Homeostasis

Question 1

What is homeostasis?

Answer 1

The maintenance of a relatively constant internal environment, despite changes in the external environment.

Question 2

Describe positive and negative feedback loops

Answer 2

Positive feedback: the feedback response INCREASES the original stimulus.
negative feedback: the feedback response DECREASES the original stimulus.

Question 3

What is the major homeostasis organ, and what are its main functions?

Answer 3

Kidney: filters blood and removes waste, controls water balance/pH/ion concentrations in blood

Question 4

What two organs compose the CNS?

Answer 4

Brain, spinal cord.

Question 5

What two types of neurons make up the PNS? What are their functions?

Answer 5

Motor and sensory neurons. Sensory collects information, motor sends commands.

Question 6

Describe the autonomic vs somatic nervous system.

Answer 6

Autonomic: not under conscious control (eg. heart)
somatic: voluntary (eg. muscle movement)

Question 7

Define the sympathetic vs parasympathetic nervous system. What are they classified as (PNS? CNS? Autonomic? Somatic?)

Answer 7

PNS. Autonomic.
Sympathetic: fight or flight response
Parasympathetic : homeostasis after fight or flight

Question 8

What happens in the body when the sympathetic nervous system is activated?

Answer 8

Heart rate and breathing increase. Glucose released from liver for energy.

Question 9

What happens in the body when the parasympathetic nervous system is activated?

Answer 9

Heart rate and breathing decrease (back into homeostatic range).

Question 10

Describe the 3 steps of the reflex arc

Answer 10

1) sensory neuron detects unexpected stimuli
2) message transmitted to interneuron in spinal cord
3) motor neuron activated before message reaches brain

Question 11

Why is there an excitation threshold for action potential? What is this principle called?

Answer 11

All or Nothing principle: All action potential must be above threshold to trigger axon activation. Axon cannot send a mild response, it must be uniform or not at all.

Question 12

What is the resting membrane potential of an axon? How does the membrane maintain this?

Answer 12

-70mV, 3Na+ for every 2K+ that enter the pump to keep a negative charge.

Question 13

During DEpolarization, the membrane potential changes from ______ to _______.

Answer 13

-70 mV, 40 mV

Question 14

How does the axon maintain homeostasis after depolarization changes the membrane potential?

Answer 14

K+ channels open, diffusing K+ out of the neuron.

Question 15

What cause Na+ channels to open during the depolarization phase of an action potential?

Answer 15

Stimulus.

Question 16

Tiny gaps between neurons are called _______, and neurons transmit messages by releasing _________.

Answer 16

Synapses, neurotransmitters.

Question 17

Name the four brain lobes. Give a simple description as to the function of each

Answer 17

Frontal: Complex thinking
Temporal: auditory processing
Parietal: sensory processing
Occipital: visual processing

Question 18

What is the name of the structure connecting the two hemispheres of the brain? What is its main function?

Answer 18

Corpus callosum - allows for signal transmission between lobes.

Question 19

Name the four parts of the limbic system (“emotional brain”). What does each do?

Answer 19

Thalamus: Touch (sensory/motor)
HippocaMpus: Memory
Amygdala: AHH! (Emotion: specifically fear)
Hypothalamus: Homeostasis (thirst, hunger, sleep)

Question 20

Name the three parts of the brain stem. What does each do?

Answer 20

Midbrain: Motor functions (eye/body)
Pons: posture (voluntary muscle movement)
Medulla: Maintains vital body functions (eg. heart rate)

Question 21

What does the cerebellum do? (Remember: cerebellum is the “little brain”)

Answer 21

Balance, movement (eg. Coordination, walking, speech)

Question 22

Name the three types of receptors in the skin. Give a single word description as to what they process.

Answer 22

Nociceptor: PAIN
Mechanoreceptors: TOUCH
Proprioceptors: MOVEMENT

Question 23

Name the three types of hormones. Which ones are lipid soluble?

Answer 23

Amino acid derived hormones, peptide hormones, lipid derived hormones. Lipid: soluble, amino acid: insoluble.

Question 24

Name which 2 hormones are produced by the POSTERIOR pituitary.

Answer 24

Antidiuretic hormone (ADH) and oxytocin.

Question 25

Name the 7 hormones produced by the ANTERIOR pituitary.

Answer 25

ACTH, FSH, GH, PRL, LH, MSH, TSH.

Question 26

There are four hormones released by the anterior pituitary that require a releasing hormone from the hypothalamus. Name them, and their connected RH.

Answer 26

ACTH - CRH
LH - GnRH
FSH - GnRH
TSH - TRH

Question 27

Name the two parts of the adrenal gland. What type of stress does each handle?

Answer 27

Cortex - long term
Medulla - short term

Question 28

What are the three hormone secreted by the adrenal glands? What part releases each?

Answer 28

Cortex - Cortisol
Medulla - adrenaline and norepinephrine.

Question 29

Discuss T3 vs T4, and how levels of thyroxine can affect the body.

Answer 29

T3 is an active hormone, where T4 must be converted to T3 before it can be used. Low thyroxine - hypothyroidism, high levels - hyperthyroidism.

Question 30

What two hormones does the pancreas control? What cells release them? What do they do?

Answer 30

Insulin - alpha cells - stores glucose as glycogen
Glucagon - beta cells - converts glycogen to glucose

Question 31

What is diabetes? What are the types?

Answer 31

Diabetes - pancreas does not release sufficient insulin. Type 1 - juvenile, often from birth. Type 2 - acquired, often from poor diet and little exercise.

Question 32

Discuss what hormone the pineal gland releases. What are its three functions?

Answer 32

Melatonin. Controls sleep/wake, prevents gonadotropin in children, acts as neuroprotective agent.

Question 33

What hormone does the parathyroid gland release? How does it work?

Answer 33

Parathyroid hormone. Acts when calcium levels are too LOW. targets kidneys (release vitamin D) and intestines (triggered by vitamin D) to increase Ca2+ absorption. Also breaks down bone cells if necessary.

Question 34

How is the reproductive system regulated in males?

Answer 34

Hypothalamus releases GnRH. Anterior pituitary releases FSH (sperm) and LH (testosterone). When
levels are too high, inhibin is released and all levels drop.

Question 35

Describe the three stages of the female hormone cycle.

Answer 35

Follicular (menstruation): follicle matures, FSH/LH/estrogen levels low.
Ovulation: follicle releases estrogen, FSH/LH high. Endometrium thickens
Luteal: dead follicle releases low levels of estrogen, FSH/LH low. Endometrium thickens.

Question 36

Discuss taxis vs kinesis. Give an example form the isopod experiment.

Answer 36

Taxis - behaviour biased towards favourable conditions. Kinesis - random behaviour due to stress. Isopods put in the wet/dry experiment moved randomly (kinesis).

Question 37

The proximal tubule of the nephron functions to ________, whereas the distal tubule ________.

Answer 37

Reabsorbs filtrate, regulates water and ion balance

Question 38

The descending loop of Henle passively diffuses water _______ the nephron, creating a __________ gradient. This happens when _________.

Answer 38

1. Out of
2. Hypertonic
3. There is more water than solute inside the cell.