Chapter 45: Animal Hormones Flashcards
Adrenaline
(Epinephrine) a hormone secreted by the adrenal gland and helps the body to adjust to sudden stress; increases strength and rate of the heartbeat and raises the blood pressure; speeds up conversion of glycogen into glucose, which provides energy to the muscles
Hormone
chemical signal secreted into the circulatory system that communicates regulatory messages in the body
2 basic functions of hormones
- responsible for sequential changes of growth and maturation
- agents of response when homeostasis is disrupted
The action of a hormone is entirely dependent on
the target cell
Endocrine gland
gland that secretes hormones directly into the interstitial fluid surrounding the gland and the hormone diffuses into the circulatory system; ductless gland
Exocrine gland
glands that secrete into ducts
Neurosecretory cells
nerve cells that secrete hormones in response to nerve impulses
Neurohormones
hormones produced by neurosecretory cells
Endocrine signaling
secreted molecules diffuse into the blood and affect target cells
Paracrine signaling
secreted molecules diffuse locally and affect target cells (local hormone)
Autocrine signaling
secreted molecules diffuse locally and trigger a response from the cells that secrete them
Synaptic signaling
neurotransmitters diffuse across synapses and trigger responses in target tissues
Neuroendocrine signaling
neurohormones diffuse into the blood and target cells in the body
Local regulators
molecules that act over short distances, reaching target cells solely by diffusion (i.e. paracrine and autocrine signaling)
Neurotransmitters
a molecule released from a synapse that triggers a response (local regulator)
Prostoglandin
a fatty acid that is secreted from a tissue and performs as a local regulator
Human growth hormone (GH) is produced in the
anterior pituitary gland
Human growth hormone (GH) stimulates the growth of
muscle, cartilage, and bone, and causes many cells to speed up protein synthesis, cell division (growth)
Negative feedback after puberty results in
less GH and growth
Cause of gigantism
Overproduction of GH
Cause of dwarfism
Underproduction of GH
Acromegaly
the secretion of excess growth hormone after puberty (when further increase in height is impossible).
Steroid hormone examples
testosterone, estrogen, cortisol
Steroid hormones
lipid-soluble, and can pass directly through the phospholipid bilayer of cell membranes
The receptors for steroid hormones
.lie within or near cell DNA (tend to act slowly)
Nonsteroid hormone examples
epinephrine, insulin, serotonin
Nonsteroid hormones
not lipid-soluble, so they cannot penetrate the cell membrane. Instead, they are picked up by receptors on the cell’s surface. They are mainly composed of amino acids. They are easily transported in the blood. Tend to act quickly and powerfully
binding of the hormone with the receptor initiates a
signal transduction pathway
The actual cell response at the end of the signal transduction pathway may arise as a result of
transcriptional regulation or post translational modification
What regulates the pituitary gland?
Hypothalamus
Pituitary gland
stimulates thyroid and thymus; stimulates growth hormone, water retention, egg/sperm development, milk production, and much more
Adrenal glands
raises blood glucose, affects Na/K levels, produces small amounts of sex hormones, regulates kidney function
Thyroid
regulates metabolic rate and development, lowers calcium levels
Parathyroid
raises blood calcium levels
Thymus
produces T cells for the immune response
Pineal gland
regulates sleep, circadian rhythm, and possibly onset of puberty
Pancreas
monitors blood glucose levels
Gonads
spermatogenesis, oogenesis, secondary sex characteristics
Posterior pituitary releases two non-tropic hormones:
antidiuretic hormone, oxytocin
Non-tropic hormones
hormones that directly stimulate target cells to induce effects
Tropic hormones
hormones that have other endocrine glands as their targets
Oxytocin
involved in generating uterine contractions during childbirth, acts on mammary glands to stimulate milk production
Antidiuretic Hormone (ADH)
regulates and balances the amount of water in your blood
Antagonistic hormones
2 hormones that have opposite effects on a physiological process and thereby exert tight control over the physiological process
glucagon and insulin
control blood glucose
parathyroid hormone and calcitonin
control calcium (Ca2+) levels in the blood
Follicle-stimulating hormone (FSH) and lutenizing hormone (LH)
stimulate the growth and functioning of the ovaries and testes which produce estrogen and testosterone (not produced until puberty)
Thyroid stimulating hormone (TSH)
maintains basal metabolic rate
ACTH
cortisol
Prolactin (PRL)
important in sexually dimorphic traits, stimulates milk production in female mammals.
Melanocyte-stimulating hormone (MSH)
darkens skin
Thyroid hormones regulate metabolic rate through two _____ feedback loops
negative
The hypothalamus secretes ______ that increases secretion of ______ by the anterior pituitary.
TRH; TSH
Diabetes
endocrine disorder in which sufficient uptake of glucose from the blood does not occur.
Two causes of diabetes:
- Beta cells do not produce insulin (Type 1 diabetes; juvenile diabetes)
- Target cells do not respond to insulin because of a dysfunction in the endocrine receptors (Type 2; adult-onset).
Two problems that arise from diabetes:
- blood acidified
2. dehydration
Osmoregulation results from
negative feedback
increased ADH results in ____ urine
More
Alcohol ______ the release of ADH
Inhibits
renin-angiotensin-aldosterone system (RAAS)
part of a complex feedback circuit that functions in homeostasis (blood pressure/fluid balance)
A drop in blood pressure near the glomerulus causes the juxtaglomerular apparatus (JGA)
to release the enzyme renin
Renin triggers the formation of
the peptide angiotensin II
angiotensin II
help to conserve body water and salts to compensate for the increased outflow of both after major wounds or diarrhea
Endorphins are secreted by
The anterior pituitary
