sytem Flashcards
What hormones are secreted from the hypothalamus
- hypothalamus = oxytocin, adh
How are the hormones secreted from the hypothalamus involved in homeostasis affecting specific target organs
The hormones secreted form the hypothalamus (oxytocin and ADH) are specialized for the uterus, breast and the kidneys. Oxytocin stimulates the contraction of the uterus and also stimulates the mammary glands, resulting in breast milk. ADH causes the kidneys to remove water from urine that is forming
how are the secretions of the pituitary gland controlled by the hypothalamus through transport of hormones?
The hypothalamus secretes releasing factors which stimulates the secretion of a hormone, or inhibiting factors which slow down the secretion of a hormone. These factors travel through blood vessels to the anterior lobe of the pituitary gland
How can hormones be lipid-soluble and able to cross cell membranes to bind with and activate intracellular receptors?
Steroids are lipid soluble and their mode of action follows the following four steps;
1. Hormone diffuses across the cell membrane (lipid soluble)
- Hormone attaches to the receptor in the cytoplasm/ on the nucleus (hormone-receptor complex formed)
- Hormone-receptor complex enters the nucleus
- Hormone receptor complex activates genes/transcription of mRNA (complex binds to DNA)
how can hormones be water-soluble and able to bind with and activate receptors on cell membranes, and require secondary messengers to affect cell functioning
Protein or amine hormones are water-soluble and follows the following four steps;
- Hormone stays on the outside of the cell membrane (water soluble)
- Hormone attaches to the receptor on the surface of the cell membrane (hormone-receptor complex forms)
- Secondary messenger is activated which diffuses through the cytoplasm
- Activates enzymes in the cytoplasm
whats the difference between endocrine and exocrine glands
Exocrine - secrete into a duct that carries the secretion to the body surface or to one of the body cavities
I.E - sweat glands, mucous glands, salivary glands
Endocrine - secrete hormones into the extracellular fluid that surround the cells that make up the gland
I.E - hypothalamus, pituitary, thyroid, parathyroid, adrenals, pineal
where are each of the endocrine glands located within the body (Hypothalamus, Pineal, Pituitary, Thyroid, Parathyroid, Thymus, Adrenal, Pancreas)
Hypothalamus - brain
Pineal - brain
Pituitary - brain
Thyroid - throat
Parathyroid - throat
Thymus - chest
Adrenal - kidney
pancreas - itself
whats the difference between a paracrine and hormones
Paracrine - relating to or denoting a hormone which has effect only in the vicinity of the gland secreting it.
Hormones - a chemical that is secreted by the endocrine gland that affects the functioning of a cell or organ; often carried in the blood
label and state the function of a neuron (Nucleus, axon, dendrite, cell body, neurilemma, node of ranvier, myelin sheath)
Label the; nucleus, axon, dendrite, cell body, neurilemma, node of Ranvier, myelin sheath
Function - functional units of the nervous system. Highly specialised cells which are perfectly designed for rapid communication of messages in the body
explain the transmission of a nerve impulse (4 Marks) write as paragraph answer in onenote
1) Polarisation
- At a resting, potential the membrane is polarised-inside of the cell and has a net negative charge and the outside of the cell has a net positive charge. A Na/K pump allows these ions to move across the membrane: sodium into the cell and potassium out
2) Depolarization
- the sudden increase in membrane potential
- This occurs if the level of stimulation exceeds 15mV
- Once they are open, more sodium ions move into the cell. this makes the intracellular fluid less negative, increasing the potential difference
- If the stimulus is strong enough to increase the potential to -55mV then voltage-gated sodium channels open
- This produces a movement of sodium ions into the cells
- The size of the response is not related to the strength of the stimulus, this is also known as the all or none response
3) Repolarization
- The sodium channels close, which stops the influx of sodium ions
- At the same time, voltage-gated potassium channels open, increasing the flow of potassium ions out of the cell
- This makes the inside of the membrane more negative than the outside and decreases the membrane potential
- The membrane is repolarized
- The potassium channels remain open longer than what is needed, this results in the membrane potential dropping lower than the resting membrane potential, and the membrane is hyperpolarised
- This process is called hyperpolarization
4) Refractory Period
- Once the sodium channels have opened they quickly become inactivated
- Thus being unresponsive to stimulus
- Therefore, for a brief period after being stimulated, the membrane will not undergo another action potential
What hormones are secreted from the pituitary
- pituitary = fsh, lh, gh, tsh, acth, prl
What hormones are secreted from the thyroid
- thyroid = Thyroxine and T3
What hormones are secreted from the pancreas
- pancreas = Insulin and glucagon
What hormones are secreted from the parathyroid
- parathyroid = PTH
What hormones are secreted from the adrenal gland
- adrenal = Adrenaline and corticosterioids
How are the hormones secreted from the pituitary involved in homeostasis affecting specific target organs
The hormones secreted from the pituitary (FSH, LH, GH, TSH, ACTH & PRL) are specialized for the testes, adrenal cortex, thyroid gland and mammary glands. The have many effects namely;
LH - stimulates sperm production, growth of skin and muscles
TSH - increases metabolic rate
ACTH - promotes normal metabolism and stimulates the reabsorption of sodium ions in the kidney
How are the hormones secreted from the thyroid involved in homeostasis affecting specific target organs
thyroxine and T3 or Triiodothyronin - affects metabolic rate, directly impacting the liver and kidneys
How are the hormones secreted from the parathyroid involved in homeostasis affecting specific target organs
PTH specialized for bones and kidneys and it increases the calcium levels in the blood
How are the hormones secreted from the pancreas involved in homeostasis affecting specific target organs
the pancreas secretes insulin and glucagon.
Insulin regulates the body’s energy supply, whilst glucagon stimulates the breakdown of glycogen and fat
How are the hormones secreted from the adrenal glands involved in homeostasis affecting specific target organs
the adrenal gland secretes cortisol and adrenaline
Cortisol promotes normal metabolism and adrenaline prepares the body for fight or flight responses
Define Homeostasis
The maintenance of a relatively constant internal environment despite fluctuations in the external environment
How do thermoreceptors detect changes in the internal and external environments?
Internal - core temperature
- detected by thermoreceptors within the hypothalamus, detecting the temperature of the blood flowing through the brain
External - changes in temp outside the body
- skin thermoreceptors inform the brain of changes