space physiology

Question 1

Q: What happens to the body during long space missions?

Answer 1

A: Astronauts lose bone and muscle, have changes in their heart and blood, metabolism and hormones are affected, and sleep is disturbed.

Question 2

Q: How does gravity affect blood pressure and fluid distribution in the body?

Answer 2

A: Gravity causes blood pressure to vary in different parts of the body: when upright, the head has ~70 mmHg, the heart ~93 mmHg, and the feet ~200 mmHg; when lying down (supine), blood pressure is more uniform at ~93 mmHg.

Question 3

What happens to blood pressure and the body in microgravity, and what syndrome can occur?

Answer 3

A: In space, the normal blood pressure gradient disappears, blood shifts toward the head, and the baroreceptor, nervous, and endocrine systems respond differently. Within minutes, astronauts may experience space motion sickness, including nausea, vomiting, headache, fatigue, and loss of appetite.

Question 4

hy do astronauts experience space motion sickness in microgravity?

Answer 4

A: Changes in gravity alter signals from the vestibular system, creating a mismatch between expected and actual sensory input during movement. This mainly happens because the otolith organs are unloaded in microgravity and usually resolves after about 5 days.

Question 5

What cardiovascular changes occur in the first days of microgravity exposure?

Answer 5

luids shift toward the head and chest, causing swelling in the upper body and shrinkage in the legs, a phenomenon nicknamed “Puffy Head, Chicken Legs.” Forehead circumference can increase by ~7%, while the tibia circumference can decrease by ~15%.

Question 6

How does microgravity affect the heart during spaceflight?

Answer 6

In microgravity, the heart doesn’t need to work as hard to pump blood upward, leading to heart atrophy of about 8–10% after 10 days.

Question 7

: How does the body respond to headward blood shifts in microgravity?

Answer 7

A: Baroreceptors detect the increased blood in the head and activate autonomic and blood volume-regulating reflexes to maintain cardiovascular balance.

Question 8

How does the body compensate for blood redistribution during early spaceflight?

Answer 8

: Initially, heart rate decreases, thirst is reduced, and urine production increases to lower blood volume in the head, neck, and torso. After acclimatization, total blood volume decreases (hematocrit rises), but mean arterial pressure (MAP) and heart rate return to pre-flight levels.

Question 9

How does prolonged microgravity affect the musculoskeletal system?

Answer 9

: It causes loss of bone and muscle mass due to reduced use (disuse atrophy) and changes in blood flow (perfusion).

Question 10

ow does bone loss in space compare to aging on Earth?

Answer 10

During a 6-month stay on the ISS, astronauts lose bone mineral density at a rate similar to someone aging from 50 to 60 years on Earth.

Explanation:

Question 11

: Why do antigravity muscles atrophy in microgravit

Answer 11

In space, humans don’t need to support their bodies against gravity, so antigravity muscles (like those in the legs and back) weaken and shrink due to disuse.

Question 12

Q: Why are spaceflight-related muscle losses important for rehabilitation on Earth?

Answer 12

Muscle loss in microgravity shows which muscles are most prone to atrophy, highlighting the need to focus on these muscle groups during rehabilitation, especially in aging or sedentary individuals

Question 13

add more